The impact of prenatal maternal mental health during the COVID-19 pandemic on birth outcomes: two nested case-control studies within the CONCEPTION cohort

Objective Assess the association between prenatal mental health during the COVID-19 pandemic and preterm birth (PTB; delivery < 37 weeks gestation) and low birth weight (LBW; < 2500 g). Methods Pregnant individuals, > 18 years, were recruited in Canada and provided data through a web-based questionnaire. We analyzed data on persons recruited between 06/2020 and 08/2021 who completed questionnaires while pregnant and 2 months post-partum. Data on maternal sociodemographics, comorbidities, medication use, mental health (Edinburgh Postnatal Depression Scale, General Anxiety Disorder-7, stress), pandemic hardship (CONCEPTION—Assessment of Stress from COVID-19), and on gestational age at delivery and birth weight were self-reported. Crude and adjusted odds ratios (aOR) with 95% confidence interval (95%CI) were calculated to quantify the association between PTB/LBW and maternal mental health. Results A total of 1265 and 1233 participants were included in the analyses of PTB and LBW, respectively. No associations were observed between PTB and prenatal mental health (depression [aOR 1.01, 95%CI 0.91–1.11], anxiety [aOR 1.04, 95%CI 0.93–1.17], stress [aOR 0.88, 95%CI 0.71–1.10], or hardship [aOR 1.00, 95%CI 0.96–1.04]) after adjusting for potential confounders. The risk of PTB was increased with non-white ethnicity/race (aOR 3.85, 95%CI 1.35–11.00), consistent with the literature. Similar findings were observed for LBW (depression [aOR 1.03, 95%CI 0.96–1.13], anxiety [aOR 1.05, 95%CI 0.95–1.17], COVID stress [aOR 0.92, 95%CI 0.77–1.09], or overall hardship [aOR 0.97, 95%CI 0.94–1.01]). Conclusion No association was found between prenatal mental health nor hardship during the COVID-19 pandemic and the risk of PTB or LBW. However, it is imperative to continue the follow-up of mothers and their offspring to detect long-term health problems early. Supplementary Information The online version contains supplementary material available at 10.17269/s41997-023-00814-0.


