Julia Goodman

Juggling Work and Breastfeeding: Effects of Maternity Leave and Occupational Characteristics

OBJECTIVES. Juggling breastfeeding and paid work can challenge breastfeeding success. We examined the relationship between breastfeeding and maternity leave before and after delivery among working mothers in Southern California. California is 1 of only 5 states in the United States providing paid pregnancy leave that can be extended for infant bonding. PATIENTS AND METHODS. Drawing from a case-control study of preterm birth and low birth weight, 770 full-time working mothers were compared on whether they established breastfeeding in the first month. For those who established breastfeeding, we examined duration. Eligible women participated in Californias Prenatal Screening Program; delivered live births between July 2002 and December 2003; were ≥18 years old; had a singleton birth without congenital anomalies; and had a US mailing address. We assessed whether maternity leave and other occupational characteristics predicted breastfeeding cessation and used multivariate regression models weighted for probability of sampling to calculate odds ratios for breastfeeding establishment and hazards ratios for breastfeeding cessation. RESULTS. A maternity leave of ≤6 weeks or 6 to 12 weeks after delivery was associated, respectively, with a fourfold and twofold higher odds of failure to establish breastfeeding and an increased probability of cessation after successful establishment, relative to women not returning to work, after adjusting for covariates. The impact of short postpartum leave on breastfeeding cessation was stronger among nonmanagers, women with inflexible jobs, and with high psychosocial distress. Antenatal leave in the last month of pregnancy was not associated with breastfeeding establishment or duration. CONCLUSIONS. Postpartum maternity leave may have a positive effect on breastfeeding among full-time workers, particularly those who hold nonmanagerial positions, lack job flexibility, or experience psychosocial distress. Pediatricians should encourage patients to take maternity leave and advocate for extending paid postpartum leave and flexibility in working conditions for breastfeeding women.

Selection against small males in utero: a test of the Wells hypothesis

BACKGROUND The argument that women in stressful environments spontaneously abort their least fit fetuses enjoys wide dissemination despite the fact that several of its most intuitive predictions remain untested. The literature includes no tests, for example, of the hypothesis that these mechanisms select against small for gestational age (SGA) males. METHODS We apply time-series modeling to 4.9 million California male term births to test the hypothesis that the rate of SGA infants in 1096 weekly birth cohorts varies inversely with labor market contraction, a known stressor of contemporary populations. RESULTS We find support for the hypothesis that small size becomes less frequent among term male infants when the labor market contracts. CONCLUSIONS Our findings contribute to the evidence supporting selection in utero. They also suggest that research into the association between maternal stress and adverse birth outcomes should acknowledge the possibility that fetal loss may affect findings and their interpretation. Strengths of our analyses include the large number and size of our birth cohorts and our control for autocorrelation. Weaknesses include that we, like nearly all researchers in the field, have no direct measure of fetal loss.

Natural selection in utero induced by mass layoffs: the hCG evidence

Evolutionary theory, when coupled with research from epidemiology, demography, and population endocrinology, suggests that contracting economies affect the fitness and health of human populations via natural selection in utero. We know, for example, that fetal death increases more among males than females when the economy unexpectedly contracts; that unexpected economic contraction predicts low secondary sex ratios; and that males from low sex ratio birth cohorts live, on average, longer than those from high sex ratio cohorts. We also know that low levels of human chorionic gonadotropin (i.e., hCG) measured in the serum of pregnant women predict fetal death. We do not, however, know whether male survivors of conception cohorts subjected to contracting economies exhibit, as theory predicts, higher hCG than those from other cohorts. We show, in 71 monthly conception cohorts including nearly two million California births, that they do. We thereby add to the literature suggesting that the economy, a phenomenon over which we collectively exercise at least some control, affects population health. Our findings imply that the effect arises via natural selection – a mechanism we largely ignore when attempting to explain, or alter, how collective choice affects our biology.

Timing of birth: Parsimony favors strategic over dysregulated parturition

The “dysregulated parturition” narrative posits that the human stress response includes a cascade of hormones that “dysregulates” and accelerates parturition but provides questionable utility as a guide to understand or prevent preterm birth. We offer and test a “strategic parturition” narrative that not only predicts the excess preterm births that dysregulated parturition predicts but also makes testable, sex‐specific predictions of the effect of stressful environments on the timing of birth among term pregnancies.

Twins less frequent than expected among male births in risk averse populations.

Male twin gestations exhibit higher incidence of fetal morbidity and mortality than singleton gestations. From an evolutionary perspective, the relatively high rates of infant and child mortality among male twins born into threatening environments reduce the fitness of these gestations, making them more vulnerable to fetal loss. Women do not perceive choosing to spontaneously abort gestations although the outcome may result from estimates, made without awareness, of the risks of continuing a pregnancy. Here, we examine whether the non-conscious decisional biology of gestation can be linked to conscious risk aversion. We test this speculation by measuring the association between household surveys in Sweden that gauge financial risk aversion in the population and the frequency of twins among live male births. We used time-series regression methods to estimate our suspected associations and Box-Jenkins modeling to ensure that autocorrelation did not confound the estimation or reduce its efficiency. We found, consistent with theory, that financial risk aversion in the population correlates inversely with the odds of a twin among Swedish males born two months later. The odds of a twin among males fell by approximately 3.5% two months after unexpectedly great risk aversion in the population. This work implies that shocks that affect population risk aversion carry implications for fetal loss in vulnerable twin pregnancies.

