Four RCTs (n=265) were included in the review. Sample sizes ranged from 20 to 106. One trial was double-blind and two were single-blind. All trials except one reported the method of randomisation. One trial reported concealment of allocation.
In comparison with clomiphene citrate, treatment with aromatase inhibitors was associated with significant improvements in pregnancies per patient (OR 2.0, 95% CI 1.1 to 3.8), deliveries per patient (OR 2.4, 95% CI 1.2 to 4.6), deliveries per treatment cycle (OR 2.2, 95% CI 1.2 to 4.1) and pregnancies per treatment cycle (OR 1.8, 95% CI 1.0 to 3.3). No significant heterogeneity was detected for any of the reported outcomes.
Only one miscarriage and one multiple gestation pregnancy were reported; both occurred in clomiphene citrate treatment groups.