Effect of Serial Pregnancies on Physical Fitness

Pregnancy has a profound impact on physical fitness, and delivery does not allow for rapid return to peak performance levels as physiologic changes can persist for greater than 1 year postpartum. Multiple studies across all military services have documented decrements in physical performance with pregnancy among women. The purpose of this study was to determine the impact of serial pregnancies on physical fitness and body composition in a cohort of Army women. We hypothesized that a second pregnancy would be associated with increasing decrements in physical fitness in active duty soldiers beyond that seen following a first delivery.

This retrospective cohort study screened all active duty soldiers who had delivered a singleton pregnancy of ≥32 weeks gestation between January 1, 2011 and March 31, 2017 at a single military medical center. This roster of eligible women was used to extract Army Physical Fitness Test (APFT) and height/weight data from the U.S. Army Digital Training Management System. Soldiers who delivered their first 2 pregnancies over this period were included. Select antepartum, intrapartum, and postpartum data were collected from the electronic medical record. The primary outcome variables were raw scores for push-ups, sit-ups, and run events as well as weight measures across the 2 pregnancies. The secondary outcomes were the failure rates on both the APFT events and body mass index measurements. Data were analyzed using paired t-tests to compare the means of APFT scores across the 2 pregnancies. The subjects served as their own controls. This study was approved by Regional Health Command-Pacific.

A total of 2,103 active duty soldiers delivered singleton pregnancies at Tripler Army Medical Center between January 2011 and March 2017. Among these, 16 women delivered both their first- and second-term pregnancies and had APFT data available for analysis. Average age at time of first and second delivery was 26.1 and 28.1 years, respectively. Mean time separating the first postpartum APFT from the delivery was 8.8 months for the first pregnancy and 7.3 months following the second.A significant decrease in mean sit-up score was found comparing APFT-1 with APFT-2 (72.1 vs 65.7, P = .043) and comparing APFT-1 to APFT-3 (72.1 vs 60.9, P = .002). A significant increase in mean run time was found comparing APFT-1 to APFT-3 (16.9 minutes vs 17.9 minutes, P = .010) and APFT-2 to APFT-3 (17.5 minutes vs 17.9 minutes, P = .027). Comparing APFT-1 to APFT-3 showed a significant decrease in sit-up raw scores (P = .002), run times (P = .010), and total APFT scores (P = .01). Overall, the data show a trend of decreasing performance in all APFT events across the 3 APFTs and a trend toward higher failure rates. This cohort of soldiers did not experience weight gain following the pregnancies.

The present study is the first to analyze the association of serial pregnancies on physical fitness utilizing a validated physical fitness test, and the results suggest that a second pregnancy is associated with progressive worsening of performance. This study is limited by the small sample size, and future studies could further elucidate the degree to which serial pregnancies affect physical fitness.