Generational differences

Kevin Lewis

March 11, 2018

Is Fertility a Leading Economic Indicator?
Kasey Buckles, Daniel Hungerman & Steven Lugauer
NBER Working Paper, February 2018


Many papers show that aggregate fertility is pro-cyclical over the business cycle. In this paper we do something else: using data on more than 100 million births and focusing on within-year changes in fertility, we show that for recent recessions in the United States, the growth rate for conceptions begins to fall several quarters prior to economic decline. Our findings suggest that fertility behavior is more forward-looking and sensitive to changes in short-run expectations about the economy than previously thought.

Socioeconomic Outcomes of Women Who Receive and Women Who Are Denied Wanted Abortions in the United States
Diana Greene Foster et al.
American Journal of Public Health, March 2018, Pages 407-413

Methods: Women who presented for abortion just before or after the gestational age limit of 30 abortion facilities across the United States between 2008 and 2010 were recruited and followed for 5 years via semiannual telephone interviews. Using mixed effects models, we evaluated socioeconomic outcomes for 813 women by receipt or denial of abortion care.

Results: In analyses that adjusted for the few baseline differences, women denied abortions who gave birth had higher odds of poverty 6 months after denial (adjusted odds ratio [AOR] = 3.77; P < .001) than did women who received abortions; women denied abortions were also more likely to be in poverty for 4 years after denial of abortion. Six months after denial of abortion, women were less likely to be employed full time (AOR = 0.37; P = .001) and were more likely to receive public assistance (AOR = 6.26; P < .001) than were women who obtained abortions, differences that remained significant for 4 years.

Ibuprofen is deleterious for the development of first trimester human fetal ovary ex vivo
Sabrina Leverrier-Penna et al.
Human Reproduction, March 2018, Pages 482–493

Study design, size, duration: Organotypic cultures of human ovaries obtained from 7 to 12 developmental week (DW) fetuses were exposed to ibuprofen at 1–100 μM for 2, 4 or 7 days. For each individual, a control culture (vehicle) was included and compared to its treated counterpart. A total of 185 individual samples were included.

Participants/materials, setting, methods: Ovarian explants were analyzed by flow cytometry, immunohistochemistry and quantitative PCR. Endpoints focused on ovarian cell number, cell death, proliferation and germ cell complement. To analyze the possible range of exposure, ibuprofen was measured in the umbilical cord blood from the women exposed or not to ibuprofen prior to termination of pregnancy.

Main results and the role of chance: Human ovarian explants exposed to 10 and 100 μM ibuprofen showed reduced cell number, less proliferating cells, increased apoptosis and a dramatic loss of germ cell number, regardless of the gestational age of the fetus. Significant effects were observed after 7 days of exposure to 10 μM ibuprofen. At this concentration, apoptosis was observed as early as 2 days of treatment, along with a decrease in M2A-positive germ cell number. These deleterious effects of ibuprofen were not fully rescued after 5 days of drug withdrawal.

Wider implications of the findings: Whereas ibuprofen is currently only contra-indicated after 24 weeks of pregnancy, our results points to a deleterious effect of this drug on first trimester fetal ovaries ex vivo. These findings deserve to be considered in light of the present recommendations about ibuprofen consumption pregnancy, and reveal the urgent need for further investigations on the cellular and molecular mechanisms that underlie the effect of ibuprofen on fetal ovary development.

Racial and Ethnic Variation in the Relationship Between Student Loan Debt and the Transition to First Birth
Stella Min & Miles Taylor
Demography, February 2018, Pages 165-188


The present study employs discrete-time hazard regression models to investigate the relationship between student loan debt and the probability of transitioning to either marital or nonmarital first childbirth using the 1997 National Longitudinal Survey of Youth (NLSY97). Accounting for nonrandom selection into student loans using propensity scores, our study reveals that the effect of student loan debt on the transition to motherhood differs among white, black, and Hispanic women. Hispanic women holding student loans experience significant declines in the probability of transitioning to both marital and nonmarital motherhood, whereas black women with student loans are significantly more likely to transition to any first childbirth. Indebted white women experience only a decrease in the probability of a marital first birth. The results from this study suggest that student loans will likely play a key role in shaping future demographic patterns and behaviors.

