All About Baby
Revisiting the J-Shape: Human Development and Fertility in the United States
Henrik-Alexander Schubert et al.
Demography, December 2024, Pages 1949-1973
Abstract:
Economic and social development are closely linked with fertility. Several studies have shown that the relationship follows an inverse J-shape: the association is negative at low and intermediate levels of development and reverses to become positive at high development levels. However, more recent research building on subnational and U.S. data found only mixed evidence for the inverse J-shape. In this article, we draw on subnational data on development and fertility in the U.S. states between 1969 and 2018 to examine the relationship between development and fertility. Using a longitudinal approach and addressing several criticisms of the fertility reversal hypothesis, our results support the inverse J-shaped pattern under most model specifications. However, this pattern might have vanished since the 2007-2008 financial crisis. Our findings provide insights into the mechanisms that link development and fertility, showing that gender equality and economic uncertainty mediate the relationship between development and fertility.
The Benefits and Costs of Paid Family Leave
Buyi Wang et al.
NBER Working Paper, December 2024
Abstract:
National paid family leave programs have been repeatedly proposed in the United States in recent years. To inform policy discussions, we provide a benefit-cost analysis of introducing such a program. We systematically identify high-quality, quasi-experimental studies on the impact of paid leave on infants and parents. Using the most conservative estimates or the mean estimates from this literature, we estimate that every $1,000 investment in paid parental leave would generate, respectively, $7,275 or $29,406 in present discounted net social benefits. We use these estimates to conduct a microsimulation of benefits and costs of two policy proposals with different eligibility and wage replacement rates. The first, a 4-week program, would have an initial fiscal cost of under $2 billion and net social benefits of $13 (conservative) or $55 billion (mean). The corresponding figures for the 12-week program are about 3.7 times larger, suggesting that either version would likely generate high returns.
The effect of alimony on married women's labor supply and fertility: Evidence from state-level reforms
Daniel Fernández-Kranz & Jennifer Roff
Journal of Policy Analysis and Management, forthcoming
Abstract:
Reforms that reduce spousal support after divorce are generally thought to reduce the bargaining power of alimony recipients as well as their incentives to participate in the traditional model of household specialization. Using the U.S. Time Use Survey and exploiting a series of recent reforms in several U.S. states that reduced the rights of eligible spouses, we find that wives surprised by the reforms reacted by increasing their labor supply, but the adjustment mechanism varied by educational group. While college educated wives' labor supply increased at the expense of time spent on housework and childcare, wives with less than a college degree sacrificed personal care and leisure time. Effects for men are generally smaller and not statistically significant. We also find a reduction in the rate of new births following the reforms, with the effect being much more pronounced in the case of women with a university education, suggesting that part of the difference in time use may be attributable to differences in preferences and the cost of children by educational levels. Since children are a marital public good, our results imply a decrease in marriage-specific investment. The estimated effects are robust to various sensitivity tests and are greater in couples with a high-income differential and therefore more exposed to changes in alimony laws.
The Causal Effect of Increasing Area-Level Income on Birth Outcomes and Pregnancy-Related Health: Estimates From the Marcellus Shale Boom Economy
Molly Martin, Tiffany Green & Alexander Chapman
Demography, December 2024, Pages 2107-2146
Abstract:
Income is positively correlated with pregnancy health and birth outcomes, but the causal evidence for this association is limited. Leveraging a natural experiment based on the Pennsylvania boom economy created by the extraction of natural gas from the Marcellus Shale geological formation, we test whether area-level income gains impact birth outcomes (birth weight, gestational length, and preterm birth) and pregnancy health (prepregnancy and prenatal smoking, prepregnancy weight status, gestational weight gain, and the timing and adequacy of prenatal care). We append tax data to birth certificate data and compare health outcomes before and after the boom for births occurring in school districts above the Marcellus Shale. We also explore income effects with a subsample of siblings and test for nonlinear income effects by considering preboom district poverty rates. Using instrumented difference-in-differences models, we find that plausibly exogenous income gains increase the likelihood of having adequate prenatal care in the full sample. In the sibling sample, income gains decrease the likelihood of low birth weight but increase the likelihood of prepregnancy underweight among birthing parents. Results are statistically significant in initially high-poverty districts. We thus affirm prior findings of a causal effect of income on birth weight and prenatal care use but find minimal area-level income effects on other pregnancy-related health behaviors and birth outcomes.
The Baby Club: Paternity and Performance in a High-Pressure Setting
David Butler & Robert Butler
Kyklos, forthcoming
Abstract:
We offer new insights into fatherhood by asking if the onset of paternity changes workplace productivity. We do this in the well-monitored and high-pressure setting of professional football using a novel dataset that matches 115 birth disclosures to the performance of 96 players. Our empirical approach involves specifying a performance equation for a suite of match-level performance statistics and estimating OLS and Poisson fixed-effect panel regressions. We find a negative correlation between fatherhood and collaborative performance as measured by expected assists -- a player's ability to create goalscoring opportunities. We also report negative effects for the perinatal period for expected assists and passing measures. There is no evidence of performance changes resulting from expectancy news. As negative performance effects are observed in a context of ‘superstar wages’, this raises concerns for high-pressure labour markets where workers are remunerated less but have low uptake of leave entitlements or where paternity leave is culturally taboo.
Gradual exacerbation of obstetric constraints during hominoid evolution implied by re-evaluation of cephalopelvic fit in chimpanzees
Nicole Webb et al.
Nature Ecology & Evolution, December 2024, Pages 2228–2238
Abstract:
Under the obstetrical dilemma hypothesis, sexual dimorphism in pelvic shape is a solution to accommodate high fetopelvic constraints. It is therefore unclear why chimpanzees display a human-like pattern of pelvic sexual dimorphism despite having easier births enabled by small neonates and capacious pelvic canals. Here we reassessed chimpanzee fetopelvic fit using three-dimensional simulations, revealing a similarly constricted midpelvis as in humans, with even narrower outlet dimensions. Geometric morphometric analyses confirm that female chimpanzees have larger pelvic canals than males despite a smaller body size and a morphology that maximizes pelvic dimensions favourable for parturition, particularly in smaller-bodied individuals. Together with evidence for increased neurological immaturity at birth relative to monkeys, our findings imply substantial obstetric constraints in chimpanzees and possibly other apes. We therefore propose that difficult birth did not arise abruptly in Homo with increasing encephalization but evolved gradually through a series of obstetric compromises from an already constricted birth canal shared across anthropoid primates. Specifically, we propose that obstetric selection pressures exacerbated incrementally with the stiffening of the symphysis that accompanied body size increase in hominoids, while subsequent adaptations to bipedalism shortened the ilium. The resulting contorted birth canal required obligatory fetal rotation, thus greatly increasing birth difficulty.