Findings

Beginning at conception

Kevin Lewis

April 26, 2016

Changes in Adolescents' Receipt of Sex Education, 2006–2013

Laura Lindberg, Isaac Maddow-Zimet & Heather Boonstra

Journal of Adolescent Health, forthcoming

Methods: Using nationally representative data from the 2006–2010 and 2011–2013 National Survey of Family Growth, we estimated changes over time in adolescents' receipt of sex education from formal sources and from parents and differentials in these trends by adolescents' gender, race/ethnicity, age, and place of residence.

Results: Between 2006–2010 and 2011–2013, there were significant declines in adolescent females' receipt of formal instruction about birth control (70% to 60%), saying no to sex (89% to 82%), sexually transmitted disease (94% to 90%), and HIV/AIDS (89% to 86%). There was a significant decline in males' receipt of instruction about birth control (61% to 55%). Declines were concentrated among adolescents living in nonmetropolitan areas. The proportion of adolescents talking with their parents about sex education topics did not change significantly. Twenty-one percent of females and 35% of males did not receive instruction about methods of birth control from either formal sources or a parent.

Conclusions: Declines in receipt of formal sex education and low rates of parental communication may leave adolescents without instruction, particularly in nonmetropolitan areas. More effort is needed to understand this decline and to explore adolescents' potential other sources of reproductive health information.

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Area-level mortality and morbidity predict ‘abortion proportion’ in England and Wales

Sandra Virgo & Rebecca Sear

Evolution and Human Behavior, forthcoming

Abstract:
Life history theory predicts that where mortality/morbidity is high, earlier reproduction will be favoured. A key component of reproductive decision-making in high income contexts is induced abortion. Accordingly, relationships between mortality/morbidity and ‘abortion proportion’ (proportion of conceptions ending in abortion) are explored at small-area (‘ward’) level in England and Wales. It is predicted that where mortality/morbidity is high, there will be a lower ‘abortion proportion’ in younger women (< 25 years), adjusting for education, unemployment, income, housing tenure and population density. Results show that this prediction is supported: wards with both shorter life expectancy and a higher proportion of people with a limiting long-standing illness have lower abortion proportions in under 25s. In older age bands, in contrast, elevated mortality and morbidity are mostly associated with a higher ‘abortion proportion’. Further, morbidity appears to have a larger effect than mortality on ‘abortion proportion’ in the under-25 age band, perhaps because a) morbidity is more salient than mortality in high-income contexts, and/or b) young women are influenced by health of potential female alloparents when scheduling fertility.

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Shared risk aversion in spontaneous and induced abortion

Ralph Catalano et al.

Human Reproduction, May 2016, Pages 1113-1119

What is known already: Much literature speculates that natural selection conserved risk aversion because the trait enhanced Darwinian fitness. Risk aversion, moreover, supposedly influences all decisions including those that individuals can and cannot report making. We argue that these circumstances, if real, would manifest in conscious and non-conscious decisions to invest in prospective offspring, and therefore affect incidence of induced and spontaneous abortion over time.

Study design, size, duration: Using data from Denmark, we test the hypothesis that monthly conception cohorts yielding unexpectedly many non-clinically indicated induced abortions also yield unexpectedly many spontaneous abortions. The 180 month test period (January 1995 through December 2009), yielded 1 351 800 gestations including 156 780 spontaneous as well as 233 280 induced abortions 9100 of which were clinically indicated.

Participants/materials, setting, methods: We use Box–Jenkins transfer functions to adjust the incidence of spontaneous and non-clinically indicated induced abortions for autocorrelation (including seasonality), cohort size, and fetal as well as gestational anomalies over the 180-month test period. We use cross-correlation to test our hypothesized association.

Main results and the role of chance: We find a positive association between spontaneous and non-clinically indicated induced abortions. This suggests, consistent with our theory, that mothers of conception cohorts that yielded more spontaneous abortions than expected opted more frequently than expected for non-clinically indicated induced abortion.

Wider implications of the findings: Our findings imply that abortion, intentional or ‘spontaneous,’ follows from a woman's estimate, made consciously or otherwise, of the costs and benefits of extending gestation given characteristics of the prospective offspring, likely environmental circumstances at birth, and maternal resources.

