Luteinizing monitoring in natural cycle for cryopreserved -thawed embryo transfer vs. human chorionic gonadotropin administration: prospective randomized trial

Abstract

OBJECTIVE: To assess whether luteinizing monitoring in natural ovulatory frozen-thawed embryo cycles (FET) cycles improves the pregnancy rates when compared to hCG administration. DESIGN: Prospective randomized trial. MATERIALS AND METHODS: From 1.7.2007 all patients with regular menstrual cycles planned for FER with cleavage stage embryos were randomized to the LH monitoring or hCG group at the outpatient clinic prior to commencing the FET cycle. In the hCG group ovulation was triggered when the dominant follicle was ≥ 17 mm. 5000 IU of HCG was administered and 5 days later ET was carried out. In the LH monitoring group, FET was planned 5 days following the LH surge (the timing of embryo replacement is calculated from the day of ovulation taken as 2 days after the onset of the LH surge. The LH surge was deemed to have begun when the concentration rose 180% above the baseline. No luteal support was given. Ongoing pregnancy was defined as pregnancy developing beyond 7 weeks. Student T test and Fisher's exact test were used for statistical analysis. RESULTS: 137 patients were randomized to LH (n=65) vs. HCG group (n= 72), 35 (25.5%) patients had no embryo transfer due to poor quality of thawed embryos and 102 patients were analysed: 50 patients in the LH group and 52 patients in the hCG group. The mean age of the patients in the LH vs. hCG group (34.9 vs. 34.4 years), body mass index (23.8 vs. 23.4) and mean cycle length (28.7 vs. 28.9 days) were comparable. There were no differences in the mean number of embryos transferred between the groups 1.65 (LH) vs. 1.45 (hCG group), P=NS. In the LH group 20 (40%) patients had 1 embryo transferred vs. 29 (54.7%) in the hCG group (P= NS), 30(60%) of the patients in LH group had 2 embryos transferred compared with 24 (45.3%) in the hCG group (P=NS). On average LH peak was observed after 13.9 days of the cycle while hCG was given after 13.6 days (P=NS). Implantation rates were similar between the two groups 16.0 % in the LH group vs. 12.9% in the hCG group respectively (P=NS) as were the ongoing pregnancy rates as shown in the table.Table 1Pregnancy outcomeLH monitoring n=50(%)hCG administration n=52(%)Positive hCG15 (30)10 (19.2)∗Ongoing pregnancy13 (26)8 (15.4)∗Biochemical2 (4)1 (1.9)Abortion01 (1.9)∗ P=NS. Open table in a new tab ∗ P=NS. CONCLUSIONS: The preliminary results showed that there were no statistically significant differences in the implantation and pregnancy rates in the LH monitoring vs. hCG group in FET natural cycles for cleavage stage embryos.