A Cochrane review included 28 studies on oral anti-oestrogen agents for ovulation induction, with a total of 3 377 subjects. 5 studies reported live birth/ongoing pregnancy as an outcome. Miscarriage, multiple pregnancy rates, and adverse events were poorly reported.
Clomiphene was effective in increasing pregnancy rate compared to placebo (OR 5.8, 95% CI 1.6 to 21.5; 3 studies, n=133) as was clomiphene plus dexamethasone treatment (OR 6.20, 95% CI 2.20 to 17.48; 4 trials, n=434) compared to clomiphene alone. No evidence of a difference in effect was found between clomiphene versus tamoxifen or clomiphene in conjunction with human chorionic gonadotrophin (hCG) versus clomiphene alone.
The remaining results had only one study in each comparison. A significant improvement in the pregnancy rate was reported for clomiphene plus combined oral contraceptives versus clomiphene alone (OR 27.18, 95% CI 3.14 to 235.02; 1 study, n= 51). No evidence of a difference in effect on pregnancy rate was found with any of the other comparisons.