Spontaneous LH surges prior to HCG administration in unstimulated-cycle frozen-thawed embryo transfer do not influence pregnancy rates

LH surges are the start of a period of optimal endometrial receptivity. Missing these surges in an unstimulated-cycle frozen-thawed embryo transfer (FET) based on ultrasound alone might lead to incorrect timing of embryo transfer. This prospective, non-randomized trial established the incidence and effect of spontaneous LH surges on ongoing pregnancy rates and assessed the use of ultrasound without LH monitoring in planning FET. All patients undergoing unstimulated-cycle FET in the study centre over a 2-year period were included in this analysis (n = 233). All patients had regular menstrual cycles. Serum LH analysis took place before human chorionic gonadotrophin administration. The main outcome measure was ongoing pregnancy. LH surges occurred in over half of patients. Overall pregnancy rate was 34.3%. Relative risks for ongoing pregnancy for cycles with or without a spontaneous LH surge were not significantly different (ongoing pregnancy rate 33.4% versus 34.8%; RR 1.02, 95% CI 0.7-1.5). Based on these results, it was concluded that LH surges >= 10 IU/l occurred in over 50% of patients, but LH surges demonstrated no significant effect on pregnancy rates. Single LH determination prior to ovulation induction in unstimulated-cycle FET does not seem to have added clinical value. (C) 2011, Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.