Maybe babies
Public Perception of Female Fertility: Initial Fertility, Peak Fertility, and Age-Related Infertility Among U.S. Adults
Robin Jensen, Nicole Martins & Melissa Parks
Archives of Sexual Behavior, July 2018, 1507–1516
Abstract:
Perceptions of fertility are thought to impact reproductive behaviors, yet little is known about how lay people conceptualize the female fertility timeline. In this research, public perception of the female fertility timeline was assessed via a national survey of U.S. adults (N = 990) ranging in age from 18 to 89 years. Although there is no scientific consensus on the makeup of the female fertility timeline, results from this research indicate that the U.S. public posits fertility onset at (approximately) 13 years, peak fertility at 22, ideal first pregnancy age at 23, too late for pregnancy at 46, and infertility at 49. Regression analysis revealed that perceived peak fertility and ideal pregnancy age were positively correlated such that participants perceived the ideal pregnancy age as directly following peak fertility. Education was significantly related to fertility perceptions; those with more education perceived initial fertility to be lower and peak fertility and ideal pregnancy age to be higher. In other words, more highly educated individuals perceived fertility to manifest over a longer period of time as compared to individuals with less education. Black and Hispanic participants and participants with lower income perceived ideal first pregnancy age as significantly lower than did White participants and participants with higher income. These differences may suggest that the seeds of health disparities associated with phenomena such as adolescent pregnancy are lurking in fertility timeline perceptions.
Beyond the quantity–quality tradeoff: Population control policy and human capital investment
Xuebo Wang & Junsen Zhang
Journal of Development Economics, forthcoming
Abstract:
The quantity–quality tradeoff theory implies that a reduction in fertility would induce more human capital investment per child, and it is widely believed that population control policy could promote human capital levels in developing countries. China's one-child policy (OCP) has significantly reduced the fertility in the country, and popular belief holds that this policy has contributed to the enhancement in China's human capital since 1979. However, the quantity–quality tradeoff dose not present the complete truth — another crucial factor relates to which segment of the population is reduced, a critical issue that has been ignored in the literature. China's OCP is significantly more strictly implemented in urban areas than in rural areas, where human capital investment in children is significantly lower. This two-tier OCP could have significantly increased the rural–urban fertility ratio and brought about important consequences. We first emphasize the importance of such a population compositional effect, which may offset the potentially positive quantity–quality tradeoff effect on human capital. We present a simple analytic framework and quantify the relative sizes of the quantity–quality tradeoff and compositional effects. We find that the former is dominated by the latter, and that the OCP has reduced the average human capital level of China's next generation by approximately 1–2%. This novel evidence indicates that the conventional wisdom on population control may be incomplete and that its policy implications could be misleading.
Fertility Behavior of Interracial Couples
Kate Choi & Rachel Goldberg
Journal of Marriage and Family, forthcoming
Abstract:
Despite the unprecedented rise in the number of intermarriages and multiracial individuals in recent decades, our understanding about the fertility behavior of interracial couples is limited. Using data from the 2002 and 2006–2015 National Survey of Family Growth, this study compares the risk of pregnancy and the pregnancy intentions of interracial couples with those of same‐race couples. Interracial couples' risk of pregnancy differed little from that of same‐race White couples, with the exception of White wife–Black husband couples, whose risk of pregnancy was higher than both same‐race White and Black couples. Neither socioeconomic disparities nor union characteristics explained their elevated pregnancy risk. Interracial couples' risk of unintended pregnancy mirrored closely that of same‐race couples from the husband's racial or ethnic group. Socioeconomic disparity was the primary driver of differences in pregnancy intentions between interracial and same‐race White couples.
Changes in Alcohol, Tobacco, and Other Drug Use Over Five Years After Receiving Versus Being Denied a Pregnancy Termination
Sarah Roberts et al.
Journal of Studies on Alcohol and Drugs, March 2018, Pages 293–301
Objective: Research on effects of pregnancy termination on women’s alcohol, tobacco, and other drug (ATOD) use suffers from methodological and conceptual problems. Improving on prior methodologies, this study examines changes in ATOD use over 5 years among women seeking terminations.
Method: Data are from the Turnaway Study, a longitudinal study of 956 women seeking terminations at 30 U.S. facilities. Participants presented just below a facility’s gestational limit and received terminations (Near-Limits) or just beyond the limit and were denied terminations (Turnaways). Using mixed-effects logistic regression, we assessed differences in ATOD use over 5 years among Near-Limits and Turnaways.
Results: There were no differences in ATOD use before pregnancy recognition; 1 week after termination seeking, Turnaways had lower odds than Near-Limits of any and heavy episodic alcohol use (p < .001), but not alcohol problem symptoms, tobacco use, or other drug use. Although both groups increased in any alcohol use over time, Turnaways increased more rapidly. Neither group increased any other ATOD measures over time. Turnaways’ lower odds of heavy episodic alcohol use at 1 week after termination seeking were maintained throughout the subsequent 5 years. There was no differential change in problem alcohol use or in tobacco or other drug use over time, yet fewer Turnaways than Near-Limits reported problem alcohol symptoms 6 months through 3.5 years.
Conclusions: There is no indication that terminating a pregnancy led women to increase heavy episodic or problem alcohol use or to increase tobacco or other drug use. Women denied terminations had temporary or sustained reductions in all alcohol measures, but not tobacco or other drugs, suggesting that relationships between pregnancy/parenting and ATOD differ across substances.
