Changes in Racial and Ethnic Inequities in Pregnancy-Associated Death in the United States During the COVID-19 Pandemic.

Objectives. To examine changes in cause-specific pregnancy-associated deaths during the COVID-19 pandemic by race and ethnicity and assess changes in racial and ethnic inequities in pregnancy-associated deaths. Methods. We used US vital statistics mortality data from 2018 to 2021 to identify pregnancy-associated deaths among females aged 15 to 44 years. We calculated crude pregnancy-associated death rates (deaths per 100 000 live births) by year, cause, and race/ethnicity, percent change in death rate, and the inequity (difference) in rate for each racial or ethnic group compared with non-Hispanic White people. Results. The pregnancy-associated death rate for obstetric, drug-related, homicide, and other causes of death increased during 2020, and obstetric deaths continued to increase in 2021. Overall estimates mask 2021 increases in drug-related deaths among Hispanic, non-Hispanic American Indian and Alaska Native (AI/AN), and non-Hispanic Asian people; increases in homicide among most racial and ethnic groups; and increases in suicide among Hispanic, non-Hispanic AI/AN, and non-Hispanic Asian people. Conclusions. We found disproportionate increases in pregnancy-associated deaths from nonobstetric causes among minoritized racial and ethnic groups during the COVID-19 pandemic. (Am J Public Health. Published online ahead of print May 16, 2024:e1-e10. https://doi.org/10.2105/AJPH.2024.307651).

Did the Affordable Care Act Promote Racial Equity in Pregnancy-Related Health? A Scoping Review.

In the United States, there are profound and persistent racial and ethnic disparities in pregnancy-related health, emphasizing the need to promote racial health equity through public policy. There is evidence that the Affordable Care Act (ACA) increased health insurance coverage, access to health care, and health care utilization, and may have affected some pregnancy-related health outcomes (eg, preterm delivery). It is unclear, however, whether these impacts on pregnancy-related outcomes were equitably distributed across race and ethnicity. Thus, the objective of this study was to fill that gap by summarizing the peer-reviewed evidence regarding the impact of the ACA on racial and ethnic disparities in pregnancy-related health outcomes. The authors conducted a scoping review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR), using broad search terms to identify relevant peer-reviewed literature in PubMed, Web of Science, and EconLit. The authors identified and reviewed n = 21 studies and found that the current literature suggests that the ACA and its components were differentially associated with contraception-related and fertility-related outcomes by race/ethnicity. Literature regarding pregnancy health, birth outcomes, and postpartum health, however, was sparse and mixed, making it difficult to draw conclusions regarding the impact on racial/ethnic disparities in these outcomes. To inform future health policy that reduces racial disparities, additional work is needed to clarify the impacts of contemporary health policy, like the ACA, on racial disparities in pregnancy health, birth outcomes, and postpartum health.

The Association Between Adverse Childhood Experiences and Preterm Delivery: A Latent Class Approach.

Background: Racial and socioeconomic status (SES) disparities in preterm delivery (PTD) have existed in the United States for decades. Disproportionate maternal exposures to adverse childhood experiences (ACEs) may increase the risk for adverse birth outcomes. Moreover, racial and SES disparities exist in the prevalence of ACEs, underscoring the need for research that examines whether ACEs contribute to racial and SES disparities in PTD. Methods: We examined the relationship between ACEs and PTD in a longitudinal sample of N = 3,884 women from the National Longitudinal Study of Adolescent to Adult Health (1994-2018). We applied latent class analysis to (1) identify subgroups of women characterized by patterns of ACE occurrence; (2) estimate the association between latent class membership (LCM) and PTD, and (3) examine whether race and SES influence LCM or the association between LCM and PTD. Results: Two latent classes were identified, with women in the high ACEs class characterized by a higher probability of emotional abuse, physical abuse, sexual abuse, and foster care placement compared with the low ACEs class, but neither class was associated with PTD. Race and SES did not predict LCM. Conclusions: Our findings suggest that ACEs may not impact PTD risk in previously hypothesized ways. Future research should assess the impact of ACEs on the probability of having live birth pregnancies as well as the role of potential protective factors in mitigating the impact of ACEs on PTD.

