Changing Lone Parents, Changing Life Courses

The purpose of this book is to approach lone parenthood from a life course perspective. Its chapters address the interdependence of multiple life domains across individuals and between individuals and institutions, as well as the relevance of individual agency and historical context. This introduction describes the phenomenon of lone parenthood across Europe through an account of the changes in prevalence and duration of lone parenthood across cohorts and contexts. Secondly, without any pretention to be an exhaustive review of the literature, it presents an overview of the main topic debated in the literature on the causes and consequences of lone parenthood. Third, it portrays the position of lone parenthood within various forms of social and family policies. It ends with an overview of the chapters included in the volume, highlighting their specific contribution.

phenomenon of lone parenthood is that it is not straightforward to establish even basic descriptive statistics on lone parents across countries and datasets.
Second, the growing likelihood of re-partnering changed lone parenthood into a more temporary phase in the life course. Despite differences in the duration of lone parenthood episodes depending on the gender, the number and age of the children, and the educational and migration background of the lone parent, lone parenthood durations are shorter than in the past. Yet, re-partnering does not always mean the creation of a new residential unit with cohabiting partners; living apart together with a new partner is not rare among separated and divorced parents. In case the nonresident new partner takes up part of the financial and parenting responsibilities, can we still talk about lone parenthood? Boundaries of the definition and complexity of the relationships concerning lone parenthood are just two aspects that exemplify the challenges facing research on lone parenthood in the XXI century (see the Chap. 2 by Letablier and Wall for a systematic discussion of definitions).
This introduction gives first an overview of the recent trends in lone parenthood across Europe filling a gap in the scientific empirical literature on lone parenthood, which is rarely comparative and rather dated by now (with the exception of the recent report on lone parents in the UK by Berrington 2014). Second, it gives an overview on the literature on lone parents in relation to other life course domains like employment, health, poverty, and migration. We also touch on parenting and children's outcomes. We conclude with a brief discussion on the universalistic and targeted welfare approaches to meet those lone parents in need of support. We hold that the current volume represents a first step to relaunch research on lone parenthood in the XXI century through a life course perspective. This is much needed updated knowledge and reflection on a changing phenomenon given that an ever-greater number of children spend at least part of their childhoods in one-parent households, their social background and needs are more heterogeneous than in the past, their relation with parents and grandparents are increasingly complex, and last but not least, the institutional context in which their family lives impacts children's life chances significantly.
With the spread of union disruptions, an ever-greater number of children grow up during at least a part of their childhood in a one-parent household because many of them live in increasingly complex families, because their social background and their needs are more and more heterogeneous, and because the institutional context in which their parents live has important consequences for how lone parents and their children fare in comparison with other families.

Prevalence of Lone Parents in Europe
The phenomenon of lone parents as a social group that deserves special attention by policies arose during the nineties when one-parent households became statistically visible (Bradshaw et al. 2000;Kennedy et al. 1996). Several studies have made calculations of the prevalence of one-parent households throughout Europe and other OECD countries. Unfortunately, most of these rates differ a lot according to the source being used. Most international comparative surveys have been used to look at lone parenthood: ECHP (Chambaz 2001), PISA (Chapple 2009), LIS (OECD 2015), and EU-SILC (Iacovou and Skew 2010). Some rates are calculated among the percentage of families with children (OECD 2011), often because the survey on which it is based contains only families with children (Chapple 2009). Also, definitions are often not exactly the same. Sometimes children are counted until the age of 15 (Chapple 2009), 18 (Iacovou and Skew 2010), or 25 years (Chambaz 2001). Also, the inclusion of so-called 'included' lone-parent families (those sharing an accommodation with another household) might lead to considerable differences in rates (Chambaz 2001).
All this diversity in previous studies makes it difficult to make comparisons with previous results. In this introduction, we use the Harmonized Histories 1 with comparable data on fertility and marital histories from 18. In our analyses, we define lone parents as single living adults in the age range of 15-55 with children aged 18 or younger present in the household. 2 Lone parents take on an increasing share of all households throughout the past five decades (Table 1.1). In all countries, we see an increase in the prevalence of lone parenthood even though the cross-country variation is huge. As was shown with other data (Iacovou and Skew 2010;OECD 2011), the USA, the UK, and Russia end up in the top. Sweden has been found to be a high-prevalence country as well but shows only an average rate in our analyses. The low-prevalence countries are southern European countries and Poland, Romania, and Georgia.