Stroke-attributable death among older persons during the great recession.

Epidemiological evidence indicates an elevated risk for stroke among stressed persons, in general, and among individuals who have lost their job, in particular. We, therefore, tested the hypothesis that stroke accounted for a larger fraction of deaths during the Great Recession than expected from other deaths and from trends, cycles, and other forms of autocorrelation. Based on vital statistics death data from California spanning 132 months from January 2000 through December 2010, we found support for the hypothesis. These findings appear attributable to non-Hispanic white men, who experienced a 5% increase in their monthly odds of stroke-attributable death. Total mortality in this group, however, did not increase. Findings suggest that 879 deaths among older white men shifted from other causes to stroke during the 36 months following the start of the Great Recession. We infer the Great Recession may have affected social, biologic, and behavioral risk factors that altered the life histories of older white men in ways that shifted mortality risk toward stroke.

Post-term birth as a response to environmental stress The case of September 11, 2001

Background and objectives: Despite growing interest in the role of maternal psychosocial stress as a determinant of preterm birth, no existing work has examined the relation between maternal stress and post-term birth (≥42 weeks). We hypothesize that prolonging gestation past term may represent an adaptive strategy to a suboptimal environment. Methodology: We examined the relationship between exposure to the September 2001 terrorist attacks and odds of post-term birth in California. We calculated the expected odds of post-term birth among conception cohorts of singleton gestations in California between October 1996 and November 2005. We used time series analysis to test for higher than expected odds of post-term birth among the 10 cohorts exposed to the attacks of September 2001 (those conceived from December 2000 to September 2001). Results: The observed odds of post-term delivery among gestations at 33–36 weeks in September 2001 were higher than statistically expected for all race/ethnic and sex groups. Conclusions and implications: Our finding that odds of post-term birth were higher than expected among pregnancies exposed to the September 2001 terrorist attacks in late gestation provides initial support for the hypothesis that exposure to a psychosocial stress during pregnancy may result in prolonged gestation.

Antenatal Maternity Leave and Childbirth Using the First Baby Study: A Propensity Score Analysis

BACKGROUND Most employed American women work during pregnancy and continue working through the month they deliver. Yet, few studies estimate the relationship between maternity leave taken during pregnancy and maternal health. We evaluate the association of antenatal leave (ANL) uptake with obstetric outcomes, assessing the potential role of protective and adverse selection pathways on this relationship. METHODS We sample 1,740 employed women who delivered at term from the First Baby Study, a prospective cohort of nulliparous women in Pennsylvania. We use propensity scores to estimate the relationship between ANL and negative delivery outcomes (labor induction, long labor duration, unplanned cesarean delivery, and self-reported negative birth experience). We estimated propensity scores using a range of employment, health, and sociodemographic variables. RESULTS One-half of the sampled women worked until the day before or day of delivery. Women who stopped working at least 2 days before delivery experienced 16% more negative delivery outcomes, on average, than women who worked until delivery, driven largely by a 25% higher predicted probability of unplanned cesarean section deliveries. These robust findings hold up to a range of sensitivity analyses and demonstrate selective mechanisms operating in ANL uptake. CONCLUSION Our findings suggest that, even after controlling for an extensive set of observable employment, health, and sociodemographic characteristics, women who take ANL continue to differ in unobserved characteristics that lead to negative delivery outcomes. Like most U.S. states, Pennsylvania does not grant paid maternity leave. In a context of limited maternity leave availability, only relatively unhealthy women take ANL.

Laboring Until Labor: The Prevalence and Correlates of Antenatal Maternity Leave in the United States

Introduction Most women in the U.S. are employed during pregnancy and work until the month of childbirth. For many, working throughout pregnancy poses little threat to their health; however, women experiencing difficult pregnancies and/or working in strenuous or inflexible jobs may benefit from taking time from work as they approach childbirth, but almost no empirical evidence examines antenatal leave (ANL). Methods Using a national survey of English-speaking women, this paper offers the first national description of ANL and examines state policy predictors of uptake. Results Thirty-seven percent of employed women worked until the week their baby was due. After controlling for characteristics of women and their jobs, living in a state with any or multiple leave laws increased the probability of ANL by 14 and 23% points, respectively. Women living in states with multiple leave laws stopped work almost 2 weeks earlier than women in states without a policy. Discussion Paid leave policies currently being considered at the federal, state, and local levels should consider the potential impact on antenatal leave, in addition to postnatal leave, and how they influence population health.