The prevalence of food insecurity amongst refugees and asylum seekers during, and prior to, their early resettlement period in Australia: A cross-sectional analysis of the 'Building a New Life in Australia' data.

With over 100 million humanitarian migrants globally, there is increasing pressure on high-income countries to offer resettlement opportunities. Humanitarian migrants face many challenges during pre-settlement and resettlement. One challenge is food insecurity (FI). The Building a New Life in Australia (BNLA) longitudinal cohort study gathered data from migrating units, that is, a group of humanitarian migrants included on the same visa application (n = 1599). Data were gathered in five annual waves (2013-2018). Data included food security status in four pre-settlement situations and during resettlement. The results of this secondary analysis of BNLA Wave One indicate that FI was highest in refugee camps (71%), followed by bridging visas (30%), community detention (17%), immigration detention (11%), and during early resettlement (9%). During early resettlement, respondents who were male, those from Afghanistan or Iran, and those living in a single person household reported the highest prevalence of FI. An association was found between having spent time on a bridging visa and FI during early resettlement (p < 0.01). This study's results are an important step in understanding the scale of FI and which sub-groups are most vulnerable, so the resources and policies of high-income countries can better meet food security needs during resettlement.

Food and nutrition information requirements of Australian primary school parents.

OBJECTIVE: To explore what Australian primary school parents want to learn about food and nutrition to improve their children's eating behaviours, as well as the associations between parents' personal and demographic characteristics and their views regarding their food and nutrition knowledge needs. DESIGN: An online nationwide cross-sectional survey was conducted in 2021 using a mixed-methods approach. Logistic regression analysis was utilised to examine the relationship between parents' demographics, personal values and their views. Content analysis was performed using Leximancer. SETTING: Australia. PARTICIPANTS: Seven hundred and eighty-seven parents. RESULTS: Fifty-one per cent wanted to learn more about food and nutrition to improve their children's healthy eating habits, and 77% of those preferred schools to provide that information. Online/printed newsletters and YouTube were the most preferred methods for receiving food and nutrition related information. Higher universalism-concern value (concern for the welfare of those in the larger society and world) scores were positively associated parents' preference for schools to provide food and nutrition-related information. Parents with non-English-speaking backgrounds and younger parents were more likely to want to learn about food and nutrition. Parents wanted to learn more about encouraging healthy eating, ideas for the lunchbox, food labels and age-specific portion sizes and recommendations. CONCLUSIONS: Findings can inform public health educators and assist them in designing future food and nutrition education programmes and resources targeting primary school parents.

Parents face several barriers in providing a healthy school lunch for their primary school children: A survey of Victorian (Australian) parents.

ISSUE ADDRESSED: This paper aims to explore Victoria parents' perceptions of their current practices and barriers in providing school lunches for their primary school children. METHODS: Respondents were asked via an online survey about their lunch provision practices, perceptions of the healthiness of school lunches, and barriers to providing healthy school lunches. Data were analysed using different statistical techniques: Chi-square test, Spearman correlation analysis, Mann-Whitney U test, and Kruskal-Wallis test. RESULTS: In total, 359 respondents completed the survey. Most respondents (84%) reported their child takes a home-packed lunch to school every day. Most respondents provided fruits (94%), vegetables (57%), and sandwiches (54%) every day for school lunches, whilst other core food items such as milk, meats, and legumes were provided less frequently. A substantial proportion of respondents provided some discretionary food items frequently (e.g., the proportion of respondents providing selected discretionary food items daily or 3-4 times/week: salty crackers-50%, sweet cookies/biscuits-40%, chips-20%). Respondents strongly agreed or agreed with several barriers; examples include not packing certain foods due to food spoilage concerns (50%) (school-related), the allocated time at their child's school is not enough to eat and enjoy school lunch (48%) (school-related), need more meal ideas (61%) (parent-related), healthy foods take more time to prepare (51%) (parent-related), and children request easy-to-eat food for school lunches (50%) (child-related). Core food score (an indicator of frequency of preparing/packing core food) was negatively correlated with parent-related and child-related barrier scores, whilst discretionary food score (an indicator of frequency of preparing/packing discretionary food) was positively correlated with these barrier scores. CONCLUSIONS: Overall, home-packed lunches remain the main option in primary schools in Victoria, and parents face several challenges in providing healthy lunches for their primary school children. SO WHAT?: The findings suggest the need for strategies from school leaders, education authorities, and policymakers to improve the quality of lunch content and address the barriers faced by parents.

