Menstrual disturbances in British Servicewomen: A cross-sectional observational study of prevalence and risk factors

Abstract

Female athletes are at increased risk of menstrual disturbances. The prevalence of menstrual disturbances in British Servicewomen and the associated risk factors is unknown. All women under 45 years in the UK Armed Forces were invited to complete a survey about demographics, menstrual function, eating and exercise behaviors, and psychological well-being. 3,022 women participated; 18% had oligomenorrhoea or amenorrhoea in the last 12 months, 25% had a history of amenorrhoea, and 14% had delayed menarche. Women who sleep ≥ 8 h were at a lower risk of a history of amenorrhoea than women who sleep ≤ 5 h [odds ratio (95% confidence intervals) = 0.65 (0.48, 0.89), p = 0.006]. Women who completed > 10 days of field exercise in the last 12 months were at higher risk of a history of amenorrhoea than women completing no field exercise [1.45 (1.13, 1.85), p = 0.004]. Women at high risk of an eating disorder (FAST score >94) were at higher risk of oligomenorrhoea or amenorrhoea [1.97 (1.26, 3.04), p = 0.002] and history of amenorrhoea [2.14 (1.63, 2.79), p < 0.001]. Women with symptoms of anxiety or depression were at higher risk of a history of amenorrhoea [1.46 (1.20, 1.77) and 1.48 (1.22, 1.79), p < 0.001]. British Servicewomen had a similar prevalence of menstrual disturbances to some endurance athletes. Eating disorders, sleep behaviors, and management of mental health, provide targets for protecting health of the reproductive axis.

Menstrual Function, Eating Disorders, Low Energy Availability, and Musculoskeletal Injuries in British Servicewomen

“…Finally, menstrual disturbances can be caused by low energy availability, but low energy availability can disturb bone metabolism (41) and bone morphology (42) independent of menstrual function. Therefore, the association between menstrual disturbances and the risk of injury in female athletes could be also due to the direct endocrine (nonreproductive) effects of low energy availability, whereas menstrual disturbances in servicewomen can be caused by factors other than low energy availability, including psychological stress and poor sleep (13). Conversely, we cannot rule out a role of menstrual disturbances contributing to increase the risk of injury in our data as i) we corrected our α for the number of models ( P ≤ 0.006), and there were associations between oligomenorrhea and/or amenorrhea and history of amenorrhea and a time-loss injuries in the last 12 months at the uncorrected α ( P < 0.05); ii) our measure of menstrual function was number of periods, and there may be subclinical disturbances not captured by these methods that contribute to increased injury risk; and iii) we demonstrated the associations between LEAF-Q score and injury risk, and the LEAF-Q score is partly dependent on menstrual function.…”

“…A menstrual disturbance would be expected to precede an injury, and we may have lacked the time resolution in our measures to identify this relationship. Also, menstrual disturbances in servicewomen may increase the risk of leaving the military—possibly because of increased risk of injury—and our data could be a “survivor” cohort of those who develop a menstrual disturbance without increased injury risk (13). Finally, menstrual disturbances can be caused by low energy availability, but low energy availability can disturb bone metabolism (41) and bone morphology (42) independent of menstrual function.…”

“…Statistical analyses. The primary outcome of this study was the prevalence of oligomenorrhea or amenorrhea (13). Sample size was calculated using the formula…”

“…The primary outcome of this study was the prevalence of oligomenorrhea or amenorrhea (13). Sample size was calculated using the formula Z 1− α /2 2 p (1 − p )/ d 2 , where Z 1− α /2 is 1.96 for 5% type 1 error, p is the estimated population prevalence, and d is the marginal error.…”

“…Many military roles are physically and psychologically demanding; energy intake may not always match high total energy expenditures and servicewomen may be at risk of Triad/RED-S outcomes (12). We have previously reported in British servicewomen a high prevalence of oligomenorrhea or amenorrhea (18%) and eating disorders (13%) (13). Servicewomen are also at high risk of bone stress injuries and other musculoskeletal injuries (14), but whether markers of the Triad/RED-S, including menstrual disturbances, eating disorders, and low energy availability, are associated with bone stress injuries and other musculoskeletal injuries in British servicewomen is unknown.…”