In Table 1.2, we look in more detail at the first spell of lone parenthood in the life course. The mean age at the first episode of lone parenthood circles around thirty in all countries. Lower mean ages are found in the USA but not in the UK. Given the high proportion of teen pregnancies, we would have expected this mean age to be lower in the UK. Probably this is due to the omission of 'included' lone parents, as most of the teen mothers continue living with their parents and remain unobserved in these analyses. Also, the length of lone parenthood differs considerably across countries, with Switzerland, Georgia, Lithuania, and Russia showing the longest spells of lone parenthood. This may mean that chances of re-partnering for lone parents depend on the local context or an indication that divorce happens at different stages in the life courses (when divorces occur at later ages, children are rightcensored quicker out of the household). A more detailed analysis of lone parenthood durations is shown in Table 1.3, where we consider changes in durations across cohorts by country. Re-partnering chances for lone parents seem to have increased over birth cohorts. Most countries experience a jump in re-partnering chances in  1951-1960 cohort or the 1961-1970 cohort. In older cohorts, the average length of lone parenthood approximates 8-10 years, whereas the younger cohorts clearly move towards 4 or even 2 years on average. This is a sign that lone parenthood status is changing in nature. We will elaborate on that in the next paragraph. Table 1.2 also shows some variation according to educational level. There is, however, no clear pattern to be discerned across countries. In some countries, most highly educated clearly have better chances of leaving lone parenthood status, while in other countries those with an intermediary level of education are better off. According to gender, men have much shorter spells of lone parenthood compared to women. Probably, this is a sign of differences in custody arrangements (being more favourable for men in terms of chances on the partner market) or a reflection of the general higher chances of men on the partner market.
The 2011 OECD study revealed that children in lone-parent families are becoming older, while the size of the lone-parent families is shrinking (OECD 2011). We find few country differences in the size of lone-parent families (Table 1.4). Only the UK and the USA have larger lone-parent families, more or less attributable to educational level. The most highly educated lone-parent families are larger than the least educated ones. There is little or no difference in size between a mother-headed and a father-headed lone-parent family.  15-55, period 1960-2010)

Life Course Trajectories of Lone Parents
In the previous paragraph, we demonstrated that the average length of the first spell of lone parenthood differs across countries. In this paragraph, we further concentrate on lone parenthood in a life course perspective. Seldom, the dynamic nature of lone parenthood has been shown in cross-country overviews. The prevalence of lone parents in comparative studies usually suggests an instantaneous view on the share of lone parents in one single country. Life course analyses reveal that over time, lone parenthood is a transitionary state, with adults being active on the partner market and successfully engaging in new relationships.
In Table 1.5, we provide more insight in the household composition of lone parents, 1 year before entering lone parenthood and 1 year after exiting this state. Not surprisingly, most lone parents were either married or cohabiting before a relational breakup that left them alone with the children. Countries showing higher rates of cohabitation like Norway and Sweden also generate more lone parents from that state. Only Spain seems to be a peculiar exception to this rule: The vast majority of lone parents were cohabiting before lone parenthood, while Spain is known for very high marriage rates. A possible explanation of this outlier might be some kind of stigma that is associated with cohabitation preventing lone parents from being 'included' in the parental home after a breakup. Chambaz (2001) showed that Spain has higher rates of 'included' lone parenthood. Because these lone parents are masked in our analyses, we might find a statistical artefact here when stigma indeed prevents adult children returning home after a breakup. The first and third columns in Table 1.5 show the prevalence of married or cohabiting partners without children turning into lone parents 1 year later. These refer to a relational breakup of pregnant women which may give an indication of unwanted pregnancies. These rates are typically higher among cohabiters than in marriages. The last column in the table shows adults who become parents outside a relationship. The data are unclear about the exact singleness status 1 year before lone parenthood. We do not observe marriage or cohabitation in the data, but they might represent deliberately single parents or living-apart-together (LAT) relationships. We do not possess any information to make the distinction between these two.  1921-1930 1931-1940 1941-1950 1951-1960 1961-1970 1971-1980 1981-1990  Leaving the lone parenthood status goes in two pathways. First, the lone parent re-partners by entering marriage or cohabitation. Again, Sweden, Norway, and the USA show much higher rates of cohabitation than marriage. Overall, in most countries, new relationships are more often cohabitations than marriages. Only in Hungary do we see a very high remarriage rate among lone parents. The second route out of lone parenthood occurs when the parent no longer has children in the household. This could indicate a change in the custody arrangement, but it might as well be an empty nest. Again, the data do not allow us to make this distinction. As Table 1.4 has shown fairly high average ages of lone parents, we assume that most lone parents exit their lone parenthood status when the last child becomes independent.
The last analysis (Table 1.6) further elaborates on lone parents' chances to re-partner. Using Kaplan-Meier estimates, we describe the patterns and tempo of re-partnering among lone parents. This analysis shows that re-partnering occurs at a much slower speed in Eastern European countries like Bulgaria, Georgia, Lithuania, and Russia. Other Eastern European countries like Estonia and Romania show particularly quick re-partnering routes. Also, Germany and the UK have partner markets that make it easier for lone parents to re-enter a new cohabitation or marriage. For a majority of lone parents throughout Europe, living alone with children is a state that takes at most 5 years. In almost all countries included in our analyses, we see that half of the population of lone parents re-partners within 5 years, and in a majority of countries, almost three-quarters of lone parents exit the status within 10 years. Of course, the prevalence of empty nests in this 5-to 10-year period increases dramatically, as not only lone parents but also their children age (and partner) during this period.