Introduction
was declared a global pandemic by the World Health Organization on March 11, 2020 (WHO, 2022a), leading to the implementation of several public health measures. In Canada, interventions such as closures of non-essential businesses, social distancing, long-term confinement, and self-isolation were implemented on March 13, 2020 (Canadian Public Health Association, 2021). These interventions impacted pregnant individuals' health by reducing in-person clinic/hospital visits and access to other health care services and may have intensified stress levels. Many studies, including the CONCEPTION study , observed that depression and anxiety scores among pregnant persons during the pandemic were greater compared to pre-pandemic scores (Jones et al., 2022;Wdowiak et al., 2021;Zhao et al., 2022). The CONCEPTION study is a longitudinal cohort that was put in place in June 2020 in response to the pandemic and to the immediate need to better understand the impact of the COVID-19 pandemic on the mental and overall health of pregnant persons as well as its impact on their offspring .
External natural events, such as hurricanes, floods, and the COVID-19 pandemic, can contribute to increased populational stress, especially for pregnant persons (Traylor et al., 2020). Exposure to crises can produce short-and long-term health effects on pregnant persons and their offspring (Liu et al., 2016;Marrs et al., 2016). Project Ice Storm, which studied pregnant persons during a crisis leaving a million Quebec/Ontario residents without electricity for up to 45 days, showed that infants' gestational age was shorter than populational averages, and that other birth outcomes were associated with mothers' objective levels of hardship from the disaster and their levels of post-traumatic stress (Dancause et al., 2011). Preterm birth (PTB), defined as birth at < 37 weeks of gestation, is the leading cause of neonatal morbidity and mortality (WHO, 2022b). Worldwide, the prevalence of PTB is approximately 11%, ranging from 5% to 18% (WHO, 2018). Reports found no differences in PTB when comparing rates before and during the pandemic (Badran et al., 2021;Jones et al., 2022;Shah et al., 2021;Vaccaro et al., 2021). However, Yang et al. found decreased spontaneous PTB rates (defined as birth at between 22 and 36 weeks of gestation following spontaneous preterm labour or premature rupture of membranes) but not in induced PTB . In Canada, Shah et al. found no difference in national PTB rates before the pandemic (7.96%) and during the first pandemic year (7.87%, 01/2020-12/2020) .
Low bir th weight (LBW), defined as bir th weight < 2500 g, is associated with increased risk of morbidity and mortality (Blencowe et al., 2019). The global LBW prevalence has decreased over time, ranging from 17.5% in 2000 to 14.6% in 2015 (Blencowe et al., 2019). In Canada, LBW rates were 6.3% in 2013 and 6.5% in 2017 (Statistics Canada, 2018). Studies found no differences in LBW rates prior to and during the pandemic (Badran et al., 2021;Jones et al., 2022;Vaccaro et al., 2021). However, rates of extreme LBW decreased significantly (Badran et al., 2021).
There has been much interest in the association between maternal depression, anxiety, and stress during pregnancy and perinatal outcomes such as PTB and LBW, before and since the COVID-19 pandemic; however, results remain controversial. While severe prenatal maternal depression has been associated with an increased risk of PTB (Dowse et al., 2020;Ghimire et al., 2021;Grote et al., 2010;Wdowiak et al., 2021) and LBW (Dowse et al., 2020;Ghimire et al., 2021;Li et al., 2020), other studies did not observe significant associations with PTB nor LBW (Giesbrecht et al., 2022;Jones et al., 2022;Li et al., 2020). As for maternal anxiety, studies did not find a significant association with PTB (Dowse et al., 2020;Giesbrecht et al., 2022;Khoury et al., 2022;Preis et al., 2021), nor with LBW (Dowse et al., 2020;Giesbrecht et al., 2022;Khoury et al., 2022). On the other hand, maternal stress during pregnancy was associated with increased PTB risk (Preis et al., 2021;Zhao et al., 2022). Of note, studies identifying an association between prenatal maternal mental health and adverse perinatal outcomes had large sample sizes or consisted of a meta-analysis grouping a large number of studies, and most used validated tools to measure depression and anxiety.
Given the limited studies and conflicting results on the association between prenatal mental health and perinatal outcomes during the pandemic, we aimed to evaluate PTB and LBW risks associated with prenatal depression, anxiety, stress, and pandemic hardship. The current study is novel due to its objective measures of hardship endured by pregnant persons in the pandemic.

Study design
We conducted two nested case-control studies within the CONCEPTION cohort.

Setting
The recruitment of pregnant individuals in the CONCEP-TION study started on 26/06/2020 and is ongoing. The methodology has been described extensively and published Gorgui et al., 2022;Pagès et al., 2022). In short, Canadian participants were recruited using (i) press releases and media interviews, (ii) social media (e.g. Facebook, Twitter, Instagram, LinkedIn), (iii) in-person in Montreal, and (iv) posters in OB/GYN clinics where links and/or QR codes were posted and directed participants to the survey page. Upon opening the survey page, they first received information on the project, were assessed for eligibility, and then were asked to give consent to participate before moving onto the survey. Questionnaires were made available in English and French; as such, pregnant individuals in Canada who were > 18 years and able to read/understand English or French were eligible.
We obtained individual consent from participants for the baseline and post-partum (2 months) questionnaires. Both questionnaires were completed through SurveyMonkey®. Data were collected online and then downloaded onto a secure server at the Centre Hospitalier Universitaire Sainte-Justine, Montréal, Québec. Baseline and 2-months post-partum data were linked by J.G. and analyzed blindly by V.T.