Australian adults cooked more and tried new recipes during COVID-19 restrictions and lockdowns.

The lockdowns and restrictions due to COVID-19 caused changes in both food accessibility and availability for people around the globe resulting in changes in food habits and behaviours. To enable a better public health response to the next pandemic, lessons must be learnt from this most recent emergency. This study aimed to examine self-reported changes in food habits and behaviours, of Australian adults during COVID-19 restrictions in 2020. A cross-sectional, convenience, Australia-wide survey, with open-ended and closed-ended questions was conducted online. Respondents were asked to report their demographic characteristics, positive food habit development, worst food-related experiences, changes in food habits and behaviours and cooking and food preparation practices during the COVID-19 restriction period. Adult Australian residents, recruited through social media advertising of the survey. Respondents (n = 764) were mostly female (86%), over 55 years of age (57%, mean age (SD) 53.4 (18.1) years), and half (51%) were not in paid employment. Nearly two-thirds (63%) developed positive food habits, including trying new recipes (54%), eating less take-away (53%) and cooking from scratch (46%) during the COVID-19 restrictions. Furthermore, respondents reported including family members in food preparation and eating together as a family. Negative experiences included being unable to buy certain foods (due to lack of stock and store limits), cooking at home, and being unable to access some food outlets. Australians experienced both positive and negative food experiences during the COVID-19 pandemic and associated lockdown periods, with most experiencing positive changes such as cooking at home from scratch and trying new recipes and relying on less take-away. Females and those who experienced a change in employment status were more likely to develop positive new food habits.

Food literacy and diet quality in young vegans, lacto-ovo vegetarians, pescatarians, flexitarians and omnivores.

OBJECTIVE: To investigate whether food literacy competencies and diet quality vary between 16-to-24-year-olds vegans, lacto-ovo vegetarians, pescatarians, flexitarians and omnivores and to assess whether food literacy is associated with diet quality. DESIGN: Cross-sectional study. Food literacy (general nutrition knowledge, critical nutrition literacy and food skills) and diet quality were measured using an electronic questionnaire. SETTING: Southern Norway, September 2021 - March 2022. PARTICIPANTS: Healthy 16-24-year-olds (n 165). RESULTS: Overall, the mean general nutrition knowledge score was moderate (48·0 out of 67·0); the lowest mean score was found in omnivores and the highest in flexitarians (45·6 v. 51·5) (P = 0·034). The mean score of critical nutrition literacy was also moderate (3·7 out of 5·0); vegans showed higher scores compared to other dietary practices (P = 0·018). No difference was observed in food skills between the different dietary practices. The overall median diet quality score was 46·0 out of 80·0, lowest in omnivores and highest in vegans (42·0 v. 56·0) (P =< 0·001). In multivariate regression analyses, general nutrition knowledge, food skills and vegan dietary practice were significantly associated with higher diet quality. CONCLUSIONS: We found moderate levels of food literacy across all dietary practices. The food literacy competencies, general nutrition knowledge and food skills were associated with higher diet quality in our sample. Omnivores showed both the lowest general nutrition knowledge level and lowest diet quality scores. In contrast, both flexitarians and vegans scored highest on general nutrition knowledge and diet quality scores, despite being one of the less restrictive and one of the strictest plant-based dietary practices, respectively.

Parental support for free school lunches in Australian primary schools: associated factors and perceived barriers.