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Spontaneous Pregnancy Loss in Denmark Following Economic Downturns

Tim Bruckner, Laust Mortensen & Ralph Catalano

American Journal of Epidemiology, 15 April 2016, Pages 701-708

Abstract:
An estimated 11%–20% of clinically recognized pregnancies result in spontaneous abortion. The literature finds elevated risk of spontaneous abortion among women who report adverse financial life events. This work suggests that, at the population level, national economic decline — an ambient and plausibly unexpected stressor — will precede an increase in spontaneous abortion. We tested this hypothesis using high-quality information on pregnancy and spontaneous loss for all women in Denmark. We applied time-series methods to monthly counts of clinically detected spontaneous abortions (n = 157,449) and the unemployment rate in Denmark beginning in January 1995 and ending in December 2009. Our statistical methods controlled for temporal patterns in spontaneous abortion (e.g., seasonality, trend) and changes in the population of pregnancies at risk of loss. Unexpected increases in the unemployment rate preceded by 1 month a rise in the number of spontaneous abortions (β = 33.19 losses/month, 95% confidence interval: 8.71, 57.67). An attendant analysis that used consumption of durable household goods as an indicator of financial insecurity supported the inference from our main test. Changes over time in elective abortions and in the cohort composition of high-risk pregnancies did not account for results. It appears that in Denmark, ambient stressors as common as increasing unemployment may precede a population-level increase in spontaneous abortion.

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Women's Knowledge of and Support for Abortion Restrictions in Texas: Findings from a Statewide Representative Survey

Kari White et al.

Perspectives on Sexual and Reproductive Health, forthcoming

Context: States have passed numerous laws restricting abortion, and Texas passed some of the most restrictive legislation between 2011 and 2013. Information about women's awareness of and support for the laws’ provisions could inform future debates regarding abortion legislation.

Methods: Between December 2014 and January 2015, some 779 women aged 18–49 participated in an online, statewide representative survey about recent abortion laws in Texas. Poisson regression analysis was used to assess correlates of support for a law that would make obtaining an abortion more difficult. Women's knowledge of specific abortion restrictions in Texas and reasons for supporting these laws were also assessed.

Results: Overall, 31% of respondents would support a law making it more difficult to obtain an abortion. Foreign-born Latinas were more likely than whites to support such a law (prevalence ratio, 1.5), and conservative Republicans were more likely than moderates and Independents to do so (2.3). Thirty-six percent of respondents were not very aware of recent Texas laws, and 19% had never heard of them. Among women with any awareness of the laws, 19% supported the requirements; 42% of these individuals said this was because such laws would make abortion safer.

Conclusions: Many Texas women of reproductive age are unaware of statewide abortion restrictions, and some support these requirements because of misperceptions about the safety of abortion. Advocates and policymakers should address these knowledge gaps in efforts to protect access to legal abortion.

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Physical and neurobehavioral determinants of reproductive onset and success

Felix Day et al.

Nature Genetics, forthcoming

Abstract:
The ages of puberty, first sexual intercourse and first birth signify the onset of reproductive ability, behavior and success, respectively. In a genome-wide association study of 125,667 UK Biobank participants, we identify 38 loci associated (P < 5 × 10−8) with age at first sexual intercourse. These findings were taken forward in 241,910 men and women from Iceland and 20,187 women from the Women's Genome Health Study. Several of the identified loci also exhibit associations (P < 5 × 10−8) with other reproductive and behavioral traits, including age at first birth (variants in or near ESR1 and RBM6–SEMA3F), number of children (CADM2 and ESR1), irritable temperament (MSRA) and risk-taking propensity (CADM2). Mendelian randomization analyses infer causal influences of earlier puberty timing on earlier first sexual intercourse, earlier first birth and lower educational attainment. In turn, likely causal consequences of earlier first sexual intercourse include reproductive, educational, psychiatric and cardiometabolic outcomes.

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Impact of Clinic Closures on Women Obtaining Abortion Services After Implementation of a Restrictive Law in Texas

Caitlin Gerdts et al.

American Journal of Public Health, May 2016, Pages 857-864

Objectives: To evaluate the additional burdens experienced by Texas abortion patients whose nearest in-state clinic was one of more than half of facilities providing abortion that had closed after the introduction of House Bill 2 in 2013.

Methods: In mid-2014, we surveyed Texas-resident women seeking abortions in 10 Texas facilities (n = 398), including both Planned Parenthood–affiliated clinics and independent providers that performed more than 1500 abortions in 2013 and provided procedures up to a gestational age of at least 14 weeks from last menstrual period. We compared indicators of burden for women whose nearest clinic in 2013 closed and those whose nearest clinic remained open.

Results: For women whose nearest clinic closed (38%), the mean one-way distance traveled was 85 miles, compared with 22 miles for women whose nearest clinic remained open (P ≤ .001). After adjustment, more women whose nearest clinic closed traveled more than 50 miles (44% vs 10%), had out-of-pocket expenses greater than $100 (32% vs 20%), had a frustrated demand for medication abortion (37% vs 22%), and reported that it was somewhat or very hard to get to the clinic (36% vs 18%; P < .05).

Conclusions: Clinic closures after House Bill 2 resulted in significant burdens for women able to obtain care.