Challenging Life Domains for Lone Parents: Poverty, Work, and Health
Even though the lone parenthood state is often a transitory state in the life course, it interferes severely in many life domains. Many studies have pictured the short-and long-term consequences of becoming a lone parent. In this section, we give an 1 Changing Lone Parents, Changing Life Courses overview of the field by focusing on lone parents' work trajectories, health outcomes, poverty risks, and the implication of migration for lone parenthood. This overview only targets the lone parents themselves. In the next paragraph, we expand our overview to the children of lone parents because being a lone parent automatically involves dependent children.

Work Trajectories
Work, care, and income are a triangle of intertwined influences and dependencies that are difficult to see completely independent from each other. In this and the next two paragraphs, we will summarize the main findings of this complex equilibrium. We will do so from an individual perspective since the institutional influence on work and care is discussed in paragraph 7. As lone parents are predominantly women, the research on employment patterns of lone parents focuses on female labour participation. Men, whether single, married, or lone parent, show consistently successful and stable employment histories and are therefore left out of most studies. In general, there is an increase in the female labour market participation across OECD countries. In most countries, the employment rate surpasses 60% (OECD 2011). Scandinavian countries are well above this average, while the UK is characterized by a rather low employment rate among lone parents (especially lone mothers) (Millar and Rowlingson 2001). The UK shows a double outlier position, as the country has not only lower rates compared to other countries but also shows an employment gap within the country compared to employment rates of married women (Gregg and Harkness 2003). A caveat on these rates, however, is that even though single mothers in many countries have higher employment rates, they do more part-time work than mothers in partnership or childless single women (Ruggeri and Bird 2014).
The presence of lone mothers on the labour market has been shown to be highly selective. First, lone mothers are more likely to be less educated leading to trajectories in lower-skilled and worse-paid jobs (Stewart 2009;Zagel 2014;Zhan and Pandey 2004). Being stuck in the lower-skilled and lower-paid jobs also implies an increase in what Bauman (2002) calls the hidden costs of employment: increased financial costs for childcare, higher transportation costs, and a decrease in available hours for direct household needs. Second, the household composition itself plays a role. The higher the number of children and the younger these children are, the less likely a lone mother will be to work. The effect is found consistently in the literature and is plausible. The more children there are and the younger the children, the more the time budget of the lone mother is constrained (Drobnic 2000;Hancioglu and Hartmann 2012). Both the costs for young children not going to kindergarten or school and the costs for an increasing number of children in the household are a significant burden to the labour supply of lone mothers. Third, life course researchers also point to the moment in the life course where lone parenthood occurs. Both finding or keeping one's job is more difficult when experiencing lone motherhood at a young age than when experiencing lone motherhood at middle age (Chevalier et al. 2003). Fourth, social benefits like single-parent allowances also turn out to have a negative effect on the labour supply of lone mothers. As the financial burden after the breakup is softened, women are less encouraged to increase their labour supply (van Damme et al. 2009).
Following the work of Hakim (2000) on preferences of women for work or care, several authors have looked into the issue of whether it is the preferences or attitudes of women that keep them off the labour market. These authors call attention to the cultural dimension of labour supply instead of focusing only on the structural and institutional factors (Gingerbread 2012). One prominent response to Hakim's criticized typology is worked out by Bell et al. (2005). They position labour market decision on two axes: (1) a work orientation axis and (2) a parental care orientation axis. This double approach shows that women can have both high aspirations on the labour market and high aspirations to care, which was impossible in Hakim's typology. They also construct the typology with a dynamic perspective, as aspirations can change over the life course. A more recent study by Boeckmann et al. (2014) confirms the importance of looking at cultural norms regarding maternal employment in addition to individual and system characteristics.

Poverty
Probably one of the firmest associations of lone parenthood in both policy circles and in academia is that with poverty. There is a huge amount of evidence that the state of lone parenthood is associated with poverty. One of the most comprehensive overviews by the OECD (2011) shows poverty rates among lone parents ranging from less than 10% to over 40%. The lowest poverty rates are found in the Scandinavian countries (Sweden and Denmark), while the highest numbers come from the US, Australia, and Canada. In Europe, high poverty figures are also found in Spain, Germany, Estonia, the UK, and Ireland. The main foci in the research on how to tackle these extraordinary poverty figures among lone parents are either on income taxes (Brady and Burroway 2010;Heuveline et al. 2003) or on transfers and family policies (Maldonado and Nieuwenhuis 2015;Van Lancker et al. 2015). From both perspectives, results suggest that universal transfers are more effective for lone parents than measures targeting them as a specific group (Brady and Burroway 2010;Chzhen and Bradshaw 2012;Maldonado and Nieuwenhuis 2015).