OBJECTIVE: (1) To explore the feasibility of such programmes in Australia, this study examined parents' views on free school lunch provision. (2) To examine the associations between parents' demographic and personal characteristics and their support for free universal school lunches. DESIGN: An online cross-sectional survey of parents. SETTING: Australia, April 2021. PARTICIPANTS: Seven hundred and eighty-seven parents took the survey. They had a mean age of 40. The respondents were predominantly female (95 %) and had a university degree (72 %). RESULTS: Fifty-three percentage of the respondents agreed that all students should have access to healthy and well-balanced, free school lunches. Parents were concerned about healthiness, catering, allergies and cost of school-provided school lunches. Ethnic background, universalism values and education levels were significantly associated with support for free school lunch provision. Non-native English-speaking parents were almost three times more likely to support free universal lunches in primary schools than their native English-speaking counterparts. Parents with higher universalism-concern values were more likely to endorse free lunches in primary school. However, the level of education was negatively associated with parents' support for free school lunches. CONCLUSIONS: The survey results highlight the complexity of parental views on free school lunch provision. Parents' concerns regarding lunches should be considered in developing school lunch programmes that meet the needs and preferences of diverse communities. These findings can be used to guide future primary school lunch provision initiatives.

Associations of a current Australian model of dietetic care for women diagnosed with gestational diabetes and maternal and neonatal health outcomes.

BACKGROUND: Gestational diabetes mellitus (GDM) is a significant public health burden in Australia. Subsequent strain on healthcare systems is widespread and current models of care may not be adequate to provide optimal healthcare delivery. This study aimed to assess a current model of dietetic care with maternal and neonatal outcomes. METHODS: Hospital medical record data from The Women's Hospital, Melbourne, for women with GDM (n = 1,185) (July 2105-May 2017) was retrospectively analysed. Adjusted linear and logistic regression were used to analyse associations between the number of dietitian consultations and maternal and neonatal health outcomes. RESULTS: Half of all women (50%) received two consultations with a dietitian. 19% of women received three or more consultations and of these women, almost twice as many were managed by medical nutrition therapy (MNT) and pharmacotherapy (66%) compared with MNT alone (34%). Higher odds of any maternal complication among women receiving 3 + consultations compared to those receiving zero (OR = 2.33 [95% CI: 1.23, 4.41], p = 0.009), one (OR = 1.80 [95% CI: 1.09, 2.98], p = 0.02), or two (OR = 1.65 [95% CI: 1.04, 2.60], p = 0.03) consultations were observed. Lower odds of infant admission to the Neonatal Intensive Care Unit (NICU) were observed among women receiving one (OR = 0.38 [95% CI: 0.18, 0.78], p = 0.008), two (OR = 0.37 [95% CI: 15 0.19, 0.71], p = 0.003), or three + consultations (OR = 0.43 [95% CI: 0.21, 0.88], p = 0.02), compared to no consultations. CONCLUSION: The optimal schedule of dietitian consultations for women with GDM in Australia remains largely unclear. Alternate delivery of education for women with GDM such as telehealth and utilisation of digital platforms may assist relieving pressures on the healthcare system and ensure optimal care for women during pregnancy.

Association of the 2021 Child Tax Credit Advance Payments With Low Birth Weight in the US.

Importance: Infants and pregnant people in the US fare worse on almost all health measures compared with those in peer nations. Families in the US are more likely to live in poverty and have a less generous social safety net, which has generated debate over the contribution of economic conditions to this disparity. Objective: To assess the association between temporary increases in income during pregnancy through the 2021 expanded Child Tax Credit (CTC) and birth outcomes. Design, Setting, and Participants: This cross-sectional study applied a comparison-population, interrupted time series design to data from US birth certificates (January 1, 2014, through December 31, 2021) to test whether the log odds of low birth weight (LBW) among monthly cohorts of births exposed to the CTC would coincide with a decreased incidence of LBW. All singleton live births to US residents aged 15 to 49 years with available data were included. Exposure: Monthly birth cohorts exposed to the CTC were defined as those born to parous people during the CTC advance payment period from July through December 2021. Main Outcomes and Measures: The main outcome was the natural logarithm of the odds of LBW (<2500 g) among monthly birth cohorts. Results: Among included births (n = 28 866 466), 61.2% were to parous people, the majority were to people aged 20 to 39 years (91.7%), and 6.5% were born LBW. The odds of LBW increased above expected values in 5 of the 6 months of the CTC payments (range of increases, 3.3%-5.4% across the 5 months). The outlier-adjusted odds of LBW increased, on average, by 4.2% (95% CI, 2.7%-5.7%) among the monthly birth cohorts exposed to the CTC. Conclusions and Relevance: This study found that the odds of LBW among birth cohorts exposed to the CTC increased above expected values in 5 of the 6 months of the CTC advance payments. Additional research is needed to evaluate rival explanations for this increase in LBW among births exposed to the CTC payments.