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What do men want? Re-examining whether men benefit from higher fertility than is optimal for women

Cristina Moya, Kristin Snopkowski & Rebecca Sear

Philosophical Transactions of the Royal Society: Biological Sciences, 19 April 2016

Abstract:
Several empirical observations suggest that when women have more autonomy over their reproductive decisions, fertility is lower. Some evolutionary theorists have interpreted this as evidence for sexual conflicts of interest, arguing that higher fertility is more adaptive for men than women. We suggest the assumptions underlying these arguments are problematic: assuming that women suffer higher costs of reproduction than men neglects the (different) costs of reproduction for men; the assumption that men can repartner is often false. We use simple models to illustrate that (i) men or women can prefer longer interbirth intervals (IBIs), (ii) if men can only partner with wives sequentially they may favour shorter IBIs than women, but such a strategy would only be optimal for a few men who can repartner. This suggests that an evolved universal male preference for higher fertility than women prefer is implausible and is unlikely to fully account for the empirical data. This further implies that if women have more reproductive autonomy, populations should grow, not decline. More precise theoretical explanations with clearly stated assumptions, and data that better address both ultimate fitness consequences and proximate psychological motivations, are needed to understand under which conditions sexual conflict over reproductive timing should arise.

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Association Between High Ambient Temperature and Risk of Stillbirth in California

Rupa Basu, Varada Sarovar & Brian Malig

American Journal of Epidemiology, forthcoming

Abstract:
Recent studies have linked elevated apparent temperatures with adverse birth outcomes, such as preterm delivery, but other birth outcomes have not been well studied. We examined 8,510 fetal deaths (≥20 weeks’ gestation) to estimate their association with mean apparent temperature, a combination of temperature and humidity, during the warm season in California (May–October) from 1999 to 2009. Mothers whose residential zip codes were within 10 km of a meteorological monitor were included. Meteorological data were provided by the California Irrigation Management Information System, the US Environmental Protection Agency, and the National Climatic Data Center, while the California Department of Public Health provided stillbirth data. Using a time-stratified case-crossover study design, we found a 10.4% change (95% confidence interval: 4.4, 16.8) in risk of stillbirth for every 10°F (5.6°C) increase in apparent temperature (cumulative average of lags 2–6 days). Risk varied by maternal race/ethnicity and was greater for younger mothers, less educated mothers, and male fetuses. The highest risks were observed during gestational weeks 20–25 and 31–33. No associations were found during the cold season (November–April), and the observed associations were independent of air pollutants. This study adds to the growing body of literature identifying pregnant women and their fetuses as subgroups vulnerable to heat exposure.

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Reproductive history and post-reproductive mortality: A sibling comparison analysis using Swedish register data

Kieron Barclay et al.

Social Science & Medicine, April 2016, Pages 82–92

Abstract:
A growing body of evidence suggests that reproductive history influences post-reproductive mortality. A potential explanation for this association is confounding by socioeconomic status in the family of origin, as socioeconomic status is related to both fertility behaviours and to long-term health. We examine the relationship between age at first birth, completed parity, and post-reproductive mortality and address the potential confounding role of family of origin. We use Swedish population register data for men and women born 1932-1960, and examine both all-cause and cause-specific mortality. The contributions of our study are the use of a sibling comparison design that minimizes residual confounding from shared family background characteristics and assessment of cause-specific mortality that can shed light on the mechanisms linking reproductive history to mortality. Our results were entirely consistent with previous research on this topic, with teenage first time parents having higher mortality, and the relationship between parity and mortality following a U-shaped pattern where childless men and women and those with five or more children had the highest mortality. These results indicate that selection into specific fertility behaviours based upon socioeconomic status and experiences within the family of origin does not explain the relationship between reproductive history and post-reproductive mortality. Additional analyses where we adjust for other lifecourse factors such as educational attainment, attained socioeconomic status, and post-reproductive marital history do not change the results. Our results add an important new level of robustness to the findings on reproductive history and mortality by showing that the association is robust to confounding by factors shared by siblings. However it is still uncertain whether reproductive history causally influences health, or whether other confounding factors such as childhood health or risk-taking propensity could explain the association.

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Status competition, inequality, and fertility: Implications for the demographic transition

Mary Shenk, Hillard Kaplan & Paul Hooper

Philosophical Transactions of the Royal Society: Biological Sciences, 19 April 2016

Abstract:
The role that social status plays in small-scale societies suggests that status may be important for understanding the evolution of human fertility decisions, and for understanding how such decisions play out in modern contexts. This paper explores whether modelling competition for status — in the sense of relative rank within a society — can help shed light on fertility decline and the demographic transition. We develop a model of how levels of inequality and status competition affect optimal investment by parents in the embodied capital (health, strength, and skills) and social status of offspring, focusing on feedbacks between individual decisions and socio-ecological conditions. We find that conditions similar to those in demographic transition societies yield increased investment in both embodied capital and social status, generating substantial decreases in fertility, particularly under conditions of high inequality and intense status competition. We suggest that a complete explanation for both fertility variation in small-scale societies and modern fertility decline will take into account the effects of status competition and inequality.


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