The concept of postponement originated in the discovery that very long birth intervals had emerged during the course of fertility transition in Southern Africa (Timæus and Moultrie 2008). It seemed implausible that birth spacing, as it is usually conceptualized, could produce such long intervals. Instead, increasing numbers of women were delaying their next birth for more than five years, suggesting that they were doing something different: postponing. This study adopts a wider perspective and examines both parity progression and birth interval dynamics by birth order. This approach has already proved informative in East Africa (Towriss and Timæus 2018) and becomes essential in analyses that extend beyond Africa to regions where parity-specific limitation is evidently important.
The first striking feature of the results presented here is the enormous variety in the pathways that different countries have taken through fertility transition. In some countries, fertility transition has been driven largely by a rise in the proportion of women who have exactly two children. In other countries, women have begun to restrict their family sizes without showing any sign of adopting small family norms. Instead, the more children a woman has had, the less likely she is to bear another. In many countries, birth intervals have also lengthened because of postponement, spacing, or both forms of birth control. In other countries, intervals have not changed at all. The pattern of fertility change tends to be similar in neighboring countries, but exceptions exist to almost every generalization about regional patterns of fertility decline that one might venture to make.
Our results confirm that fertility transition has been characterized by parity-specific limitation in most of the developing world outside sub-Saharan Africa. Yet, as Casterline and Odden (2016) pointed out, many countries outside Africa have also experienced some postponement of births and lengthening of birth intervals, especially in the second half of their fertility transitions. In contrast, the only evidence of parity-specific limitation in sub-Saharan Africa is in relatively low-fertility countries in Southern Africa, where it has only recently become apparent. Instead, parity progression in Africa has usually dropped the most at high parities, following a similar pattern to that shown for Kenya in Fig. 3. This produces either a steepening linear decline in progression with parity or a convex curve.
Birth intervals have lengthened in much of Africa, but did not do so everywhere. It was never our position that postponement is restricted to Africa. Rather, it is the importance of curtailment of childbearing and the unimportance of differences by parity, rather than the presence of postponement, that most clearly distinguish the first half of the fertility transition in sub-Saharan Africa from fertility transition in most of the rest of the world. Moreover, as we suggested in earlier work, in sub-Saharan Africa, “[B]irth intervals are largely independent of mother’s age and parity. By contrast, data from selected less developed countries in other regions, and from Europe early in its fertility transition, exhibit very different patterns” (Moultrie et al. 2012:253). Postponement and curtailment have emerged as relatively important drivers of fertility transition in sub-Saharan Africa not because postponement is restricted to Africa, but because, so far, parity-specific limitation of family size has been less prevalent in this region than elsewhere.
Although Africa is the region of the world in which postponement of the next birth until more than five years after the previous one is most prevalent, it is also among the world regions that have seen no increase in spacing, defined as a reduction in the proportion of closed birth intervals of less than 30 months. Only in a few countries globally has the entire fertility distribution shifted toward longer intervals over time. In general, little relationship exists between changes in the left and right tails of the fertility distribution. This represents further evidence that spacing and postponement are distinct phenomena, underlain by different sets of reasons for avoiding childbearing.
The results presented here provide few clues as to the institutional or cultural differences that underlie the diverse pathways toward low fertility that countries follow during their demographic transition. They do suggest, however, that women’s fertility intentions are closely interrelated with other aspects of their reproductive lives, including their relationships with men and their partner’s preferences. It is perhaps unsurprising that contraceptive sterilization is common only in countries in which limitation is the predominant form of birth control. However, perhaps the availability and promotion of contraceptive sterilization early in the fertility transition of countries such as India was one factor that encouraged the spread of parity-specific limitation. The relationship is clearly not a necessary one, though, because limitation predominates in those Latin American countries in which sterilization is relatively uncommon, such as Paraguay and Peru, as well as the larger number in which it is very common (UN Population Division 2018).
The acceptability of divorce and remarriage for women around the time fertility transition begins may also be a factor that helps to explain its course. Lengthy postponement of the next birth is common in sub-Saharan Africa, where rates of divorce and remarriage are generally fairly high (Clark and Brauner-Otto 2015), but is not found in India and other South Asian countries, where divorce and remarriage were almost unknown until recently. Within Asia, moreover, postponement is most prevalent in Indonesia, which is one of the few countries in the region in which marital instability has always been common (Dommaraju and Jones 2011).
The adoption of birth control to stop childbearing in the absence of parity-specific limitation at normative family sizes represents a challenge to existing demographic thinking about the process of fertility transition. The following quotations typify the dominant characterization of birth control in the field of demography:
[Birth] control can be said to exist when the behaviour of the couple is bound to the number of children already born and is modified when this number reaches the maximum which the couple does not want to exceed (Henry 1961:145).
Family limitation is deliberate restriction of the number of children born to couples who have reached a certain family size or parity (Pressat 1985:78).
Women who want to stop childbearing will be referred to as “limiters,” and those who have not yet achieved their desired family size as “spacers” (Bongaarts 1992:103).
Spacing behaviour refers to deliberate fertility control that is independent of parity (Okun 1995:86).