A novel indicator of selection in utero.

Background and objectives: Selection in utero predicts that population stressors raise the standard for how quickly fetuses must grow to avoid spontaneous abortion. Tests of this prediction must use indirect indicators of fetal loss in birth cohorts because vital statistics systems typically register fetal deaths at the 20th week of gestation or later, well after most have occurred. We argue that tests of selection in utero would make greater progress if researchers adopted an indicator of selection against slow-growing fetuses that followed from theory, allowed sex-specific tests and used readily available data. We propose such an indicator and assess its validity as a dependent variable by comparing its values among monthly birth cohorts before, and during, the first 10 months of the COVID-19 pandemic in Sweden. Methodology: We apply Box-Jenkins methods to 50 pre-pandemic birth cohorts (i.e., December 2016 through January 2020) and use the resulting transfer functions to predict counterfactual values in our suggested indicator for selection for ten subsequent birth cohorts beginning in February 2020. We then plot all 60 residual values as well as their 95% detection interval. If birth cohorts in gestation at the onset of the pandemic lost more slow-growing fetuses than expected from history, more than one of the last 10 (i.e. pandemic-exposed) residuals would fall below the detection interval. Results: Four of the last 10 residuals of our indicator for males and for females fell below the 95% detection interval. Conclusions and implications: Consistent with selection in utero, Swedish birth cohorts in gestation at the outset of the COVID-19 pandemic included fewer than expected infants who grew slowly in utero.

The impact of place-based contextual social and environmental determinants on preterm birth: A systematic review of the empirical evidence.

The objective of this study was to systematically review the available empirical evidence examining associations between preterm birth (PTB) and five domains of place-based contextual social and environmental determinants, including (1) physical environment, (2) residential greenness, (3) neighborhood violence/crime, (4) food accessibility and availability, and (5) health services accessibility, among adult mothers in high-income countries. The evidence in this review suggests an adverse association between damaged physical environment, neighborhood violence/crime, lack of health services accessibility, and PTB. The existing evidence also suggests a beneficial effect of residential greenness on PTB. Further studies are needed to investigate these associations for more understanding of the direction and magnitude of these association and for potential heterogeneity by factors such as race/ethnicity, urban vs rural residence, immigration status, and social class.

Evaluation of a Salt-Reduction Consumer Awareness Campaign Targeted at Parents Residing in the State of Victoria, Australia.

From 2015 to 2020 a state-wide salt-reduction initiative was launched in Victoria, Australia, including an awareness campaign focused on parents with children <18 years of age. To evaluate the impact of the campaign on salt-related knowledge, attitudes and behaviors (KABs) we have assessed trends in salt-related KAB pre- and post-delivery of the campaign in parents, as well as within the wider adult population. Cross-sectional surveys of adults aged 18-65 years were undertaken pre- (2015: n = 821 parents; n = 1527 general sample) and post-campaign (2019: n = 935 parents; n = 1747 general sample). KABs were assessed via an online survey. Data were analyzed with regression models and adjusted for covariates. Among parents, around one-quarter of salt-related KABs shifted in a positive direction, but changes were small: there was a 6% (95% CI 2, 11%) increase in the percentage who knew the main source of salt in the diet and reductions in the percentage who reported placing a salt shaker on the table (-8% (95%CI -12, -3)) and that their child added salt at the table (-5% (95% -9, -0.2)). Among the wider adult sample, even fewer shifts in KAB were observed, with some behaviors worsening at follow-up. These findings indicate that this consumer awareness campaign had minimum impact.

Changes in Pregnancy-Associated Deaths in the US During the COVID-19 Pandemic in 2020.

