Asymmetric patterns in early parent–infant nighttime care: Persistence of maternal involvement during father leave periods.

How do first-time fathers and mothers share the care of their new infant at night? Using smartphone-based experience sampling, we compared parental reports during maternity and paternity leave. During maternity leave, mothers reported engaging in 2.70 more nighttime care events than fathers, performing approximately 77% of the nighttime checking or responding to infants. During paternity leave, fathers' reported share of nighttime care increased by about 17%, while mothers reported that their share decreased by 14%. However, mothers checked on their infants on average 1.43 times more than fathers during paternity leave. The total number of nighttime checks was similar between the maternity and paternity leave periods, despite infants being older during paternity leave, when sleep patterns typically stabilize. We also found considerable discrepancies between partners' reports: both parents consistently reported their partners doing less nighttime care than the partners reported themselves. The discrepancy was particularly pronounced in mothers' evaluations of father involvement during maternity leave. These findings reveal persistent asymmetries in parental nighttime care, even when fathers are on paternity leave. We suggest that the distribution of nighttime care, therefore, is not solely driven by parental leave status but might reflect established infant care routines, social norms, and other biological factors. These findings have implications for understanding the development of co-parenting dynamics and informing policies aimed at promoting father involvement in early infant care. (PsycInfo Database Record (c) 2025 APA, all rights reserved).