Pregnancy outcomes when adding a progesterone pessary dose amongst women who are receiving frozen embryo transfer with hormone replacement therapy, compared with placebo.

FETs using HRT stimulation occur with no corpus luteum. This means endometrial growth, maturation and maintenance is entirely dependent on the effect of HRT for at least the first 2-5 weeks post-transfer. By 10 weeks post-transfer the placenta is producing adequate hormone to support the endometrium. Although intramuscular progesterone treatment is popular in North America, in Australia and Europe vaginal preparations are preferred. Natural and HRT FET cycles have been compared and show equivalent live birth rates on meta-analysis. The local experience at Monash IVF is different, with a significantly lower live birth rate for HRT compared to natural FETs (14.5% vs 22.4% - OR 0.59 (0.55-0.62)) for all comers. This difference is maintained when 20 potential confounding factors are allowed for using logistic regression (patient age; number of embryos transferred, embryo maturity etc) with an adjusted odds ratio of 0.55 (0.48-0.64). A recent publication from Yovich (2015) showed a significantly higher live birth rate in women undergoing HRT FETs, where the mid-luteal phase serum progesterone was >50 nmol/L. Review of the Monash IVF dataset investigating serum progesterone concentrations after 14-18 days of treatment in HRT FETs confirmed a significantly higher live birth rate (26.4% vs 11.3%). A shortcoming of measuring progesterone both at mid-luteal and Day 14-18, is that the opportunity to change management and improve outcome has potentially already passed. A further retrospective review of Monash IVF HRT FET cycles investigating progesterone dosage, Day 14-18 serum progesterone and live birth rates, suggested that dose frequency may be as important of actual dosage. This study aims to investigate “at risk” women with low serum progesterone (<50 nmol/L), but measure this after 2 days of treatment and then assess the effect of adding an extra dose of progesterone each day upon the live birth rate.