Neither Pressat’s (1985) definition of limitation nor Henry’s (1961) argument that limitation is evidence of volitional birth control is in itself problematic. What is problematic, however, is to invert Henry’s argument and assert that limitation is the only form of birth control just because it is impossible to determine whether other forms of birth control are being practiced using the historical data sets that interested Henry and were analyzed later for the European Fertility Project (Coale and Watkins 1986). This is widely recognized today. However, as exemplified by the second pair of quotations, although most demographers accept that limitation is not the only form of birth control, many of them claim, or take as axiomatic, that all birth control that is not limitation must be spacing. This claim is equally problematic.
It is difficult to see how the pattern of decline in parity progression documented here in most of Africa and the Middle East as well as in Afghanistan, Pakistan, and East Timor can result from women targeting a “certain” or “maximum” family size, to use the terms adopted by Pressat and Henry, respectively. Indeed, it is unclear from these data whether women are conceptualizing family size at all. Nevertheless, women in these populations are using birth control to stop childbearing, presumably because they want fewer children than they would have otherwise. Equally, we see no evidence of master schedule spacing—that is, the use of prolonged intervals to limit family size (Anderton and Bean 1985; Bongaarts and Potter 1983). Moreover, it seems perverse to claim that the drops in parity progression in these countries resulted from spacing. Not only does spacing related to the age of the youngest child have little impact on parity progression, but birth intervals have not lengthened at all in about one-third of the countries, including populous ones, such as Ethiopia, Nigeria, and Pakistan.
In some countries, the curtailment of childbearing may have spread because of a rise in proportion of women who are postponing their next birth and become perpetual postponers (Lightbourne 1985)—that is, women who never decide that now is the right time to have another baby. This is not the full story, however, because most of the countries outside Africa that are characterized by parity-independent curtailment—together with some sub-Saharan African countries, such as Ethiopia, Guinea, Nigeria, and Sierra Leone—show no evidence of an increase in postponement.
In a few of the countries, such as Ethiopia, fertility has fallen rather abruptly. In such countries, the pattern of decline in parity progression might result from the initial take-up, at a relatively late date in global terms, of birth control by a population that previously either lacked access to contraceptives or never realized that they could control their fertility. In other words, women started to limit their fertility at whatever family size they had reached at the time when contraception became available, and as younger cohorts build up their families, a more typical pattern of parity-specific limitation may arise. In most of the countries, however, fertility has declined too slowly for this account to be plausible. Instead, an increasing proportion of women may be using birth control, in effect, to retire from childbearing as they become older, more senior, and perhaps more concerned about their health; because their partner has deserted the family or they think that he might; or simply because they feel that they already have enough children to care for and educate (Agadjanian 2005; Bledsoe 2002; Garver 2018; Towriss et al. 2019).
The curtailment of childbearing, by which we mean a pattern of stopping childbearing that is independent of parity, is an important phenomenon that it is hard to reconcile with the traditional characterization of limitation. It seems unlikely, however, that a country could complete its transition to low fertility without curtailment giving way to parity-specific limitation. Low fertility requires most women to have no more than two children. Once women are having families that are this small, choices about whether to start and then how quickly to stop inevitably become issues of central importance to their reproductive lives. Thus, parity-specific limitation has played a role in the fertility decline in all the countries examined here in which total fertility is now less than four children per woman. Moreover, the five mainland sub-Saharan African countries classified as having a mixed pattern of decline in parity progression, together with South Africa, where limitation now predominates, are the six African countries in our study with the lowest fertility. It appears, however, that the argument that “a fertility decline is not very far away when people start conceptualizing their family size, and it cannot take place without such conceptualizing” (van de Walle 1992:502) may reverse the chain of events in at least some parts of the world. Curtailment occurs when people start to reduce the number of children they have without reference to a target family size—they just want fewer. It may be only as successive generations become increasingly confident of their ability to control their fertility that they start worrying about exactly how many children they do want.
The focus of this analysis is on aggregate fertility outcomes. It does not investigate individuals’ reported preferences and intentions beyond documenting that national-level trends in the proportion of women by parity who want no more children are broadly consistent with trends in parity progression. Nevertheless, the large and differential decreases in fertility over time documented in this article can result only from differential increases in volitional birth control rooted in varied changes in women’s fertility preferences and intentions.Footnote 8 Our argument that women in many countries delay or stop childbearing for reasons other than family size limitation or spacing accords with evidence from both quantitative and qualitative research in several parts of Africa that has focused directly on women’s fertility preferences and intentions (Agadjanian 2005; Garver 2018; Hayford and Agadjanian 2017, 2019; Johnson-Hanks 2004; Towriss et al. 2019). Equally, the results presented here add heft to the work of anthropological demographers such as Johnson-Hanks, Bledsoe, and others who have argued that what women do in reality may be far removed from the oversimplified typifications adopted by many demographers and policy analysts (Bledsoe 2002; Johnson-Hanks 2005, 2007; Ware 1976).
