MPIDR Working Paper

Body mass index during early adulthood and first births: racial/ethnic and sex differences in the US NLSY79 cohort

MPIDR Working Paper WP-2021-012, 51 pages.
Rostock, Max Planck Institute for Demographic Research (June 2021)
Revised April 2022 (Former title: From early life BMI to later life childlessness: consistency across race/ethnicity and mediation by union formation dynamics in the US NLSY79 cohort). The NLSY79 data used for the present study is publicly available via:
Open Access


Growing evidence indicates lifetime fertility is predicted by health conditions during early adulthood such as body mass index (“early BMI”). Less is known if the early BMI to fertility pathway differs by race/ethnicity, a major axis along which disparities in both health and fertility develop. We examined, within each sex, how the deviations of early BMI from healthy range relate to first birth timing and lifetime childlessness in Blacks, Hispanics, and Whites of the US NLSY79 cohort. Obesity was consistently associated with higher childlessness across race/ethnic groups in both sexes, but only in women, its implication in delaying first births manifested after early adulthood. The overall higher childlessness among underweight women was largely driven in Blacks, whereas the lower childlessness among underweight men was detectable in Blacks and Whites. Our findings on the intersectionality of race/ethnicity and sex in the BMI-childlessness pathways encourage more research on the underlying mechanisms.

Keywords: body mass index (BMI), childlessness, first birth, age at first birth, race/ethnicity, Blacks; Hispanics; Whites; United States, NLSY79

Keywords: USA, body weight, completed fertility, desired family size, ethnicity, health, marital union, races, sex differentials
The Max Planck Institute for Demographic Research (MPIDR) in Rostock is one of the leading demographic research centers in the world. It's part of the Max Planck Society, the internationally renowned German research society.