Participants
We included singleton pregnancies ending with a livebirth for mothers who completed the baseline and the 2-month post-partum questionnaires between 06/2020 and 08/2021 and between 09/2020 and 04/2022, respectively. We excluded multiple pregnancies, as multiplicity is a risk factor for PTB and LBW. In the first nested case-control analysis, we considered PTB to be cases and those with full-term pregnancies to be controls, while in the second we considered LBW to be cases and those born with a weight > 2500 g to be controls. All eligible pregnancies were analyzed.
Hardship of pregnant individuals: The CASC150 (CON-CEPTION study Assessment of Stress from COVID-19 -150 points) is an instrument measuring overall objective hardship experienced throughout the pandemic, and was developed for the CONCEPTION study by S.K. and G.E. It has a maximum score of 150 points and is scored by summing 3 subscales (Threat50, Loss50, Change50), each having a maximal score of 50. Threat50 assesses the level of threat faced due to COVID-19. Loss50 assesses the level of financial loss due to COVID-19. Change50 assesses the amount of change in the daily life and pregnancy plans experienced due to the COVID-19 crisis. Subscale items and measures are further described in Table S1 and Figure S1.
Infant characteristics and perinatal outcomes: Data included baby's sex (male/female), gestational age at birth, and birth weight, as well as the following perinatal outcomes (yes/no): COVID-19 diagnosis, small fetal size, neonatal intensive care unit (NICU) or pediatric intensive care unit (PICU) admission, bradycardia, jaundice, extra care required at birth (e.g. resuscitation), and congenital malformation.

Data analysis
We first compared the means of scores for maternal depression, anxiety, COVID-19 stress, and hardship according to PTB and LBW status. We then calculated the prevalence of the sociodemographic characteristics, maternal outcomes, medical conditions, and medication use during pregnancy according to PTB or LBW status. Finally, we compared infants' characteristics and perinatal outcomes according to PTB or LBW status. For all descriptive analyses, we calculated standardized mean differences for continuous variables, and chi-square or Fisher's exact test (when samples in categories were < 5) for categorical variables to conduct the comparisons.
Crude and adjusted odds ratios (OR) with 95% confidence interval (CI) were calculated to determine the risk of PTB and LBW associated with prenatal maternal mental health and hardship during the COVID-19 pandemic, using logistic regression models.
In each crude model, we included maternal mental health (depression, anxiety, overall COVID stress) and maternal hardship. For adjusted models, we added maternal age at recruitment, education, maternal ethnicity, annual household income, area of residence, marital status, prepregnancy BMI, care provider (obstetrician/gynaecologist), previous deliveries, maternal lifestyle (coffee intake,   smoking, alcohol consumption, cannabis use, multivitamin use), period of recruitment, maternal outcomes during pregnancy (diabetes, hypertension, preeclampsia, bleeding, or spotting), maternal comorbidities (asthma, diabetes, hypertension, nausea, thyroid disease, anemia, chronic migraines, and others), and medication use (including over-the-counter). We have modelized the association between maternal mental health and both outcomes of interest (PTB and LBW) as well as all variables included in adjusted models in Supplemental Fig. 1.
Given the presence of missing data, multiple imputation was performed on the potential covariates listed above based on a linear regression for continuous variables and logistic regression for categorical variables. Statistical analyses were performed using SAS (version 9.4).