This cross-sectional study assesses changes in pregnancy-associated mortality from drug overdose, homicide, suicide, and other causes in the US from 2018 through 2020.

Postpartum Medicaid Eligibility Expansions and Postpartum Health Measures.

Maternal mortality and morbidity in the United States are high compared with those in similar countries, and racial/ethnic disparities exist, with many of these events occurring in the later postpartum period. Proposed federal and recently enacted state policy interventions extend pregnancy Medicaid from covering 60 days to a full year postpartum. This study estimates the association between maintaining Medicaid eligibility in the later postpartum period (relative to only having pregnancy Medicaid eligibility) with postpartum checkup attendance and depressive symptoms using regression analysis, overall and stratified by race/ethnicity. People with postpartum Medicaid eligibility were 1.0%-1.4% more likely to attend a postpartum checkup relative to those with only pregnancy Medicaid eligibility overall, primarily driven by a 3.8%-4.0% higher likelihood among Hispanic postpartum people. Conversely, postpartum Medicaid is associated with a 2.2%-2.3% lower likelihood of postpartum checkup attendance for Black postpartum people. Postpartum eligibility is also associated with a 9.7%-11.6% lower likelihood of self-reported depressive symptoms compared with only pregnancy Medicaid eligibility for White postpartum people only. Postpartum Medicaid eligibility is associated with some improvements in maternal health care utilization and mental health, but differences by race and ethnicity imply that inequitable systems and structures that cannot be overcome by insurance alone may also play an important role in postpartum health.

Medicaid expansions and differences in guideline-adherent cervical cancer screening between American Indian and White women.

BACKGROUND: Although preventable through screening, cervical cancer incidence and mortality are higher among American Indian and Alaska Native women (AIAN) than White women. The Patient Protection and Affordable Care Act's (ACA) Medicaid expansions may uniquely impact access and use of cervical cancer screening among AIAN women and ultimately alleviate this disparity. METHODS: Using Medicaid eligible AIAN (N = 4681) and White (N = 57,661) women aged 18-64 years from the 2010-2020 Behavioral Risk Factor Surveillance System, we implemented difference-in-differences regression to estimate the association between the Medicaid expansions and guideline-adherent cervical cancer screening and health care coverage. RESULTS: The Medicaid expansions were not associated with guideline-adherent cervical cancer screening (AIAN: -1 percentage point [ppt] [95% confidence interval, CI: -4, 2 ppts]; White: 3 ppts [95% CI: -0, 6 ppts]), but were associated with a 2 ppt increase (95% CI: 0, 4 ppt) in having had a pap test in the last 5 years among White women. The Medicaid expansions were also associated with increases in having a health plan (AIAN: 5 ppts [95% CI: 1, 9]; White: 11 ppts [95% CI: 7, 15]) and decreases in avoiding medical care due to costs (AIAN: -8 ppts [95% CI: -13, -2]; White: -6 ppts [95% CI: -9, -4]). CONCLUSIONS: While we observed improvements in health care coverage, we did not observe changes to guideline-adherent cervical cancer screening following the ACA's Medicaid expansions. Given the disproportionate burden of cervical cancer among AIAN women, identifying ways to improve cervical cancer screening uptake and delivery should be prioritized to reduce preventable deaths.

Inequalities in cesarean births between American Indian & Alaska Native people and White people.

