Length of Maternity Leave Impact on Child Health Outcomes

Background: The USA is the only developed country lacking a unified policy on paid maternity leave. Longer maternity leave has been associated with decreased preterm birth and infant mortality and increased birthweight; however, these studies have not extended past the neonatal period and their lack of demographic diversity decreases generalizability. The objective of this study was to examine the impact of maternity leave length on infant health during the first year of life.

Methods: This retrospective cohort study used the Military Data Repository (MDR) to identify infants born during periods when active-duty military mothers were granted 6, 12, and 18 weeks of maternity leave. Well-child care, colic, failure to thrive, non-accidental trauma (NAT), and respiratory diagnoses were identified by ICD-9 and -10 codes. Readmission, well-child, and acute care were counted by numbers of admissions and visits. Enrollment data identified child and family demographics. Wilcoxon rank-sum test and Chi2 compared groups; logistic regression analysis determined odds of a particular diagnosis, and Poisson analysis compared rates of well care, acute care, and readmissions. Adjusted models controlled for mother and child demographics and pre-pregnancy mental health diagnosis.

Results: There was a total of 48,916 infants born to active-duty mothers during the study period. 22,472 infants had mothers with 6 weeks of leave, 21,442 infants had mothers with 12 weeks, and 5,002 infants had mothers with 18 weeks (Table 1). In unadjusted and adjusted analyses, as compared to infants of mothers with 6 weeks of leave, infants of mothers with 12 weeks had decreased odds of malnutrition and respiratory conditions, increased odds of NAT and colic diagnosed in the outpatient setting, increased odds of inpatient respiratory admission, and a decreased rate of acute care and readmissions overall. Infants of mothers with 18 weeks of leave had reduced odds of diagnosed malnutrition and respiratory conditions, increased odds of NAT diagnosis in the outpatient setting, and increased well-child and acute care.
Neonatal reflux and inpatient admission for NAT were not significantly different between the three groups (Table 2).

Conclusion: Length of maternity leave was associated with a significant decrease in outpatient malnutrition and respiratory diagnoses, with greater effect seen with longer maternity leave length. NAT and colic were more likely in the groups with longer maternity leave, perhaps related to maternal isolation and stresses as the sole caretaker; this can guide pediatricians’ screening for risk factors. Though overall admissions were less likely in the group with 12 weeks of maternity leave, respiratory admissions were more likely, possibly due to external factors. Finally, increases in well-child visits in the 18-week group indicate that families with longer maternity leave may have better access to well care.