Many factors that explain this increase poverty risk have already been documented. On the one hand, factors associated with work potential (see section "Parenting") like low-paid jobs and part-time work contribute to an increase in poverty risk. On the other, family-related factors like large families or families with young children and low human capital also contribute to the risk of poverty for lone parents. Also, inadequate payment of child support by the ex-spouse deprives lone parents of necessary sources of income (Zhan and Pandey 2004). It shows the close interrelation between labour market participation and poverty across countries (Maldonado and Nieuwenhuis 2015;Ritakallio and Bradshaw 2006). Again, life course researchers have pointed to the dynamic nature of this phenomenon. Placing the poverty risk in a life course framework showed the accumulated disadvantage of more vulnerable social groups (less educated, precariously employed, in bad health) and the reinforcing character of episodes of lone parenthood therein (Tsakloglou and Papadopoulos 2002;Vandecasteele 2010Vandecasteele , 2011.

Health Trajectories
The association between poverty or social inequality and (bad) health conditions has received firm empirical evidence (e.g., Mackenbach et al. 2008). As the association between lone parenthood and poverty is quite firm, it comes as no surprise that health issues are also correlated with the state of lone parenthood. Evidence has been found for both worse general health conditions (Whitehead et al. 2000) and increases in mental health issues (Crosier et al. 2007). The central question in this respect is whether the impoverished background of many lone parents is the main reason for the bad health or the status of lone parent as such is responsible for the worse health conditions (Benzeval 1998). The first link is documented elaborately in the literature on health inequalities and will not be discussed here. Intrinsic reasons for worse health among lone parents are predominantly related to the stress that accompanies the status of lone parent. The combination of work and care for children in a single headed household is much harder, leading to more stress and health issues. In addition, a lack of social support from the (decreased) social network adds to the strain of being lone parent (Cairney et al. 2003).
More recently, much attention went to the buffering influence of welfare states in the association between lone parenthood and health on the one hand and the changes in such association over time on the other hand (and its relatedness to economic crises). In three Swedish studies, the temporal shift in health outcomes was put under scrutiny (Burstrom et al. 1999;Fritzell and Burstrom 2006;Fritzell et al. 2007). The studies showed the emergence of lone parents as a vulnerable social group during the nineties and the first decade of the new century. Economic strain is increasingly associated with the worse health conditions of lone parents, even though the Swedish welfare state intervenes substantially. In follow-up comparisons between Sweden, Britain, and Italy, economic conditions turned out to be less important as a main factor to explain bad health, but the synergy between lone motherhood and non-employment turned out to be a highly important mediation factor (Burstrom et al. 2010;Fritzell et al. 2012;Whitehead et al. 2000). The comparative study revealed influences of both policy regimes and a country's culture and tradition. Lone mothers in this respect are considered a 'litmus' test of the interface between family policy systems and health (Burstrom et al. 2010). When extending the number of countries, regional health inequalities appear throughout Europe with CEE countries reporting the worse health conditions for all (lone and cohabiting) mothers, while the Anglo-Saxon regime negatively influenced self-rated health of lone mothers and Bismarckian welfare regimes showing a more devastating effect on mental health of lone mothers ( Van de Velde et al. 2014).

Migration and Lone Parenthood
While there is growing interest in the union behaviour of immigrants (Huschek et al. 2010;Kalter and Schroedter 2010;de Valk and Milewski 2011), little is known about their family structure. In particular, differences between immigrants and natives in the prevalence and incidence of lone parenthood and the consequences of such differences for immigrants' life courses are little investigated.
This state of the art is possibly due to the fact that lone parents are mostly lone mothers, while migration research for a long time had concentrated on the economic migration of men. Until recently, most migrants were men, migrating alone in the first place and followed by wives and children a few years later when this was possible. The number of lone mothers migrating alone with children was limited. In addition, most migrant groups were in relatively stable unions so that, also after migration, in most Western countries, the likelihood of entering lone motherhood for immigrant women was lower than for the native populations (Landale et al. 2011;Milewski and Kulu 2014). Yet, with the feminisation of migration flows (Lutz 2007) and with the diffusion of divorce and its acceptance in most sending countries as well as among the second generations in the receiving countries (Andersson et al. 2015), studies on immigrant lone parents are much needed. In addition, migrants have specific pathways to lone parenthood. One of them may be related to an unfavourable marriage market for immigrants; the high unemployment rates of immigrants often translate into fewer opportunities for marriage for immigrant women. Under such circumstances, the literature on lone mothers in minority groups suggests that women may then put motherhood before marriage (Edin and Kefalas 2005;Lichter et al. 1992;McLaughlin et al. 1992). Another specific pathway to lone parenthood for immigrants may be related to the process of migration itself: an immigrant woman may enter the destination country while her male partner stays behind, either because he is entrapped in civil wars or because of time-lasting employment obligations in the country of origin (Landale et al. 2011).