OBJECTIVE: To explore population-level American Indian & Alaska Native-White inequalities in cesarean birth incidence after accounting for differences in cesarean indication, age, and other individual-level risk factors. DATA SOURCES AND STUDY SETTING: We used birth certificate data inclusive of all live births within the United States between January 1 and December 31, 2017. STUDY DESIGN: We calculated propensity score weights that simultaneously incorporate age, cesarean indication, and clinical and obstetric risk factors to estimate the American Indian and Alaska Native-White inequality. DATA COLLECTION/EXTRACTION METHODS: Births to individuals identified as American Indian, Alaska Native, or White, and residing in one of the 50 US states or the District of Columbia were included. Births were excluded if missing maternal race/ethnicity or any other covariate. PRINCIPAL FINDINGS: After weighing the American Indian and Alaska Native obstetric population to be comparable to the distribution of cesarean indication, age, and clinical and obstetric risk factors of the White population, the cesarean incidence among American Indian and Alaska Natives increased to 33.4% (95% CI: 32.0-34.8), 3.2 percentage points (95% CI: 1.8-4.7) higher than the observed White incidence. After adjustment, cesarean birth incidence remained higher and increased in magnitude among American Indian and Alaska Natives in Robson groups 1 (low risk, primary), 6 (nulliparous, breech presentation), and 9 (transverse/oblique lie). CONCLUSIONS: The unadjusted lower cesarean birth incidence observed among American Indian and Alaska Native individuals compared to White individuals may be related to their younger mean age at birth. After adjusting for this demographic difference, we demonstrate that American Indian and Alaska Native individuals undergo cesarean birth more frequently than White individuals with similar risk profiles, particularly within the low-risk Robson group 1 and those with non-cephalic presentations (Robson groups 6 and 9). Racism and bias in clinical decision making, structural racism, colonialism, or other unidentified factors may contribute to this inequality.

Selection in utero against male twins in the United States early in the COVID-19 pandemic.

OBJECTIVES: We aim to contribute to the literature reporting tests of selection in utero. The theory of reproductive suppression predicts that natural selection would conserve mechanisms, referred to collectively as selection in utero, that spontaneously abort fetuses unlikely to thrive as infants in the prevailing environment. Tests of this prediction include reports that women give birth to fewer than expected male twins, historically among the frailest of infants, during stressful times. The onset of the COVID-19 pandemic in the United States in Spring 2020 demonstrably stressed the population. We test the hypothesis that conception cohorts in gestation at the onset of the pandemic in the United States yielded fewer than expected live male twin births. METHODS: We retrieved deidentified data on the universe of live births in the United States from the National Center for Health Statistics birth certificate records. We applied Box-Jenkins time-series methods to the twin secondary sex ratio computed for 77 monthly conception cohorts spanning August 2013 to December 2019 to detect outlying cohorts in gestation at the onset of the pandemic. RESULTS: The twin secondary sex ratio fell below expected values in three conception cohorts (i.e., July, September, and October 2019, all p < .05) exposed in utero to the onset of the pandemic. CONCLUSIONS: Our results add to prior findings consistent with selection in utero. The role of selection in utero in shaping the characteristics of live births cohorts, especially during the COVID-19 pandemic, warrants further scrutiny.

Exposure to the early COVID-19 pandemic and early, moderate and overall preterm births in the United States: A conception cohort approach.

BACKGROUND: The United States (US) data suggest fewer-than-expected preterm births in 2020, but no study has examined the impact of exposure to the early COVID-19 pandemic at different points in gestation on preterm birth. OBJECTIVE: Our objective was to determine-among cohorts exposed to the early COVID-19 pandemic-whether observed counts of overall, early and moderately preterm birth fell outside the expected range. METHODS: We used de-identified, cross-sectional, national birth certificate data from 2014 to 2020. We used month and year of birth and gestational age to estimate month of conception for birth. We calculated the count of overall (<37 weeks gestation), early (<33 weeks gestation) and moderately (33 to <37 weeks gestation) preterm birth by month of conception. We employed time series methods to estimate expected counts of preterm birth for exposed conception cohorts and identified cohorts for whom the observed counts of preterm birth fell outside the 95% detection interval of the expected value. RESULTS: Among the 23,731,146 births in our study, the mean prevalence of preterm birth among monthly conception cohorts was 9.7 per 100 live births. Gestations conceived in July, August or December of 2019-that is exposed to the early COVID-19 pandemic in the first or third trimester-yielded approximately 3245 fewer moderately preterm and 3627 fewer overall preterm births than the expected values for moderate and overall preterm. Gestations conceived in August and October of 2019-that is exposed to the early COVID-19 pandemic in the late second to third trimester-produced approximately 498 fewer early preterm births than the expected count for early preterm. CONCLUSIONS: Exposure to the early COVID-19 pandemic may have promoted longer gestation among close-to-term pregnancies, reduced risk of later preterm delivery among gestations exposed in the first trimester or induced selective loss of gestations.