Ethics considerations
The CHU Sainte-Justine's Research Ethics Committee has approved the study (no. MP-21-2021-2973). Table 3 Maternal mental health and resilience during the COVID-19 pandemic SD, standard deviation; SMD, standardized mean difference $ Preterm birth is defined as gestational age at delivery less than 37 weeks & Defined as birth weight at delivery less than 2500 g * Using the Edinburgh postnatal depression scale, continuously / Using the Edinburgh postnatal depression scale cut-off as follows: scale 0 to 8 means no maternal depression, scale 9 to 12 means moderate maternal depression, and scale 13 and more means severe maternal depression + Using the generalized anxiety disorder 7-items scale, continuously − Using the generalized anxiety disorder 7-items scale (GAD-7 cut-off as follows: scale 0 to 9 means no maternal anxiety, scale 10 to 15 means moderate maternal anxiety, and scale 16 and more means severe maternal anxiety) ** Using the overall maternal stress related to COVID-19 measured on a scale from 0 (no stress) to 10 (extreme stress) ++ CASC150 (CONCEPTION study Assessment of Stress from COVID-19 -150 points) is an instrument measuring the overall objective hardship, or objective stress, experienced by the questionnaire respondent. It has a possible maximum score of 150 points −− Threat50 assesses the level of threat that the respondent faced due to COVID-19. It is measured by items indicating if the health or life of the respondent, or their close ones, was threatened due to COVID-19, e.g. if the respondent or people around them suffered from COVID-19 symptoms and their severity, as well as access to food and medical care % Loss50 assesses the level of financial loss due to COVID-19. It is measured by items indicating if the respondent suffered from a loss of income or savings, job security, insurance, or investments, and how this loss of income affected their life (ability to afford childcare or mortgage) // Change50 assesses the amount of change in the daily life and pregnancy plans that the respondent experienced due to the COVID-19 crisis. It is measured by items indicating changes in daily and work routine, social distancing, pregnancy care support, pregnancy class and care practice, and birth plans, due to COVID-19 Bold numbers indicate significant association (p < 0.05) p-values were calculated using chi-square or Fisher test when categories were lower than 5 for categorical variables while standardized mean differences were calculated for continuous variables Maternal stress**, mean (SD) 4.6 (2.0) 4.6 (2.0) 4.4 (1.9) 0.08 4.6 (2.0) 4.6 (2.0) 4.6 (2.1) 0.00 Overall CASC 150 ++ , mean (SD) 28.9 (8.9) 28.8 (8.9) 29.5 (10.1) − 0.07 28.8 (9.0) 28.9 (9.0) 28.2 (8.0) 0.07 Threat50 −− , mean (SD) 3.7 (4.0) 3.7 (4.0) 4.1 (4.5) − 0.10 3.7 (4.1) 3.7 (4.1) 3.9 (4.0) − 0.09 Loss50 % , mean (SD) 6.6 (5.8) 6.6 (5.7) 7.0 (7.5) − 0.08 6.6 (5.8) 6.6 (5.9) 6.2 (4.9) 0.06 Change50 // , mean (SD) 18.6 (4.4) 18.6 (4.4) 18.4 (4.7) 0.04 18.5 (4.4) 18.6 (4.4) 18.1 (4.5) 0.10
Maternal lifestyle during pregnancy, including caffeine, tobacco, alcohol, cannabis, drug, and multivitamin intake, was not different when comparing the term births to PTBs as well as the no LBW compared to LBW (Table 2). Table 3 compares term births and PTBs according to maternal mental health and hardship. There were no differences in the prevalence of maternal depression between the term births and PTBs (7.9, SD 5.2 vs 8.2, SD 5.5, respectively; p = 0.7560) ( Table 3). There were also no differences in mean maternal anxiety between the term births and PTBs (4.2, SD 3.8 vs 4.9, SD 4.4, respectively; p = 0.2597); in the mean maternal stress (4.6, SD 2.0 vs 4.4, SD 1.9, respectively; p = 0.5426); and in mean hardship (CASC150 -28.8, SD 8.9 vs 29.5, SD 10.1, respectively; p = 0.6513) ( Table 3).
When considering maternal outcomes during pregnancy, our findings summarized in Table 4 show that there was significantly more preeclampsia among PTBs (10.8%) than among term births (2.6%) (p = 0.0194), and more reported bleeding/spotting among PTBs (29.7%) than among term births (13.5%) (p = 0.0051). Gestational diabetes was higher among PTBs (22.6%) than among term births (11.1%) (p = 0.0106). Medical conditions and medication use were similar between groups except for chronic migraines: they were more prevalent among PTBs (18.4%) than among term births (4.1%) (p = 0.0012), as was medication use for chronic migraines (13.5% vs 2.7%, respectively; p = 0.0042) ( Table 5). No medical conditions or medication use differed significantly between LBW and no LBW (Table 5). Table 6 presents group comparisons according to infant characteristics. There were significantly more males among PTBs (76.3%) than in the term birth group (51.1%) (p = 0.0022). Overall, the prevalence of adverse perinatal outcomes (e.g. LBW, small fetal size [p = 0.0228], NICU or PICU admission [p < 0.0001], jaundice [p < 0.0001]) was higher among PTBs compared to term births. Indeed, the prevalence of LBW in the PTB group was 44.7% compared to 3.2% in the term birth, which is expected (p < 0.0001). Similarly, the prevalences of all adverse perinatal outcomes were significantly higher among the LBW compared to the no LBW group ( Table 6).

