Effectiveness of Letrozole and Human Chorionic Gonadotropin Injection in Ovulation Induction: A Cohort Study

Abstract

Introduction: Ovulation stimulation followed by timed intercourse or Intrauterine Insemination (IUI) is widely used for treatment of anovulatory infertility. Aim: To compare the effectiveness of Letrozole (LE) alone versus LE and human chorionic gonadotropin injection in ovulation induction and pregnancy rates in women undergoing ovulation induction/follicular tracking in Enugu, Nigeria. Materials and Methods: The longitudinal cohort study was carried out in University of Nigeria Teaching Hospital and Livingston Specialist Gynaecological Hospital in Enugu, Nigeria. Study population were women coming for ovulation stimulation/follicular tracking. Ovulation was confirmed by ultrasound evidence of ovulation with a progesterone level of greater or equal to 25 nmol/L on day 21, positive pregnancy test/ultrasound detection of a gestational sac. Patients were consecutively assigned to group A or B. Group A received LE only for the induction while group B received 10000 IU of human chorionic gonadotropin injection in addition to LE. A total of 5 mg of LE was given daily from day 3 to day 7. The primary outcome measured was the number of ruptured/crenated follicles on either arm while the secondary outcomes were the number of Luteinised Unruptured Follicles (LUF) and pregnancy rates. The Statistical analysis was performed using the Statistical Package for the Social Sciences version 21.0 software (SPSS Inc., Chicago, IL, United States). Results: A total of 50 women were in each arm of the study. There was no significant difference in age and parity between the two arms. There was no significance difference between the period of infertility and the number of the previous cycles of ovulation stimulation. (p=0.444 and 0.526, respectively). Ovulation was significantly associated with HCG injection (p=0.001). However, there was no statistical significance between both arms regarding the number of LUF (p=0.216). HCG injection was significantly associated with pregnancy. Subjects who took HCG injection were over two times more likely to become pregnant than those without HCG injection (OR=2.488, 95% CI for OR=1.057-5.857, p=0.037). Conclusion: This study showed that both the ovulation rate and pregnancy rate are significantly improved when human chorionic gonadotrophin injection is given after ovarian stimulation.