Using PISA data in a cross-country comparative perspective, a recent study establishes that the risk of being a lone mother in the country of immigration is positively and significantly correlated with the prevalence of lone mothers in the country of origin but not with that of the country of destination (Dronkers and Kalmijn 2015). The same study concludes that immigrant mothers with a partner who were born in the destination country (in a mixed marriage) and who speak the destination language at home with the children are at higher risk of being lone mothers when their children are 15. Interestingly, the same study finds that while for all children of lone parents, immigrants and natives, there is a disadvantage in school performance with respect to children living in two-parent families, such a gap is smaller in the immigrant population. They interpret all their findings as a proof that immi-grant lone mothers are positively selected for being more integrated in the culture of the destination country with respect to partnered immigrant mothers. Those kinds of studies call for future research on the interrelation between lone parenthood and migration.
Yet, research in this field faces challenges related to data availability, in particular when they want to explore pathways in and out of lone parenthood and follow the trajectories of migrant lone parents. The relatively small number of migrants in general panel samples, and their higher probability of dropping out of panel designs, often hinder the examination of the migrant population of lone parents by generation or ethnic group, or by important characteristics like the presence or absence of institutional and social support.

Parenting
Two contemporary trends in the employment and family domains combine to impact mothers' care practices and parenting. One trend is the spread of parental employment, especially of mothers' employment, and the corresponding secular decrease in the percentage of nonworking parents (Fox et al. 2013). The second trend is the parallel trend in the banalisation of separation and divorces and the increasing share of children who live, at least for some time, in one-parent households, generally with the mother. As a consequence, lone mothers often have the sole or most of the responsibility for caring and providing for their children, managing the household, and organising childcare during employment activities. How do lone mothers organize care, especially when they work? And how does lone motherhood affect parenting practices?
Lone mothers enjoy less social support than mothers in couples (Mac Lanahan et al. 1981;Amato 1993). The greater care burden among single mothers may also leave less room for the more enjoyable and rewarding aspects of parenting, especially for non-working mothers. Past evidence has suggested that lone mothers' parenting is characterized by less parental engagement (Carlson and Berger 2013) despite the fact that lone mothers spend more solo time with their children than mothers in couple (Kalil et al. 2014). Nevertheless, the effects of lone motherhood on parenting are all but straightforward. Research has highlighted both positive and negative effects of lone motherhood on mother-child interaction. The time squeeze due to mothers' employment and care responsibilities may create feelings of inadequacy and have spillover effects on the relationship and interactions with children (Blair-Loy 2003;Nomaguchi et al. 2005).
At the same time, the consciousness of being able to provide economically for the children and the engagement in activities and relations other than care may have positive spillover effects on the quality of time spent with children (Garey 1999;Latshaw and Hale 2016;Yetis-Bayraktar et al. 2013). In addition, time with children alone can produce very positive feedback on mothers' well-being, providing mothers with a source of meaning related to their role as provider and carer as indispensable (Edin and Kefalas 2005;Villalobos 2014).
A recent study whose aim was to assess the role of partnership status and employment on mothers' well-being and emotions related to parenting, found that, lone mothers report in general less happiness and more sadness, stress, and fatigue in parenting than mothers living in couple. Yet, employment seems to be an important mediator, since employed lone mothers seem to be happier and less stressed than those who are not employed (Meier et al. 2016). Lone mothers seem to suffer from worse subjective health particularly when they have limited labour market prospects, perhaps relying on low-skill part-time employment contracts (Struffolino et al. 2016) or occasional jobs (Campbell et al. 2016). Qualitative research aiming at understanding how lone parents prioritize their responsibilities shows that when employment time conflicts with sole responsibility for parenting (because of lack of childcare), caring obligations take priority. As a consequence of the double responsibility, this burden may result in exhaustion with multiple roles and harsher parenting (Breitkreuz et al. 2010) as well as the inability to supervise children. Parents express concerns about the safety of their children when older children are required to look after younger siblings (Hildebrandt and Kelber 2005). A second consequence in such cases is that the ability to work or maintain employment may be impaired, entailing a vicious circle of disadvantages (Good Gingrich 2010).

