Unexplained infertility: evaluation of treatment with clomiphene citrate and human chorionic gonadotropin

A double-blind, randomized, prospective therapeutic trial was conducted in 148 couples with unexplained infertility. Treatment consisted of 4 consecutive months of placebo or clomiphene citrate (CC) (100 mg) by mouth on cycle days 5 to 9, and placebo or human chorionic gonadotropin (hCG) (5,000 IU) intramuscularly on cycle days 19, 22, 25, and 28. There were 14 pregnancies during the trial and 39 pregnancies during observation before and after the trial. Placebo treatment resulted in no pregnancies over 4 months. Clomiphene citrate was significantly better than placebo (P less than 0.04), with a pregnancy rate of 19% over the course of 4 months. The pregnancy rate with hCG either alone (11%) or in combination with CC (7.6%), was not significantly better than placebo. Treatment-independent pregnancies, defined as those before treatment (but after enrollment), or more than 1 month after therapy, occurred in 16% of the couples, with a mean time to conception of 8.8 months. As part of their follow-up, 39 of the study couples subsequently underwent in vitro fertilization (IVF), and 43% were found to have a previously unrecognized male factor or fertilization defect. A pregnancy rate of 16% was achieved after a mean of 1.1 cycles in these 39 couples. The authors conclude that CC is useful in treating unexplained infertility and is a reasonable initial therapy. For couples who fail to conceive, IVF may be diagnostic as well as therapeutic.