Effect of Pregnancy on Performance of a Standardized Physical Fitness Test

Research has demonstrated the positive effects of exercise during pregnancy on maternal and fetal outcomes, but very little research has evaluated the effect of pregnancy on women's fitness or the length of time needed to recover prepregnancy fitness after delivery. These questions are important in providing anticipatory guidance to women, from elite athletes to women who just want to know how their bodies will change after pregnancy. To women in the military, postpartum fitness is critically important because failing the mandatory biannual physical fitness assessment (PFA) can severely damage or prematurely end a woman's career. Therefore, understanding the expected changes in fitness, the timeline required to regain prepregnancy fitness levels after delivery, and understanding risk factors for physical fitness testing failure is an important aspect of obstetrical care in military populations. The Navy PFA is a unique opportunity to measure the effect of pregnancy on women's ability to perform a standardized fitness assessment. The objective of this research is to use data from the Navy PFA to compare fitness levels in individual women before and after pregnancy, and to identify individuals at risk for poor fitness levels and Physical Readiness Test (PRT) failure postpartum.

A cohort of pregnant sailors stationed at Naval Medical Center San Diego in 2013 and 2014 was identified from Physical Readiness Information Management System. PFA results before pregnancy (PRE) were compared with results from the first postpartum PFA cycle (PP1) and second postpartum cycle (PP2). To evaluate risk factors for poor postpartum fitness levels, a nested case control was created including women who failed PP1 compared with women who passed.

142 women were included in the cohort study and 99 women were included in the case control portion. Muscular strength was reduced postpartum; the mean number of sit-ups was 73.4 and 67.1 (p ≤ 0.001) and the mean number of push-ups was 38.5 and 35.2 (p = 0.002) prepregnancy and postpartum, respectively. Sixteen women failed PP1 compared with 5 women failing before pregnancy; odds ratio (OR) 3.2 (1.3, 10.5). Women who failed PP1 were significantly older compared with women who passed PP1, mean age 31.4 and 27.3 (p = 0.02); respectively. Significantly more women failing PP1 had a diagnosis of gestational diabetes OR 5.4 (1.1, 27.4) and anemia in pregnancy OR 11.9 (1.2, 164.5).

At 6 months postpartum, active duty women have decreased muscular and cardiovascular fitness, and have not yet regained prepregnancy weight. These changes put women at high risk for failing the PFA. These changes resolve by the second postpartum PFA. Women above the age of 30 and those who develop gestational diabetes or anemia during pregnancy are at risk for poor postpartum fitness. The Navy should consider extending the time allowed for women to meet PFA standards postpartum and develop a program to monitor women's progress toward PFA standards and provide assistance as needed.