Child Outcomes
Studies have repeatedly shown a clear empirical association between growing up in a one-parent household and poor child outcomes, especially when such a family structure results in a drop in income and in parental involvement (McLanahan and Sandefur 1994). Children of divorce and living in one-parent households have consistently worse educational outcomes and lower levels of well-being compared to children of intact families (Amato and Keith 1991;Amato 2005). In addition, in a life course perspective, there is evidence for the intergenerational transmission of lone parenthood. Children growing up with lone parents have higher chances of experiencing lone parenthood themselves, whether because of transmission of teenage pregnancies or of separation and divorce (MacLanahan and Sandefur 1994).
The observed association between family structure and negative child outcomes has been explained with both causation and selection mechanisms (Amato and James 2010; Thomson and McLanahan 2012). The most common causal explanations given to explain research findings are the higher economic hardship of onehousehold families, the poorer parenting quality of lone mothers, and the more frequent exposure to stress of their children (Amato 2005). Such explanations have in common that it is the fact of living in a one-parent household that produces negative consequences for children in most countries.
A different set of explanations look at parents' characteristics, like their genetic, social, cultural, and economic resources, and posit that these may be the important determinants of children outcomes. Resource-poor individuals may be selected to become lone parents either by not entering couples or being more likely to see their couple break down. For instance, a longitudinal study on single mothers who enter parenthood without a partner showed they suffered from socio-economic disadvantages before becoming mothers (Baranowska-Rataj et al. 2013). In such cases, it would not be the condition of lone parenthood to affect their children, but rather the selection into lone motherhood of disadvantaged women. Parents may transmit disadvantageous traits to their children either through genetic inheritance or inadequate interaction with their children. In this case, the observed association of growing up in a one-parent family and negative child outcomes may be a spurious effect of some inherited parental characteristic influencing both. Selection mechanisms are difficult to test and to rule out without longitudinal or quasi-experiment data and may be involved to a certain extent.
Empirical evidence has so far consistently supported causal explanations indicating that it is growing up with one parent that has put children at higher risk of having cognitive, emotional, and social problems (Amato 2005). Yet, it is an open question for future research whether, as a consequence of the diffusion of one-parent households across social strata and the average shorter duration of lone parenthood episodes (which means shorter exposures to stress, poor parenting and economic hardships for children), the relative influence of causal mechanisms will weaken and selection will become more important (see Chap. 15 by Hannan in this volume).

Welfare States and the Support for Lone Parents
Two strategies are available to policy makers when it comes to tackling lone parenthood negative outcomes. First, universalistic types of intervention do not target lone-parent households as such, but address those negative outcomes within the general population (e.g., any universal health care system providing services on the basis of a universal right to receive health care). Second, targeted types of intervention tackle lone parent households as their only public (e.g., advances of maintenance payments) in order to target those negative outcomes that are typically associated with lone parenthood. It should be clear, though, that no welfare state entirely fits one of the two models as, in fact, policies are diverse and different strategies can be adopted within different policy fields (e.g., the UK blends a universal health care system and a "New Deal for Lone Parents", including a set of measures intended to increase lone parents' labour market attachment).
Two main goals underpin policy interventions specifically addressing loneparent households (Table 1.7). Preventing and alleviating poverty for the household, and especially for children, is one of the most recurrent goals. This is done to buffer the negative consequences of living in a single-earner household. The most popular policy tools in this case are tax breaks, family allowances supplements, advances of maintenance payments, childcare benefits, social assistance or housing supplements, and income supplements for lone parents (OECD 2011). Allowing parents to stay in the labour market (see Brady in this volume) is also an exigency that policies attempt to respond to in order to buffer the consequences of the double-burden dilemma. 3 Some of these policies primarily intend to support lone parents with their caring commitments by either subsidizing alternative care (i.e. childcare benefits) or providing paid leave so they can take time to undertake the care themselves (i.e. parental leaves). Other policies seek to help parents stay in the labour market through workfare programmes attached to income support payments. Such policies are generally referred to as active labour market policies (ALMP) (Martin and 3 Lone parents are simultaneously single earners and single carers in the household.  Millar 2003), as it is clear the same programme can serve more than one policy aim (e.g., income support to alleviate poverty and improve labour market attachment). Researchers started to investigate the impact of social policies on lone parents' outcomes, arriving at two important conclusions: First, assessing the overall policy framework and the interaction among policies is important to have a better understanding of the outcomes for lone parents (e.g., Misra et al. 2007); second, the role of universalistic interventions in buffering lone parenthood negative outcomes is not to be underestimated, as shown by some studies (Brady and Burroway 2010;OECD 2011).

Overview of the Book
The purpose of this book is to approach lone parenthood from a life course perspective. The contributed chapters address critical aspects of the life course perspective like the interdependence of multiple life domains, linked lives, and the relevance of individual agency in context. They are organized in order to cover major issues at stake in the study of lone parenthood and lone parents' life courses. The first part of the book, including four chapters, is devoted to the definition of the phenomenon on lone parenthood, whether it is related to the ways in which lone parents are identified in the statistical and administrative records, the public debate, or the comparison between such external definitions and the more subjective self-image of lone parents themselves.