Discussion
In this study, we assessed the associations between the risk of preterm birth and low birth weight and prenatal mental health (e.g. depression, anxiety, and overall pandemic-related stress) and hardship during the COVID-19 pandemic. The prevalences of PTB and LBW among our cohort were 3.0% (n = 38) and 4.5% (n = 55), respectively. After adjustments, we observed no significant associations between prenatal mental health and the risk of PTB and LBW. PTB was significantly associated with known predictors such as non-white ethnicity, having an obstetrician/gynaecologist care provider, preeclampsia, gestational bleeding/spotting, chronic migraines, or any medication use during pregnancy, which is reassuring. Gestational diabetes was associated with increased LBW risk. After adjustments by potential confounders, decreased LBW risk was significantly associated with an annual household income between C$90,001 and $120,000 or > C$150,000 (vs < $60,000), higher pre-pregnancy BMI, and previous live births.
Although information on the impact of prenatal maternal mental health such as depression, anxiety and stress, as well as hardship during the COVID-19 pandemic remains limited, our results are consistent with a number of published studies. In fact, Li et al. (2020) showed no significant association between depression and PTB. No associations between maternal mental health and PTB/ LBW were observed in Wales (United Kingdom), despite a similarly high impact of the pandemic on mental health (Jones et al., 2022). As for anxiety during pregnancy, no significant association with PTB was found (Preis et al., 2021). A number of studies failed to find an association between anxiety and PTB or LBW (Dowse et al., 2020;Giesbrecht et al., 2022;Khoury et al., 2022). Overall, we observed that results are considerably heterogeneous as two studies report significantly increased risk of PTB and LBW associated with maternal stress (Preis et al., 2021;Zhao et al., 2022) and maternal depression (Grote et al., 2010;Li et al., 2020) while others have shown that greater maternal depression is associated with PTB and LBW (Dowse   Wdowiak et al., 2021). These differences in results compared to ours could be explained by the fact that we used different questionnaires to assess maternal mental health. In fact, two studies also using the EPDS, a validated tool to measure depression, did not identify any associations between prenatal maternal depression and the risk of PTB (Li et al., 2020). However, Dowse et al. (2020) found lower gestational age at birth associated with prenatal depression using the EPDS, which could be attributed to their large population compared to ours (n = 53,646). As for maternal anxiety, one study assessing anxiety using GAD-7 did not find a significant association between prenatal anxiety and PTB (Preis et al., 2021). Our data included a new measure of hardship from the COVID-19 pandemic based on relatively objective selfreported items: the CASC150. The total score, and its three subscales (Threat50, Loss50, and Change50), had small-tomoderate associations with greater maternal depression and anxiety, with reductions in life satisfaction since the onset of the pandemic, and with greater perceived stress due to the pandemic. However, neither the total score nor any of the subscales were significant predictors of preterm birth or low birth weight. It is also important to note that the CASC150 has not yet been validated. The failure to find an association between the severity of exposure to the pandemic and birth outcomes is consistent with a recent study that used administrative population data on 147,349 births: birth outcomes (birth weight, LBW, gestational age at birth and PTB) did not differ for pregnancies that were exposed to the 1998 Quebec ice storm compared to pregnancies in the 3 years before and the 3 years after the crisis (Project Ice Storm) (Ahmed et al., 2022). As well, birth outcomes were also unrelated to the estimated duration of power outages for each pregnancy that had been exposed to the storm. If exposure to this severe stressor and the severity of that exposure were not associated with birth outcomes in a large population study, then it is not surprising that no associations were found in the current cohort. However, it is important to note that despite not finding an increased risk of adverse perinatal outcomes in association with maternal mental health, later Project Ice Storm results suggest that child development was impacted by maternal mental health in the long term (Dancause et al., 2011).

