Luteal oestradiol for patients with serum oestradiol levels lower than expected per oocyte.

Although the efficiency of progesterone in providing luteal phase support has been established, the role of oestradiol supplementation during the luteal phase remains controversial. We evaluated pregnancy outcomes of patients who had a ratio of serum E2 levels on the hCG day to the number of oocytes retrieved (oestradiol/oocyte ratio - EOR) levels of <100 pg/ml by supporting them with additional oestradiol during the luteal phase. In total, 150 patients with an EOR < 100 pg/ml of oestradiol undergoing antagonist intracytoplasmic sperm injection (ICSI) cycles were randomly assigned into two groups to receive either oral oestradiol (4 mg/d) plus vaginal progesterone (90 mg, 2 × 1/day) (group 1) or vaginal progesterone (90 mg, 2 × 1/d) alone (group 2). Implantation rate following transfer of a single embryo did not differ between the two groups (group 1 = 33.3%; group 2 = 34.9%; p = 0.85). Similarly, both groups gave comparable clinical pregnancy rates per embryo transfer with 31.7% in group 1 compared with 28.6% in group 2 (p = 0.69). In conclusion the study suggests that the addition of 4 mg oral E2 to progesterone does not increase the probability of pregnancy.