The Oral Contraceptive Pill
In an attempt to replace estrogen and minimise bone loss and fracture risk, amenorrheic female athletes and exercising women may be prescribed the oral contraceptive pill (OCP). However, current evidence supporting a role for the OCP in management of exercise-related amenorrhea is inconclusive. Randomised controlled trials (RCT), whereby participants are descriptively matched (e.g. age, training load) before being randomly allocated to receive an intervention or not, are considered the most reliable form of scientific evidence. In the only large RCT conducted to date (N=150), 2 years of OCP therapy in amenorrheic runners resulted in a significant gain of ~1% per year in lumbar spine BMD and whole-body bone mineral content (BMC). However, these amounts were similar to runners who spontaneously resumed menstruating and significantly greater than those for the runners who remained amenorrheic. There was a trend (i.e. not significant) towards a protective effect of OCP therapy on stress fracture risk. However, a major limitation of this study was the high level of non-compliance to treatment by participants. Thus, at this stage it is difficult to draw definitive conclusions regarding the effects of the OCP and other estrogen therapies on BMD in amenorrheic female athletes and exercising women. It must also be noted that hormonal replacement therapy cannot overcome the underlying energy deficit and the direct impact it may have on bone health. In this regard, female athletes and exercising women with menstrual disturbances should increase dietary energy, protein, calcium and vitamin D as a primary step to resume normal menstrual periods and optimise/maintain bone health.
One further consideration is that female athletes and exercising women who are taking the OCP for an extended period of time and are in an energy deficit will not see tangible evidence (i.e. menstrual disturbances) of the deficit. This is because the monthly withdrawal period is artificial (i.e. not due to the woman’s own hormonal status) and the woman can also choose to skip this withdrawal bleed completely by not taking the sugar pills.