In the opening Chap. 2, Letablier and Wall broadly discuss lone parenthood in the context of family diversity characterizing Europe since the 1960s. With a focus on France, they compare the prevalence and characteristics of lone parents through time and critically examine the criteria used to define lone parent families, based on residence or on economic responsibility for children. Central to this analysis is the discussion of the extent to which such criteria relate to concepts of parenthood and parental responsibilities and challenge current social policies schemes addressing poverty and deprivation risks incurred by children living in one-parent households.
Salter, in Chap. 3, touches on the important aspect of the public image on lone parents in the UK, a country with the highest percentage of lone mothers in Europe. She critically addresses the stereotypical social representation of lone mothers as economically dependent on public support and as poor-quality parents, through an analysis of newspaper articles that appeared during two specific years, 20 years apart, and belonging to opposite political perspectives. The results point out at a homogeneous discourse both across time and through the political spectrum.
When targeting lone parenthood, often studies are focussed on adult mothers and fathers. In Chap. 4, Portier-Le Cocq reports on a qualitative study among young teenage mothers in the UK. The chapter looks at their financial, emotional, and social ways of coping with their early motherhood. The study shows how young girls often do not get pregnant by choice but by force and have little or no access to emergency contraception. A wide range of reasons also prevent them from having an abortion, and many of them show regrets afterwards for having the baby. On the other hand, the teenage mothers showed a great urge to prove they could manage, including efforts to combine work and care. Poverty and dropping-out of school, however, often hamper these intentions.
Addressing the issue of definitions and concepts related to a changing phenomenon, Bernardi and Larenza, in Chap. 5, use a set of open-ended interviews with lone parents in Switzerland to capture the transition to lone parenthood as defined by those parents who experienced it. They question to what extent women and men living alone and having the sole responsibility for their children identify themselves as lone parents and as a consequence of what change in their life. They conclude that the transition to lone parenthood is an often non-linear and ambivalent one and give suggestions on how to improve current measurements of the timing and occurrence of lone parenthood.
The second part of the volume includes three chapters devoted to the analysis of the diversity of lone parents in term of their socio-demographic characteristics and their family trajectories and relationships.
Informal social support is the topic of Chap. 6, in which Keim employs a mixedmethods design to describe lone mothers' social network structure and composition as well as the ways in which such contacts contribute to mothers' well-being. Data consist of an original set of problem-centred interviews and structured network data of 26 unemployed lone mothers living in eastern Germany, a particularly vulnerable group of lone parents. The resulting network typologies account for the size, the composition, and the role of network members in providing support. Results highlight a large heterogeneity in the social integration of lone mothers and provide a solid description of the ways in which networks represent a resource for them.
Do lone mothers suffer from a double disadvantage on the labour market when they have a migrant background? Studies looking at the interaction between family structure and migration are still rare. In Chap. 7, Milewski, Struffolino, and Bernardi analyse the Swiss Labour Force survey to examine the employment situation of immigrant women, whether lone mothers or mothers in couple, and contrast them with natives. Thanks to the large dataset, they can define various employment statuses by differentiating between full-time, long and short part-time employment, and non-employment as well as migrant generation and origin. Results show the double risk of international migrant lone mothers to be either unemployed or work full-time more often than native lone mothers. In the Swiss context, where child care services are insufficient and the number of mothers who work full-time is relatively small, family work reconciliation may represent an additional disadvantage and a source of stress for migrant lone mothers, who often lack informal support from faraway family members.
In the third part of the volume, three chapters address two major research themes in studies of lone parenthood from a life course and social inequality perspective: Lone parents' relative and absolute poverty in different institutional contexts and how the transition to lone parenthood affects income trajectories.
Is a husband really the main protection from poverty for a (lone) mother? This question is answered in Chap. 8. Hübgen answers the question by taking a European perspective using pooled SILC data. Three hypotheses are tested: (1) gender inequalities in the labour market and the welfare system increase the poverty risk; (2) gender inequalities in working hours and wages increase the poverty risk, despite being employed; and (3) the less progressive work-family policies are in a country, the greater the young children increase lone mothers' poverty. The results show that gender inequality in a country is indeed responsible for part of the cross-country variation in lone mothers' poverty risk. It also turns out that the structure of the labour market is partly responsible for the extent to which full-time employment may have a poverty-reducing effect among lone mothers.
Mortelmans and Defever in Chap. 9 analyse the economic trajectories of those who enter lone parenthood after divorce, taking advantage of the Belgian register data for Flanders. They compare employment and family trajectories after marital breakups, with special attention to income losses and gains thereafter. Focusing on the differences between men and women, and between lone parents and other family structures, they conclude for women, and not for men, re-partnering represents a way to improve their financial status. Yet, all in all, the 'financial consequences of divorce are still highly gendered', with women who head lone-parent households suffering from longer-lasting income drops significantly more than men.
