Postpartum Fitness and Body Mass Index Changes in Active Duty Navy Women.

Introduction: Active duty Navy women participate in biannual Physical Fitness Assessments (PFAs), which include height and weight measurements and a Physical Readiness Test (PRT). PFAs are waived during pregnancy and resume the cycle after 6 months following maternity leave. The purpose of this study was to compare changes in PFA results over time between women who had or did not have a live birth during the follow-up period, and identify characteristics of women with lower PFA results postpartum.

Materials And Methods: This longitudinal study included 14,142 active duty Navy women, aged 19-40 years, with PFA results during July 2011-June 2015. Multivariable logistic regression, Stuart-Maxwell tests, and mixed effects modeling were used to examine changes in PRT scores and body mass index over time between women with and without a live birth during follow-up. All data were analyzed in 2017. This study was approved by the institutional review boards at the Uniformed Services University Office of Research and the Naval Health Research Center, and informed consent was waived in accordance with 32 CFR § 219.116(d).

Results: Postpartum women had increased odds of PRT failures (AOR = 3.88, 95% CI: 1.44-10.40) and lower PRT scores (AOR = 1.47, 95% CI: 1.12-1.92) up to 2.5 years postpartum, versus women without a live birth. Being enlisted, obese/overweight prepregnancy, and younger were risk factors for suboptimal PFA outcomes. Mean core strength and cardiovascular endurance, but not upper body strength, scores were significantly lower in postpartum women at 1 year postpartum versus women without a live birth.

Conclusions: Our findings show that additional interventions may be needed to assist women in returning to prepregnancy fitness up to 1 year postpartum. Future studies should examine additional factors that may improve postpartum fitness in addition to enhancing maternity leave policies.