Transdermal testosterone gel vs placebo in women with diminished ovarian reserve prior to in vitro fertilization: a randomized, clinical trial

Diminished ovarian reserve (DOR) is common in women with infertility and is associated with poorer in vitro fertilization (IVF) outcomes. Testosterone is widely used off-label in this patient group, although evidence for its efficacy and safety is limited. To address this, we conducted a triple-blind, placebo-controlled, randomized clinical trial evaluating whether transdermal testosterone gel prior to IVF improves clinical pregnancy rates in women with DOR. Females aged 18-43 with infertility and DOR according to the Bologna criteria were recruited at 10 fertility clinics in Europe between April 2015 and November 2022. Of 316 assessed for eligibility, 290 were enrolled and randomized. Two were excluded from the primary analysis as their treatment coincided with the onset of the COVID-19 pandemic, and they did not start ovarian stimulation, leaving 288 participants. Participants were randomized to 5.5 mg of transdermal testosterone or matching placebo once daily for ~9 weeks prior to ovarian stimulation. All participants received ovarian stimulation in a long GnRH-agonist cycle with 300IU/day of highly purified human menopausal gonadotropin; fresh embryo transfer was performed if an embryo was available. The primary outcome was clinical pregnancy rate following fresh embryo transfer, defined as an intrauterine gestational sac with an embryo demonstrating cardiac activity at ≥7 weeks' gestation. Of the 288 participants, 134 were randomized to testosterone and 154 to placebo. Clinical pregnancy rates did not differ significantly, occurring in 21 women (15.7%) in the testosterone group and 23 (14.9%) in the placebo group (risk ratio (RR), 1.05; 95% confidence interval (CI) 0.61 to 1.81, p = 0.86). The study was terminated for futility at the prespecified interim analysis based on a conditional power calculation once 70% of the target sample size were randomized. In this study, transdermal testosterone did not improve clinical pregnancy rates compared with placebo in patients with infertility and DOR. Trial Registration: ClinicalTrials.gov: NCT02418572, EudraCT: 2014-001835-35.