Relevance of basal serum FSH to IVF outcome varies with patient age.

Live birth rate (LBR), age and basal serum FSH values were analysed in 1589 women undergoing their first cycle of IVF. Four age groups (<30, 30-34, 35-38, 39-45 years) and three FSH groups (<5, 5-9.9, > or =10 IU/l) were established. Logistic regression analysis was used to determine the effect of age and FSH on live birth. A model to predict the probability of a live birth suggests that an additional 10 years of age reduces the odds for live birth (OR = 0.66, 95% CI 0.48-0.91); an increase of FSH by 5 IU/l reduces the probability of live birth (OR = 0.75, 95% CI 0.61-0.92); women > or =39 years have an additional reduction in probability of live birth (OR = 0.58, 95% CI 0.61-0.92). Analysis by age and FSH categories showed that pregnancy rate (PR) did not change significantly with rising FSH for women <35 years old. In cycles started with serum FSH <5 IU/l, increasing age did not effect PR and LBR. Cycles started with serum FSH > or =10 IU/l had a PR and LBR of 23.6 and 16.9% respectively. The clinical relevance of elevated FSH varies according to age; younger women with elevated FSH and older women with low FSH still have an acceptable LBR.