The British Household Panel Survey is an excellent data source to observe trends in families over a long period. In Chap. 10, Harkness uses the BHPS to get a closer understanding of the economic consequences of women making the transition to lone mothers. As other chapters in this book report for other European countries, UK lone mothers are faring badly economically and in terms of labour market participation. The chapter shows how these circumstances are to a large extent influenced by the occurrence of the lone motherhood in the life course. It is predominantly young and less educated women who suffer financially from lone motherhood. In addition, the low labour market participation of these women is not related to benefit receipt. Low labour market participation is associated with a selection into lone motherhood rather than a deliberate choice in order to receive state support.
The concluding four chapters (part IV of the volume) discuss the important interdependence on the one hand between lone parenthood and employment and, on the other hand, lone parenthood and health.
One of the main ways that many countries have sought to alleviate the poverty that many lone mothers face is through increasing their labour market attachment. In theory, earning a reasonable wage through paid employment should reduce lone mothers' poverty, but in practice, this is not always the case due to high childcare costs and the withdrawal of income support payments once these individuals start earning an income. In Chap. 11, Brady draws on data from a three-year qualitative longitudinal study to illustrate how access to informal childcare in the context of a mixed (formal and informal) childcare package can be a crucial factor in enabling lone mothers to combine paid work and care in Australia. The study shows that the combination of formal and informal childcare results in mothers being able to enter the labour force with greater ease, lessens the pressure they face in balancing paid work and care commitments, and helps them to adapt to their children's changing childcare needs. This assistance supports these lone mothers to have stronger labour force trajectories over time. This chapter illustrates that the childcare needs of lone mothers are very dynamic and much more complex than often assumed in quantitative studies. Furthermore, it shows that the inflexibility of formal childcare arrangements is far more problematic for lone mothers than previously assumed.
Struffolino and Mortelmans, in Chap. 12, start with the fact that the poverty risk for one-parent families is significantly higher compared to households composed of couples with children and compared to the general population. The authors analyse data from the Crossroads Bank of Social Security (CBSS Datawarehouse) and study the Flemish lone mothers' patterns of labour market participation. Given a context of generous unemployment and that social assistance benefits are available, their aim is to establish what individual and household characteristics of lone parents are associated with which kind of employment trajectories. It appears that an early selection into lone motherhood is associated with lower employment opportunities. Additionally, the number of children underage living in the household negatively influences the labour market attachment of lone mothers and raises their likelihood of being unemployed or on social benefits.
Selection mechanisms are at the core of the investigation of the association of subjective health and lone parenthood in Chap. 13 by Dinescu, Haney-Claus 2 , Turkheimer, and Emery. Adopting a twin research approach, and the large Swedish Twin Register dataset, they determine the extent to which the observed relation between lone parenthood and depression is the result of genetic and shared environmental confounds. The authors show that despite selection being responsible for part of the association between lone motherhood and depression, it does not rule out the presence of causal mechanisms related to lone parenthood itself.
A longitudinal setup characterizes a complementary study by Kuhn in Chap. 14, which looks at changes in satisfaction with health and well-being of lone mothers during the transition into lone motherhood. The results unequivocally show that, besides separation, the transition into and the duration of lone motherhood have significant negative effects on health satisfaction and well-being. Yet, there are important buffering factors such as being in a LAT relationship and the number of underage children. Socioeconomic circumstances, such as income change and employment status, play an important moderation and result in heterogeneity in well-being trajectories during the transition into lone motherhood.
Selection is important to understand social phenomena. The possible neglect of selection bias is also one of the drawbacks of many studies on the consequences of divorces. In Chap. 15, Hannan presents empirical evidence for the association between lone parenthood and children's well-being. Using the Growing Up in Ireland child cohort study, the results show that despite the huge selection differences into family types, the structure of the family does have an influence on children's well-being. More specifically, math scores and school attendance remain lower among children from never-married one-parent families. Nevertheless, taking out the selection effects drastically reduced the differences between families, indicating that it is not the lone parenthood status as such that predominantly determines child outcomes.
Laura Bernardi is Professor of Life Course Demography and Sociology at the Faculty of Social and Political Sciences at the University of Lausanne, Switzerland, and Deputy Director of the Swiss National Center for Competence in Research LIVES. Her major research areas are fertility, family demography, migration and life course. She has published in major demograpic and sociological journals on topics like fertility intentions and behaviour, social network influences on family development, intergenerational transmission of fertility and family formation, lone parenthood and health, migration and family formation. She is also co-editing the Springer series on Life Course and Social Policies. Open Access This chapter is licensed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.
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