Determinants of ovarian function in young women

The female reproductive system is sensitive to its environment, and ovarian function is often suppressed when confronted with a stressor. But while such an effect is well documented for energetic stresses such as low dietary intake, high physical activity or both, the evidence in support of a direct effect of psychological stress on ovarian function is inconclusive.; In addition to looking at psychological and energetic variables, this project also looked into other factors that have been previously found to correlate with reproductive hormone levels. The project had two phases. Phase 1 was a large-scale survey study in which over 300 women filled out lengthy questionnaires about their menstrual cycle length and regularity and their usual levels of physical activity, dietary intake, and psychological stress. Phase 1 also served as a recruitment vehicle for Phase 2, which was a more in-depth study of ovarian function variation in college-age women.; The results of Phase 1 showed that body mass index, exercise levels, energy balance, cognitive dietary restraint, perceived psychological stress and age of menarche were all associated with menstrual cycle variables.; In Phase 2, subjects collected daily saliva samples over a menstrual cycle from which estradiol and progesterone were measured. Cortisol and urinary c-peptide were also measured in an attempt to tease apart the metabolic mechanisms that could underlie the effects of different types of stress on ovarian function. The overall level of suppression of ovarian function in phase 2 subjects was high with only 43% of subjects showing evidence of ovulation. Earlier age of menarche, more hours spent sleeping and low levels of dietary restraint were associated with higher levels of ovarian function. Other variables predicted to explain variance in ovarian function including exercise, psychological stress, c-peptide and cortisol were unrelated to reproductive hormones. Possible explanations for these findings include the young age of the subjects and the variation present in the measures.