The concepts of the curtailment and postponement of childbearing also align with recent literature emphasizing the uncertain, ambivalent, contingent, flexible, and fluid nature of the fertility intentions of women in both contemporary countries and historical Europe (Agadjanian 2005; Fisher 2000; Johnson-Hanks 2004, 2005; Ní Bhrolcháin and Beaujouan 2019; Towriss et al. 2019; Trinitapoli and Yeatman 2018; Yeatman et al. 2013). Limiters who have reached their desired family size might revisit their decision to stop childbearing in the (now rather uncommon) circumstance that one of their children dies. The considerations that lead women to curtail childbearing, however, may be both less clear-cut and more volatile. Similarly, women who are spacing will, in due course, either become pregnant or accomplish that aim. In contrast, women who are postponing childbearing for other reasons may never conclude that their situation has become more conducive to childbearing. Little ambiguity exists about when it is appropriate to limit or to space because decisions to do so are motivated by clearly defined demographic circumstances. The distinction between stopping childbearing and postponing the next birth is fuzzier when the decision has been motivated by factors that are largely unrelated to women’s reproductive histories (Hayford and Agadjanian 2019). Women who are avoiding childbearing for nondemographic reasons may not have decided, or even reflected on, whether they want another child later or not at all. Even if they have formulated their intentions, these may be tentative: the only decision that such women are impelled to make is whether to practice birth control at the current time (Ryder 1973).
One strength of the analysis in this article is that it integrates the regression modelling of period fertility using birth history data with a multistate life table model that calculates the PPRs and durations of birth intervals in a synthetic cohort that experiences the fertility rates of a specific period. Although this method of analysis has been proposed before (Rallu and Toulemon 1994; Retherford et al. 2013), nobody else has applied it previously to a large number of countries undergoing transition. The approach provides a more detailed description of the process of fertility transition across the developing world than has been available hitherto. As well as enabling us to examine progression and birth intervals by birth order, however, multistate modelling yields fully standardized estimates of trends in interval dynamics for all birth orders combined. In contrast, previous research has focused on the changes occurring in a particular birth interval or presented unstandardized measures for all intervals in which the distribution of births by order is determined by the history of fertility change in the population concerned, not by current conditions (e.g., Casterline and Odden 2016).
One limitation of this study is that the available fertility survey data often provide only a partial snapshot of the entire fertility transition in a country. In many Latin American and Asian countries, fertility transition was well underway a decade before they first conducted a fertility survey. Moreover, in most of sub-Saharan Africa, one can only speculate as to how family-building patterns may evolve during the second half of the fertility transition because this is yet to occur. Thus, our identification of the fertility transition in a country as characterized by limitation, curtailment, or postponement might require qualification if information existed on that country’s entire fertility transition. Nevertheless, analyzing the WFS data enables us to document the early stages of enough fertility transitions outside sub-Saharan Africa to make it clear that postponement is not a feature of the initial stages of fertility transition everywhere. Instead, outside sub-Saharan Africa, postponement generally becomes more prevalent as fertility falls to a low level. Parity-independent patterns of stopping, in contrast, seem destined to disappear as the fertility transition proceeds—or, rather, fertility will not fall to a low level until most women use birth control to stop childbearing when they have fewer than three children.
The (literal and conceptual) map that we draw of fertility transition across what was once termed “the developing world” is a complex one. Africa is not unique: a few other countries have experienced “African” transitions. Nevertheless, the overall picture is clear and spatially coherent. The initial stages of fertility transition in sub-Saharan Africa have followed a different track from that taken by almost all the rest of the world. The region has been characterized by the curtailment and (in most countries) postponement of childbearing, without the development of clear-cut preferences for small desired family sizes. The pace of fertility decline in Africa will remain slow until large numbers of African women start limiting their families to only a few children. Gaining a better understanding of the motivations that underlie African women’s family building patterns is essential for the development of appropriate reproductive health care services for Africa. Gaining a better understanding of the consequences of those patterns is vital if we are to understand their implications for future fertility and population growth, not just in sub-Saharan Africa, but globally.
Developing typologies is ultimately an arid exercise if it fails to point the way to explanations. The pathways through fertility transition documented here suggest that in many countries, rather than having a master schedule for their reproductive lives, most women plan their families as they go. If they have enduring quantitative fertility preferences, these are probably numerically imprecise, such as “at least two” or “fewer than my mother.” Wanting to have a(nother) child now, later, or not at all, together with being unsure whether one wants a child later, are an exhaustive and mutually exclusive set of possibilities. Parity-specific family size limitation and birth spacing are not. The terms usefully encapsulate the two main motivations for practicing birth control that relate to women’s reproductive histories. However, characterizing all birth control as either limitation or spacing systematically diverts attention away from nondemographic reasons for intentionally stopping childbearing or postponing having another birth. Changes across the less-developed world during the last half-century in patterns of parity progression by birth order, the length of birth intervals, and interval-duration–specific fertility demonstrate that limitation and spacing are not the only important motivations for adopting birth control. In many countries, large numbers of women practice birth control to stop childbearing for reasons other than limiting their families to some desired size or to postpone having another birth for reasons unrelated to the age of their youngest child.