Cumulative pregnancy rates for in vitro fertilization.

Data on 575 couples undergoing 1057 consecutive cycles of in vitro fertilization (IVF) were used to calculate cumulative pregnancy rates for repeated IVF cycles. Excluding preclinical abortions and couples in whom the male partner had poor semen parameters, calculated cumulative pregnancy rates for cycles 1 to 6 were 13.6%, 24.8%, 37.2%, 47.8%, 52.2%, and 59.6%, respectively. A parametric model used to fit these data yielded a strong correlation between observed and predicted pregnancy rates (r = 0.99, P less than 0.001). Predicted cumulative pregnancy rates after 9 and 12 cycles were 75% and 84%, respectively. Excluding preclinical abortions, the pregnancy rate per cycle was approximately constant, at approximately 15% over repeated cycles. As the cost of IVF declines and as treatment cycles become more easily tolerated, persistence in IVF can lead to successful pregnancy for a large proportion of couples.