Strengths and limitations
Our study is one of the first studies with a longitudinal follow-up to assess maternal and perinatal outcomes during the COVID-19 pandemic. Moreover, our study used a multimethods recruitment strategy which allowed us to recruit effectively across Canada. Our data were collected online, thus accelerating the speed at which the study was performed and allowing us to access real-time data and results, which is essential in the context of an ever-evolving pandemic. In addition, our study is the first to use a fairly objective measure, the CASC150, to assess different aspects of maternal prenatal hardship during the COVID-19 pandemic and the risk of perinatal outcomes. Although the collected data was self-reported, we used validated tools to measure depression (EPDS), anxiety (GAD-7), and stress using a visual analog 10-point scale commonly used in the clinical setting (Lesage et al., 2012) as well as the quality of life indicator used by Statistics Canada (Statistics Canada, 2023).
In our study, we had a lower rate of PTB (3%) compared to the rate in Canada (7.8%), giving us relatively low numbers of PTB (n = 38) and LBW (n = 55), and rendering our study underpowered (4.8% and 25.8%, $ Preterm birth is defined as gestational age at delivery less than 37 weeks & Defined as birth weight at delivery less than 2500 g / Others in high cholesterol, cancer, epilepsy, heart disease, lung disease, ulcer, kidney disease, liver disease, pain, flu, infection, and other diseases Bold numbers indicate significant association (p < 0.05) p-values were calculated using chi-square or Fisher test when categories were lower than 5 respectively -post hoc power calculation). Despite a lengthy questionnaire (≈20 min for the baseline and ≈15 min for the 2-month post-partum), we collected many variables of interest with a high completion rate (85% for both the baseline and the 2-month post-partum). This allowed us to adjust for a number of confounding variables when quantifying the risk of PTB/LBW in association with maternal mental health. This said, we cannot rule out unmeasured confounding, namely history of PTB/LBW which would further bias our results towards the null. Furthermore, our population has a higher annual income than the general Canadian population. In fact, the median household income in 2020 was $104,350 CAD whereas the median salary in our study was between $120,000 and $150,000 (Statistics Canada, 2022). However, access to the study to pregnant individuals was provided across social media groups as well as community clinics, which provide access to individuals with lower socioeconomic status. Given the online recruitment strategy, we cannot rule out the introduction of a selection bias where individuals more concerned with the COVID-19 pandemic would have been included preferentially in the study. However, as we do not have the denominator nor any information on non-participants, this is difficult  to assess. This said, it is possible that given their higher socioeconomic status, higher level of education, and low exposure to substance use, our participants are at a lower risk of PTB/LBW, which would affect the generalizability of our findings to a similar population.

Conclusion
We did not find associations between prenatal depression, anxiety, COVID stress, and pandemic hardship during the COVID-19 pandemic and the risk of PTB and LBW. However, given that the COVID-19 pandemic has had an important effect on increased scores of maternal mental health and the importance of the burden of maternal depression/anxiety/stress, and given the findings from the Project Ice Storm, it is imperative to continue the followup of mothers and their offspring to detect any long-term health problems at an early stage prior to school entry.

