Clomiphene treatment for women with unexplained infertility: placebo-controlled study of hormonal responses and conception rates

Abstract

One hundred and eighteen patients with unexplained infertility were treated with clomiphene (Clomid, Merrell) in a randomized placebo-controlled cross-over study lasting up to 3 months with each preparation. Compared with placebo, clomiphene led overall to a 66% increase in mid-luteal serum progesterone levels (from mean 43 nmol/l to 71 nmol/l, p less than 0.001) and a 53% rise in the 3-month cumulative conception rate (from 14.6% to 22.33%, p less than 0.05). The greatest relative increase in conception rates with clomiphene was in women with infertility lasting more than 3 years (3-month rates from 2.9% to 14.4%, p less than 0.05). Differences in conception rates were not related to the rises in progesterone, and there was no carryover effect of clomiphene into the following placebo cycles in terms of progesterone levels or conceptions. The findings suggest that couples with unexplained infertility of less than 3 years duration are essentially normal, but with more than 3 years duration there is often a subtle disorder of ovulation that is corrected by clomiphene therapy.