Conceivable
Human Sexual Cycles are Driven by Culture and Match Collective Moods
Ian Wood et al.
Scientific Reports, December 2017
Abstract:
Human reproduction does not happen uniformly throughout the year and what drives human sexual cycles is a long-standing question. The literature is mixed with respect to whether biological or cultural factors best explain these cycles. The biological hypothesis proposes that human reproductive cycles are an adaptation to the seasonal (hemisphere-dependent) cycles, while the cultural hypothesis proposes that conception dates vary mostly due to cultural factors, such as holidays. However, for many countries, common records used to investigate these hypotheses are incomplete or unavailable, biasing existing analysis towards Northern Hemisphere Christian countries. Here we show that interest in sex peaks sharply online during major cultural and religious celebrations, regardless of hemisphere location. This online interest, when shifted by nine months, corresponds to documented human births, even after adjusting for numerous factors such as language and amount of free time due to holidays. We further show that mood, measured independently on Twitter, contains distinct collective emotions associated with those cultural celebrations. Our results provide converging evidence that the cyclic sexual and reproductive behavior of human populations is mostly driven by culture and that this interest in sex is associated with specific emotions, characteristic of major cultural and religious celebrations.
Maternal age at birth and daughters’ subsequent childlessness
Olga Basso et al.
Human Reproduction, February 2018, Pages 311–319
Study design size and duration: This analysis included 43 135 women from the US-based Sister Study, a cohort study of 50 884 sisters of women with breast cancer recruited between 2003 and 2009.
Participants/materials, setting, methods: Participants had no breast cancer at baseline. Women were included in the analytic sample if they were born between 1930 and 1964 and were at least 44 years old at enrolment. Median age when reproductive history was last ascertained was 63.8 years. We estimated relative risks (RR) and 95% CI of lifelong childlessness as a function of maternal age at birth, using multivariable log-binomial models, including total number of siblings, birth order, socioeconomic indicators of the family of origin, race and birth cohort. We examined the association in different subgroups and in a sibling-matched analysis including 802 sister pairs discordant for childlessness.
Main results and role of chance: Compared with women born to 20–24-year-old mothers, those born to mothers aged 25–29, 30–34 and ≥35 years were more likely to be childless [RR (95% CI): 1.21 (1.14–1.29), 1.30 (1.22–1.39) and 1.40 (1.31–1.50), respectively]. The association was consistent in strata defined by birth cohort, number of siblings, birth order, and participant’s educational level, as well as within sister pairs. Overall, we found weak evidence for an independent contribution of paternal age at birth to the daughter’s probability of childlessness.
The Impact of a Parental Notification Requirement on Illinois Minors' Access to and Decision-Making Around Abortion
Lauren Ralph et al.
Journal of Adolescent Health, forthcoming
Methods: We analyzed administrative and medical records of 1,577 women obtaining an abortion before and after implementation of a PN requirement at one Illinois facility. Using multivariate regression within a difference-in-differences framework, we quantified changes in the number and timing of women seeking care, frequency of parental awareness and support, travel from out-of-state, decision certainty, and anticipated coping among minors 17 years and below compared with young adults (YAs) aged 18–20 years.
Results: A smaller proportion of abortions to women ages 20 years and under post-law were among minors (39%–33%, p = .017). Compared with YAs, minors experienced a larger increase in parental awareness (71%–93% [minors] vs. 53%–58% [YAs], p < .000]; however, parents' support for the decision was unchanged. The proportion of minors certain of their decision went from 77% pre-law to 71% post-law (p = .099) compared with 82% pre- and post-law among YAs (p = .798). Compared with YAs, a larger proportion of minors obtained second trimester care post-law if coming from another state (21%–31% [minors] vs. 23%–16% [YAs], p = .022).
Conclusions: Illinois' PN requirement was associated with a decrease in the number of abortions among minors, delayed care for those from out-of-state, increased parental awareness of the pregnancy, and no change in parents' support.
Assisted Reproductive Technology with Donor Sperm: National Trends and Perinatal Outcomes
Sabrina Gerkowicz et al.
