Prenatal
Prescient Human Fetuses Thrive
Curt Sandman, Elysia Poggi Davis & Laura Glynn
Psychological Science, forthcoming
Abstract:
Fetal detection of adversity is a conserved trait that allows many species to adapt their early developmental trajectories to ensure survival. According to the fetal-programming model, exposure to stressful or hostile conditions in utero is associated with compromised development and a lifelong risk of adverse health outcomes. In a longitudinal study, we examined the consequences of prenatal and postnatal exposure to adversity for infant development. We found increased motor and mental development during the 1st year of life among infants whose mothers experienced congruent levels of depressive symptoms during and after pregnancy, even when the levels of symptoms were relatively high and the prenatal and postnatal environments were unfavorable. Congruence between prenatal and postnatal environments prepares the fetus for postnatal life and confers an adaptive advantage for critical survival functions during early development.
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Utilization of Infertility Treatments: The Effects of Insurance Mandates
Marianne Bitler & Lucie Schmidt
NBER Working Paper, December 2011
Abstract:
Over the last several decades, both delay of childbearing and fertility problems have become increasingly common among women in developed countries. At the same time, technological changes have made many more options available to individuals experiencing fertility problems. However, these technologies are expensive, and only 25% of health insurance plans in the United States cover infertility treatment. As a result of these high costs, legislation has been passed in 15 states that mandates insurance coverage of infertility treatment in private insurance plans. In this paper, we examine whether mandated insurance coverage for infertility treatment affects utilization. We allow utilization effects to differ by age and education, since previous research suggests that older, more educated women should be more likely to be directly affected by the mandates than younger women and less educated women, both because they are at higher risk of fertility problems and because they are more likely to have private health insurance which is subject to the mandate. We find robust evidence that the mandates do have a significant effect on utilization for older, more educated women that is larger than the effects found for other groups. These effects are largest for the use of ovulation-inducing drugs and artificial insemination.
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Arthur Greil et al.
Journal of Health and Social Behavior, December 2011, Pages 493-509
Abstract:
Evidence of group differences in reproductive control and access to reproductive health care suggests the continued existence of "stratified reproduction" in the United States. Women of color are overrepresented among people with infertility but are underrepresented among those who receive medical services. The authors employ path analysis to uncover mechanisms accounting for these differences among black, Hispanic, Asian, and non-Hispanic white women using a probability-based sample of 2,162 U.S. women. Black and Hispanic women are less likely to receive services than other women. The enabling conditions of income, education, and private insurance partially mediate the relationship between race-ethnicity and receipt of services but do not fully account for the association at all levels of service. For black and Hispanic women, social cues, enabling conditions, and predisposing conditions contribute to disparities in receipt of services. Most of the association between race-ethnicity and service receipt is indirect rather than direct.
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Linn Strand, Adrian Barnett & Shilu Tong
American Journal of Epidemiology, forthcoming
Abstract:
Almost 10% of all births are preterm, and 2.2% are stillbirths. Recent research has suggested that environmental factors may be a contributory cause of these adverse birth outcomes. The authors examined the relation between ambient temperature and preterm birth and stillbirth in Brisbane, Australia, between 2005 and 2009 (n = 101,870). They used a Cox proportional hazards model with livebirth and stillbirth as competing risks. They also examined whether there were periods in pregnancy where exposure to high temperatures had a greater effect. Higher ambient temperatures in the last 4 weeks of the pregnancy increased the risk of stillbirth. The hazard ratio for stillbirth was 0.3 at 12°C relative to the reference temperature of 21°C. The temperature effect was greatest at less than 36 weeks of gestation. There was an association between higher temperature and shorter gestation, as the hazard ratio for livebirth was 0.96 at 15°C and 1.02 at 25°C. This effect was greatest at later gestational ages. These results provide strong evidence of an association between increased temperature and increased risk of stillbirth and shorter gestation.
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From Infant to Mother: Early Disease Environment and Future Maternal Health
Douglas Almond, Janet Currie & Mariesa Herrmann
NBER Working Paper, December 2011
Abstract:
This paper examines the links between the disease environment around the time of a woman's birth, and her health at the time she delivers her own infant. Our results suggest that exposure to disease in early childhood significantly increases the incidence of diabetes in the population of future mothers. The exposed mothers are less likely to be married, have fewer years of education, are more likely to gain over 60 pounds while pregnant, and are more likely to smoke while pregnant. Not surprisingly then, exposure increases the probability of low birth weight in the next generation, at least among whites. Among whites, this effect remains when we control for maternal behaviors as well as disease exposure. Among blacks, we find that maternal exposure reduces the incidence of low birth weight. The difference between whites and blacks may reflect a "scarring" vs. selection story; whites who go on to have children are negatively impacted, while blacks who go on to have children are positively selected having survived a higher early childhood mortality rate.
