The Risk of Menstrual Dysfunction Increases for Women during U.S. Army Basic Combat Training

To determine whether changes in menstruation develop in female trainees during BCT and whether changes in body mass, body composition and/or physical activity are associated with menstrual interruption during BCT.

Female trainees grouped according to self-reported menstrual status in the 12 months before BCT as having regular cycles (RC; n = 352) or MD ( n = 97) completed height, body mass, and body composition assessments and questionnaires before and after BCT. Fisher's exact test and Mann-Whitney U test were used to compare between-group differences in categorical and continuous variables, respectively. Among RC trainees, odds ratios were calculated to examine the influence of changes in body mass, lean mass, and fat mass on a trainee's likelihood to miss a period during BCT.

There were no differences in race, height, body mass, body mass index, or physical activity history at pre-BCT between RC and MD ( P > 0.05). Overall, 86% of trainees experienced changes to menstruation during BCT. RC were more likely than MD to have at least one period during BCT (81% vs 69%, respectively, P = 0.01). Among RC, gaining more body mass and lean mass and losing less fat mass were associated with increased odds of missing a period during BCT.

These findings demonstrate that most female trainees experience menstrual changes during BCT. Menstrual cycle interruptions do not appear to align with loss of body or fat mass.