American Journal of Obstetrics and Gynecology, forthcoming
Study Design: Retrospective cohort study using data from all United States fertility centers reporting to the Centers for Disease Control and Prevention’s National Assisted Reproductive Technology Surveillance System, accounting for ∼98% of assisted reproductive technology cycles (definition excludes intrauterine insemination). The number and percentage of assisted reproductive technology cycles using donor sperm and rates of pregnancy, live birth, preterm birth (<37 weeks), and low birth weight (<2500g) were the primary outcomes measured. Treatments assessed include use of donor versus non-donor sperm. The trends analysis included all banking and fresh assisted reproductive technology cycles using donor and autologous oocytes performed between 1996 and 2014 (n=1,710,034). The outcomes analysis was restricted to include only fresh autologous cycles performed between 2010 and 2014 (n=437,569) in order to focus on cycles with a potential outcome and cycles reflective of current practice, thereby improving the clinical relevance. Cycles cancelled prior to retrieval were excluded. Statistical analysis included linear regression to explore polynomial trends and log-binomial regression to estimate relative risk for outcomes among cycles using donor and non-donor sperm.
Results: Of all banking and fresh donor and autologous oocyte assisted reproductive technology cycles performed between 1996 and 2014, 74,892 (4.4%) used donor sperm. In 2014, 7,351 assisted reproductive technology cycles using donor sperm were performed, as compared to 1,763 in 1996 (6.2% vs. 3.8% of all cycles). Among all autologous oocyte cycles performed between 2010 and 2014, the live birth rate was lower for donor sperm (27.9%) than non-donor sperm cycles (32.5%); however, after adjustment for maternal age, donor sperm use was associated with an increased likelihood of live birth (adjusted relative risk=1.06, 95% confidence interval=1.01-1.10). Per transfer, there was no significant difference in live birth rates for donor versus non-donor sperm (31.9% vs. 36.8%; adjusted relative risk =1.04, 95% confidence interval =0.998-1.09). Per singleton live birth there was no significant difference in preterm birth (11.5% vs. 11.8%; adjusted relative risk =0.98, 95% confidence interval =0.90-1.06); however, low birth weight delivery was slightly lower in donor sperm cycles (8.8% vs. 9.4%; adjusted relative risk =0.91, 95% confidence interval =0.83-0.99).
Conclusions: Donor sperm use in assisted reproductive technology has increased in the United States, accounting for approximately 6% of all assisted reproductive technology cycles in 2014. Assisted reproductive technology treatment and perinatal outcomes were clinically similar in donor and non-donor sperm cycles.
Deployment and Preterm Birth Among United States Army Soldiers
Jonathan Shaw et al.
American Journal of Epidemiology, forthcoming
Abstract:
With increasing integration of women into combat roles in the United States military, it is critical to determine whether deployment, which entails unique stressors and exposures, is associated with adverse reproductive outcomes. Few studies have examined if deployment increases the risk of preterm birth; no studies have examined a recent cohort of servicewomen. We therefore used linked medical and administrative data from the Stanford Military Data Repository for all United States Army soldiers with deliveries between 2011–2014 to estimate the associations between prior deployment, recency of deployment, posttraumatic stress disorder and spontaneous preterm birth, adjusting for socio-demographic, military-service, and health-related factors. Of 12,877 deliveries, 6.1% were spontaneous preterm births. The prevalence was doubled (11.7%) among soldiers who delivered within 6 months of return from deployment. Multivariable discrete-time logistic regression models indicated that delivering within 6 months of return from deployment was strongly associated with spontaneous preterm birth (adjusted odds ratio = 2.1, 95% confidence interval: 1.5, 2.9). Neither multiple past deployments nor posttraumatic stress disorder were significantly associated with spontaneous preterm birth. Within this cohort, timing of pregnancy in relation to deployment is identified as a novel risk factor. Increased focus on servicewomen's pregnancy timing and pre-deployment access to reproductive counseling and effective contraception is warranted.
A Structural Explanation of Recent Changes in Life-Cycle Labor Supply and Fertility Behavior of Married Women in the United States
Seonyoung Park
European Economic Review, February 2018, Pages 129-168
Abstract:
This study documents and explains important changes in the life-cycle labor supply and fertility behavior of married women in the United States from the 1950s to more recent cohorts. The younger cohorts, relative to the 1950s, supply more labor at earlier stages of the life-cycle, delay motherhood to later stages without reducing the fertility rate, and upon childbearing, show a greater tendency to stay out of the labor force. In a life-cycle model for married couples in which a household makes decisions on fertility as well as labor supply, consumption, and savings, all the behavioral changes are jointly and quantitatively explained by a combination of changes in various labor supply/fertility determinants, with the increased returns (penalties) to work (non-work) experience being the dominant contributor. The results survive a series of robustness tests, including endogenizing education choice and assortative marriage.