Spontaneous triggering of ovulation versus HCG administration in patients undergoing IUI

The objective of this prospective randomized study was to assess whether spontaneous triggering of ovulation by detecting LH rise with serial serum testing, results in higher pregnancy rates as compared with administration of human chorionic gonadotrophin (HCG) in patients undergoing intrauterine insemination (IUI) in natural cycles. The trial was registered in clinicaltrials.gov as NCT01414673. Three hundred patients treated by IUI in natural cycles at the Centre of Reproductive Medicine of the Dutch-Speaking Brussels Free University were randomized to either spontaneous triggering of ovulation (spontaneous LH group) (n=150) or administration of HCG (n=150). Donor spermatozoa was used in 197/300 patients (65.67%). The duration of the follicular phase was significantly higher in the spontaneous LH group as compared with the HCG group (P=0.004). However, the ongoing pregnancy rate was significantly higher in the spontaneous LH group as compared with the HCG group (34/150 versus 16/150, P=0.008; difference 12.0%, 95% CI - 3.6 to 20.4). The use of LH for timing ovulation in natural cycles might be the best way to maximize the probability of pregnancy for patients undergoing IUI. It remains unclear whether the probability of pregnancy is associated with the mode of ovulation triggering in intrauterine insemination (IUI) natural cycles. The aim of this study was to assess prospectively whether spontaneous triggering of ovulation by detecting LH rise results in higher pregnancy rates as compared to administration of human chorionic gonadotrophin (HCG) in patients undergoing IUI. Based on our results, spontaneous triggering of ovulation is associated with significantly higher ongoing pregnancy rates compared with administration of HCG in patients undergoing IUI. Therefore, the use of LH for timing ovulation in natural cycles might be the best way to maximize the probability of pregnancy for patients undergoing IUI.