Women live longer than men even during severe famines and epidemics
Virginia Zarulli et al.
Proceedings of the National Academy of Sciences, 23 January 2018, Pages E832-E840


Women in almost all modern populations live longer than men. Research to date provides evidence for both biological and social factors influencing this gender gap. Conditions when both men and women experience extremely high levels of mortality risk are unexplored sources of information. We investigate the survival of both sexes in seven populations under extreme conditions from famines, epidemics, and slavery. Women survived better than men: In all populations, they had lower mortality across almost all ages, and, with the exception of one slave population, they lived longer on average than men. Gender differences in infant mortality contributed the most to the gender gap in life expectancy, indicating that newborn girls were able to survive extreme mortality hazards better than newborn boys. Our results confirm the ubiquity of a female survival advantage even when mortality is extraordinarily high. The hypothesis that the survival advantage of women has fundamental biological underpinnings is supported by the fact that under very harsh conditions females survive better than males even at infant ages when behavioral and social differences may be minimal or favor males. Our findings also indicate that the female advantage differs across environments and is modulated by social factors.

Is Fertility After the Demographic Transition Maladaptive?
Rosemary Hopcroft
Journal of Biosocial Science, forthcoming


Fitness is always relative to the fitness of others in the group or breeding population. Even in very low-fertility societies, individual fitness as measured by the share of genes in subsequent generations may still be maximized. Further, sexual selection theory from evolutionary biology suggests that the relationship between status and fertility will differ for males and females. For this reason it is important to examine the relationship between status and fertility separately for males and females–something few demographic studies of fertility do. When male fertility is measured separately, high-status men (as measured by their wealth and personal income) have higher fertility than low-status men, even in very low-fertility societies, so individual males appear to be maximizing their fitness within the constraints posed by a modern society. Thus male fertility cannot be considered maladaptive. When female fertility is measured separately, in both very high- and very low-fertility societies, there is not much variance across women of different statuses in completed fertility. Only in societies currently changing rapidly (with falling fertility rates) is somewhat high variance across women of different statuses in completed fertility found. What is seen across all phases of the demographic transition appears to be a continuation of two somewhat different evolved human reproductive strategies–one male, one female–in changing social and material contexts. Whether contemporary female fertility is maladaptive remains an open question.

Adolescent Pregnancy Prevention Among Youths Living in Group Care Homes: A Cluster Randomized Controlled Trial
Roy Oman et al.
American Journal of Public Health, February 2018, Pages S38-S44

Objectives: To determine if the Power Through Choices (PTC) intervention can increase the use of birth control and reduce pregnancy among system-involved youths living in group care homes.

Methods: We performed a 2-arm cluster randomized controlled trial involving group care homes operated by child welfare or juvenile justice systems in California, Maryland, and Oklahoma with assessments immediately before and after the intervention, and at 6- and 12-month follow-up. We collected data from 2012 to 2014 via self-administered questionnaires. Participants (n = 1036) were young (mean age = 16.1 years), predominantly male (79%), racially/ethnically diverse (37% Hispanic, 20% Black, 21% White, 17% multiracial), and sexually experienced (88%).

Results: At 6-month follow-up, participants in the intervention group had significantly lower odds of having recent sexual intercourse without using birth control (adjusted odds ratio [AOR] = 0.72; 95% confidence interval [CI] = 0.52, 0.98). At 12-month follow-up assessment, participants in the intervention group had significantly lower odds of ever being pregnant or getting someone pregnant (AOR = 0.67; 95% CI = 0.46, 0.99).

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