We investigated whether sexual activity was associated with reproductive function in the BioCycle Study, a prospective cohort study that followed 259 regularly menstruating women aged 18 to 44years for one (n=9) or two (n=250) menstrual cycles in 2005-2007. Women were not attempting pregnancy nor using hormonal
contraceptives. History of ever having been sexually active was assessed at baseline and frequency of sexual activity, defined as vaginal-penile intercourse, was self-reported daily throughout the study. Serum concentrations of
estradiol,
luteinizing hormone (LH),
follicle-stimulating hormone (FSH),
progesterone, and
testosterone were measured up to 8times/cycle. Sporadic
anovulation was identified using peak
progesterone concentration. Linear mixed models were used to estimate associations between sexual activity and reproductive
hormone concentrations and generalized linear models were used to estimate associations with sporadic
anovulation. Models were adjusted for age, race, body mass index, perceived stress, and alcohol consumption and accounted for repeated measures within women. Elevated concentrations of
estrogen (+14.6%, P<.01), luteal
progesterone (+41.0%, P<.01) and mid-cycle LH (+23.4%, P<.01), but not FSH (P=.33) or
testosterone (P=.37), were observed in sexually active women compared with sexually inactive women (no prior and no study-period sexual activity); sexually active women had lower odds of sporadic
anovulation (adjusted odds ratio=0.34, 95% confidence interval: 0.16-0.73). Among sexually active women, frequency of sexual activity was not associated with
hormones or sporadic
anovulation (all
P>.23). Findings from our study suggest that ever having been sexually active is associated with improved reproductive function, even after controlling for factors such as age.