Oral versus transdermal oestrogen delivery for endometrial preparation before embryo transfer: a prospective, comparative, randomized clinical trial.

Abstract

To determine whether the transdermal route is equal or superior to the oral route, when preparing the endometrium with oestrogens for embryo transfer. Prospective, randomized controlled trial; 140 patients randomized; the pills group followed a protocol with oestradiol valerate pills and the patches group followed a protocol with oestradiol hemihydrate patches. The primary variable was endometrial thickness on day 10 ± 1 of treatment. Secondary variables were endometrial thickness on day 15 ± 1 of treatment, patient satisfaction, plasma levels of oestradiol, rates of pregnancy, miscarriage and delivery. Endometrial thickness was measured on day 10 ± 1 of the cycle, if the lining was 7 mm or less in thickness, another measurement was made on day 15 ± 1. Blood oestradiol levels were analysed on the day the endometrial lining was greater than 7 mm (day 10 ± 1 or day 15 ± 1). Patients completed a survey to evaluate comfort and side-effects. The patches group achieved significantly thicker endometrium by the first check-up on day 10 ± 1 (7.6 mm versus 7.0 mm; P = 0.026), with lower blood levels of oestradiol (159.2 pg/ml versus 237.1 pg/ml; P < 0.001) when the endometrial thickness was over 7mm. The pills group considered the treatment more comfortable, with less side-effects. No significant differences in the rates of pregnancy, miscarriage or live birth were found. Transdermal oestrogen treatment allows patients to reach a higher endometrial thickness after 10 days of treatment, with lower plasma levels of oestradiol, although it is not tolerated as well.