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Long-run effects of fetal influenza exposure: Evidence from Switzerland
Sven Neelsen & Thomas Stratmann
Social Science & Medicine, January 2012, Pages 58-66
Abstract:
In this paper we estimate long-run effects of fetal exposure to the 1918/19 influenza pandemic for a European country. Using data from the 1970 Swiss census, we find that the male 1919 cohort that had a strongly increased likelihood of fetal exposure to the pandemic performs significantly worse in terms of educational attainment and has a lower chance of marriage than the surrounding cohorts. Further, we find similar results when we in addition use regional differences in influenza severity to test for the impact of influenza on later-life outcomes. A set of robustness tests confirm our findings.
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Howard Chang, Brian Reich & Marie Lynn Miranda
American Journal of Epidemiology, forthcoming
Abstract:
Exposure to air pollution during pregnancy has been suggested to be a risk factor for preterm birth; however, epidemiologic evidence remains mixed and limited. The authors examined the association between ambient levels of particulate matter <2.5 μm in aerodynamic diameter (PM2.5) and the risk of preterm birth in North Carolina during the period 2001-2005. They estimated the risks of cumulative and lagged average exposures to PM2.5 during pregnancy via a 2-stage discrete-time survival model. The authors also considered exposure metrics derived from 1) ambient concentrations measured by the Air Quality System (AQS) monitoring network and 2) concentrations predicted by statistically fusing AQS data with process-based numerical model output (the Statistically Fused Air and Deposition Surfaces (FSD) database). Using the AQS measurements, an interquartile-range (1.73 μg/m3) increase in cumulative PM2.5 exposure was associated with a 6.8% (95% posterior interval: 0.5, 13.6) increase in the risk of preterm birth. Using the FSD-predicted levels and accounting for prediction error, the authors also found significant adverse associations between trimester 1, trimester 2, and cumulative PM2.5 exposure and preterm birth. These findings suggest that exposure to ambient PM2.5 during pregnancy is associated with increased risk of preterm birth, even in a region characterized by relatively good air quality.
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Florencia Torche & Karine Kleinhaus
Human Reproduction, forthcoming
Background: Previous research suggests that maternal exposure to acute stress has a negative impact on the duration of pregnancy, and that this effect may vary by the time of exposure. It has also been proposed that stress exposure reduces the ratio of male-to-female births. To date, no study has jointly examined both outcomes, although they may be strongly related. Using population-level data with no selectivity, we jointly study the sex-specific effect of stress on the duration of pregnancy and the observed sex ratio among pregnant women exposed to a major earthquake in Chile.
Methods: In a quasi-experimental design, women exposed to the earthquake in different months of gestation were compared with women pregnant 1 year earlier. Estimates from a comparison group of pregnant women living in areas not affected by the earthquake were also examined to rule out confounding trends. Regression models were used to measure the impact of earthquake exposure on gestational age and preterm birth by sex across month of gestation. A counterfactual simulation was implemented to assess the effect of the earthquake on the secondary sex ratio accounting for the differential impact of stress on gestational age by sex.
Results: Earthquake exposure in Months 2 and 3 of gestation resulted in a significant decline in gestational age and increase in preterm delivery. Effects varied by sex, and were much larger for female than male pregnancies. Among females, the probability of preterm birth increased by 0.038 [95% confidence interval (CI): 0.005, 0.072] in Month 2 and by 0.039 (95% CI: 0.002, 0.075) in Month 3. Comparable increases for males were insignificant at the conventional P < 0.05 level. After accounting for the sex-specific impact on gestational age, a decline in the male-to-female ratio in Month 3 of exposure was detected [-0.058 (95% CI: -0.113, -0.003)].
Conclusions: Maternal exposure to an exogenous stressor early but not late in the pregnancy affects gestational age and the probability of preterm birth. This effect is much stronger in females than males. Stress exposure in early pregnancy may also contribute to a decline in the ratio of male-to-female live births in exposed cohorts.