Maternal Educational Attainment and Sex Ratio at Birth by Race in the United States, 2007–2015
Victor Grech
Journal of Biosocial Science, forthcoming
Abstract:
Many factors influence the male:female birth ratio (number of male births divided by total births, M/T). Studies have suggested that this ratio may be positively correlated with the education levels of mothers. This study assessed the effect of maternal education on M/T in the US population overall and by racial group. Number of live births by sex of the child, maternal educational level reached and race were obtained from the Centres for Disease Control (CDC Wonder) for the period 2007–2015. The total study sample comprised 28,268,183 live births. Overall, for the four available recorded racial groups (Asian/Pacific Islander, White, American Indian/Alaska Native and Black/African American), M/T rose significantly with increasing education levels (p<0.0001). When analysed by race, this relationship was only found for White births (p<0.0001). The M/T of Black births rose with increasing maternal education level up to associate degree level (p=ns), then fell significantly with higher levels of education (χ 2=4.5, p=0.03). No significant trends were present for Asian/Pacific Islander or American Indian/Alaska Native births. Socioeconomic indicators are generally indicators of better condition and in this study educational attainment was overall found to be positively correlated with M/T, supporting the Trivers–Willard hypothesis.
Hybrid marriages and phenotypic heterosis in offspring: Evidence from China
Chen Zhu et al.
Economics & Human Biology, May 2018, Pages 102-114
Abstract:
In genetics, heterosis refers to the phenomenon that cross-breeding within species leads to offspring that are genetically fitter than their parents and exhibit improved phenotypic characteristics. Based on the theory of heterosis and existing genetic evidence, offspring of “hybrid” marriages (spouses originating from different states/provinces/countries/areas), though relatively rare due to physical boundaries, may exhibit greater genetic fitness in terms of intelligence, height, or physical attractiveness (“distance-performance” hypothesis). This study explores whether heterosis is a contributing factor to offspring’s educational attainment in China by applying a high-dimensional fixed effects (HDFE) modelling framework to the unique 0.1% micro-sample of the 2000 Chinese Population Census data. Concerning potential endogeneity of hybrid marriages, we conduct a series of robustness checks. Reassuringly, the estimated heterosis effect remains significantly positive across various measurements, after controlling for parental educational attainments/height, environmental influences, and over a thousand region and region-by-year fixed effects. The effects in male and higher-educated offspring are found to be stronger. Results are replicated when analyzing body height using data from the China Health and Nutrition Survey. Although endogeneity of “hybrid marriages” may not be completely ruled out, the current study sheds light on the potentially beneficial effects of interprovincial migration on population-level human capital accumulation, and we hope that this paper can intrigue future studies that further address endogeneity. The implied heterosis effect could, therefore, be profound for Homo sapiens as a species from an evolutionary point of view. An additional important implication is that, besides environmental factors, the overall genetic influences of parents on offspring’s performance may be further decomposed into a conventional heredity effect and a heterosis effect that has been neglected previously.
Consanguineous Marriage and the Psychopathology of Progeny: A Population-wide Data Linkage Study
Aideen Maguire, Foteini Tseliou & Dermot O’Reilly
JAMA Psychiatry, forthcoming
Design, Setting, and Participants: This investigation was a retrospective population-wide cohort study of all individuals born in Northern Ireland between January 1, 1971, and December 31, 1986, derived from the Child Health System data set and linked to nationwide administrative data sources on prescription medication and death records. Data from the Child Health System data set identified all 447 452 births delivered to mothers residing in Northern Ireland between 1971 and 1986. The final data set comprised 363 960 individuals, alive and residing in Northern Ireland in 2014, with full data on all variables. The dates of analysis were June 1 to October 31, 2017.
Main Outcomes and Measures: Degree of parental consanguinity was assessed from questions asked of the parents during routine health visitor house calls within 2 weeks of the child’s birth. Potential mental ill health was estimated by receipt of psychotropic medication in 2010 to 2014. Ever or never use was used for the main analysis, with sensitivity analyses using a cutoff of at least 3 months’ prescriptions. Receipt of antidepressant or anxiolytic medications was used as a proxy for common mood disorders, whereas receipt of antipsychotic medications was used as a proxy indicator of psychoses.
Results: Of the 363 960 individuals (52.5% [191 102] male), 609 (0.2%) were born to consanguineous parents. After full adjustment for factors known to be associated with poor mental health, multilevel logistic regression models found that children of first-cousin consanguineous parents were more than 3 times as likely to be in receipt of antidepressant or anxiolytic medications (odds ratio, 3.01; 95% CI, 1.24-7.31) and more than twice as likely to be in receipt of antipsychotic medication (odds ratio, 2.13; 95% CI, 1.29-3.51) compared with children of nonrelated parents.
Why are there more same-sex than opposite-sex dizygotic twins?
Satoshi Kanazawa, Nancy Segal & David de Meza
Human Reproduction, May 2018, Pages 930–934
Study design, size, duration: We analyze two population samples (not subject to Lykken’s rule of two-thirds): the National Child Development Study in the UK (n = 17 419) from 1958 to present, and the National Longitudinal Study of Adolescent Health in the USA (n = 20 745) from 1994 to present.
Main results and the role of chance: The proportion of SS pairs among dizygotic twins was 0.6043 (t(325) = 3.838, P = 0.00015) in the UK and 0.5739 (t(520) = 3.398, P = 0.00073) in the USA.