Discrimination between chronological and ovarian age in infertile women aged 35 years and older: predicting pregnancy using basal follicle stimulating hormone, age and number of ovulation induction/intra-uterine insemination cycles.

A marked decline in fertility rates has been demonstrated in women > 35 years of age. We have previously demonstrated the importance of basal follicle stimulating hormone (FSH) concentrations plus chronological age to predict pregnancies in women aged >/=40 years undergoing ovulation induction therapy. The purpose of the current study was to extend our previous study and determine the impact of age, basal FSH concentrations and ovulation induction/inter-uterine insemination (IUI) treatment cycles on pregnancy rates in infertile women age >/=35 years. This prospective observational study was performed at a tertiary university fertility centre. Assessments of basal hormonal status and ovulation induction protocols were performed. The main outcome measured was clinical pregnancies. A total of 770 treatment cycles in 179 women aged >/=35 years were analysed. The impact of basal FSH concentrations on treatment outcomes could be bifurcated into a favourable group (FSH </=23 mIU/ml) and a poor prognosis group (FSH >/= mIU/ml). A multivariate logistic regression model was generated which accurately predicted pregnancies. There was a high degree of correlation between predicted pregnancies and observed pregnancies (r = 0.86). We conclude that age, number of treatment cycles and the interaction term basal FSH x age are useful and significant predictors of pregnancies in patients aged >/=35 years undergoing ovulation induction/IUI therapy.