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Zaneta Thayer, Alan Feranil & Christopher Kuzawa
American Journal of Human Biology, January/February 2012, Pages 1-4
Objectives: Lower birth weight (BW) reoccurs across generations, but the intermediate mechanisms remain poorly understood. One potential pathway involves cortisol, which may be elevated in women born small and in turn could lead to fetal growth restriction in offspring. To test this possibility, we evaluated whether BW predicts hypothalamic-pituitary-adrenal (HPA) function in the nonpregnant state in a cohort of young Filipino women, and whether differences in HPA function predict offspring BW.
Methods: Multiple regression relating maternal BW, adult salivary cortisol profiles and recalled offspring BW (N = 488) among participants of the Cebu Longitudinal Health and Nutrition Survey.
Results: Maternal BW related inversely to evening cortisol in adulthood (P < 0.04). Maternal BW and evening cortisol were both stronger predictors of male than of female BW (maternal BW: P < 0.0001 for males; P = 0.07 for females; bedtime cortisol: P = 0.003 for males; P = 0.3 for females). Waking and 30-min postwaking cortisol did not predict offspring BW. Controlling for evening cortisol did not diminish the relationship between maternal and offspring BW in males or females.
Conclusions: Being born small predicted higher evening cortisol in adulthood among these young mothers. Lower maternal BW and elevated evening cortisol independently predicted giving birth to lower BW offspring, with effects greatest and only significant among males. We speculate that sex differences in sensitivity to maternal stress hormones could help explain the stronger relationships between BW and cardiovascular disease (CVD) risk factors reported among the males in this and other populations.
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A preliminary investigation of synchronous pregnancies in women
K. Worth & Maryanne Fisher
Journal of Evolutionary Psychology, December 2011, Pages 309-326
Abstract:
Menstrual synchrony is when the menstrual cycles of friends or family members coincide, such that women conform to the same cycle. In this paper, we propose the existence of synchronous pregnancies, which may be analogous to menstrual synchrony. Menstrual synchrony is a well-studied topic, whereas synchronous pregnancies among friends or family members is an overlooked area of investigation. In this exploratory study of 81 pregnant women, we hypothesize that women's pregnancies are synchronized with those of friends or family members. We also examine whether women intentionally plan their pregnancies in accordance with these individuals. Finally, we investigate the sharing of resources among women who have simultaneous pregnancies. Our findings suggest that the pregnancies of women are more synchronized with friends than family members, and often the synchronicity is unplanned. The majority of women indicated that they intend to share resources (including parenting) with others who are pregnant at the same time, or who have recently given birth. Using an evolutionary framework, we propose that the sharing of resources is highly valuable and might represent a reason for women to, albeit inadvertently, have synchronized pregnancies.
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Günter Schulter, Walter Goessler & Ilona Papousek
American Journal of Human Biology, January/February 2012, Pages 74-80
Objectives: Mounting evidence indicates that adult health outcomes such as the development of cardiovascular disease or diabetes can trace some of their roots back to prenatal development. This study investigated the epigenetic impact of a particular prenatal hormonal condition on specific health-related consequences, i.e., on concentrations of minerals and mineral metabolism in adults.
Methods: In 70 university students, the second-to-fourth digit length (2D:4D) was measured as a proxy of prenatal sex steroid action, and the concentrations of sodium (Na), potassium (K), magnesium (Mg), and calcium (Ca) were determined in hair samples by inductively coupled plasma-mass spectrometry. Mineral concentrations and the mineral ratios Na/K, Na/Mg, and Na/Ca were analyzed in multivariate analyses of variance, with digit ratios and sex of participants as grouping variables. The results were validated in a replication cohort from the general population, and with a wider age-range. In addition, the correlation of mineral concentrations and mineral ratios with blood pressure was examined.
Results: Men with relatively lower (i.e., more masculine) and women with relatively higher (i.e., more feminine) digit ratios had higher Na/K, Na/Mg, and Na/Ca ratios than their counterparts. Virtually identical results were obtained in the replication study. Moreover, Na concentrations and Na/K ratios were significantly correlated with systolic blood pressure.
Conclusions: The findings suggest that the individual variation in mineral metabolism can be predicted by 2D:4D, indicating that prenatal sex steroid action may be involved in the epigenetic programming of specific metabolic conditions which are highly relevant to adult health and disease.