Baby Bumps in the Road: The Impact of Parenthood on Job Performance, Human Capital, and Career Advancement

New mothers’ earnings decrease following birth, while new fathers’ earnings do not. This “child penalty” comes from reductions in employment, hours worked, and wage, but it remains unclear why these outcomes change. We use a matched event study design to study month-level changes to the determinants of wages (job performance, human capital accumulation, and promotions) before, during, and after the transition to parenthood in an environment where employment and hours worked are held constant: the United States Marine Corps. We find mothers’ physical performance, months of job-specific training, and promotion rates decline postbirth, and the effects persist through at least 24 months postbirth. Mothers’ supervisor-rated job performance and scores on a job-specific task (marksmanship) also decline following birth, but recover over time. For fathers, physical performance initially drops but recovers, while other outcomes are largely unchanged. Many civilian occupations (e.g., nursing) are physically demanding. This paper provides insight into why wages may decline for mothers but not fathers, even if a mother remains on the job, working similar hours following birth. JEL Classification: J24, J16, J18, J45