Contributions to knowledge
What does this study add to existing knowledge?
• Our study is among the first with a longitudinal followup to assess maternal and perinatal outcomes during the COVID-19 pandemic. -Using the overall maternal stress related to COVID-19 measured on a scale from 0 (no stress) to 10 (extreme stress) + + CASC150 (CONCEPTION study Assessment of Stress from COVID-19 -150 points) is an instrument measuring the overall objective hardship or objective stress experienced by the questionnaire respondent. It has a possible maximum score of 150 points; using 3 subscales: Threat50 assesses the level of threat that the respondent faced due to COVID-19 and is measured by items indicating if the health or life of the respondent/their family was threatened due to COVID-19, e.g. if the respondent or those around them suffered from COVID-19 symptoms and their severity, as well as access to food and medical care. Loss50 assesses the level of financial loss due to COVID-19. It is measured by items indicating if the respondent suffered from a loss of income or savings, job security, insurance, or investments, and how this loss of income affected their life (ability to afford childcare or mortgage). Change50 assesses the amount of change in the daily life and pregnancy plans that the respondent experienced due to the COVID-19 crisis. It is measured by items indicating changes in daily and work routine, social distancing, pregnancy care support, pregnancy class and care practice, and birth plans, due to COVID-19 / Other ethnicity in Aboriginal, Asian, Black, Hispanic, other • Our study uses a multi-method recruitment strategy with data collected online, thus accelerating the speed at which the study was performed and allowing us to access real-time data, which is essential in the context of an ever-evolving pandemic. • Our study introduces an in-depth assessment of the hardship from the COVID-19 pandemic that uses relatively objective items assessing levels of threat, loss, and change. • Though our findings did not demonstrate a statistically significant association, our study gives an opportunity to continue the follow-up of mothers and their offspring in order to detect early any long-term health problems.
What are the key implications for public health interventions, practice, or policy?
• Our study suggests that public health interventions, practice, and policy need to provide adequate prenatal mental health care to mitigate the impact on maternal and perinatal outcomes. • Medical practice and public health interventions should be aware of higher rates of mental health problems among pregnant persons during the COVID-19 pandemic  in order to maximize resources in mental health care and thus provide multiple strategies to reduce the burden on mental health during pregnancy (e.g. medications, physical activity, social support). − Using the overall maternal stress related to COVID-19 measured on a scale from 0 (no stress) to 10 (extreme stress) ++ CASC150 (CONCEPTION study Assessment of Stress from COVID-19 -150 points) is an instrument measuring the overall objective hardship or objective stress experienced by the questionnaire respondent. It has a possible maximum score of 150 points; using 3 subscales: Threat50 assesses the level of threat that the respondent faced due to COVID-19 and is measured by items indicating if the health or life of the respondent/ their family was threatened due to COVID-19, e.g. if the respondent or those around them suffered from COVID-19 symptoms and their severity, as well as access to food and medical care. Loss50 assesses the level of financial loss due to COVID-19. It is measured by items indicating if the respondent suffered from a loss of income or savings, job security, insurance, or investments, and how this loss of income affected their life (ability to afford childcare or mortgage). Change50 assesses the amount of change in the daily life and pregnancy plans that the respondent experienced due to the COVID-19 crisis. It is measured by items indicating changes in daily and work routine, social distancing, pregnancy care support, pregnancy class and care practice, and birth plans, due to COVID-19 / Other ethnicity in Aboriginal, Asian, Black, Hispanic, other

Supplementary Information
The online version contains supplementary material available at https:// doi. org/ 10. 17269/ s41997-023-00814-0. Funding This study is funded by the Faculty of Pharmacy at the Université de Montréal. The funding source had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Data availability
Anonymized individual-level data from the study including data dictionaries, data collection tools, and codes will be made available upon request. Requests for access will be reviewed by a data access committee.
Consent to participate All participants electronically signed an informed consent form prior to completing the survey.

Consent for publication
Subjects consented to having the collected data analyzed and published in peer-reviewed journals.

Conflict of interest
The authors declare no competing interests.
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