Planned conventional fertilization compared to intracytoplasmic sperm injection improves pregnancy rates in patients with unexpalined infertilty

Abstract

While intracytoplasic sperm injection (ICSI) reduces the rare event of failed fertilization among couples with unexplained infertility, it is unclear as to whether it improves fertilization and pregnancy rates compared to conventional fertilization. To compare the fertilization, implantation, and pregnancy rates following ICSI versus conventional insemination in couples with unexplained infertility. This was a retrospective cohort study of women with a diagnosis of unexplained infertility undergoing autologous in vitro fertilization (IVF) with an antagonist. The cohort included 3,281 fresh antagonist IVF cycles performed between January 1, 2013 and December 31, 2015 at 14 clinics in the IntegraMed Fertility Network. Fertilization method was determined from the treatment plan. Fertilization, implantation, and pregnancy rates were compared using Student T-test an Chi-square analysis where appropriate Subsequent binomial regression models were constructed to determine the probability of ultrasound confirmed pregnancy adjusting for age, nulligravidity, history of prior IVF, race (White: yes/no), and using a cluster term for each clinic. Women prescribed ICSI (N=1879) tended to be older (34.8 ± 3.85 years versus 34.3 ± 3.78), were more likely to be white (68% versus 61%), were less likely to be nulligravid (46% versus 50%), and more likely to have done a prior IVF cycle (39% versus 26%) compared to women prescribed conventional fertilization. The fertilization, implantation and pregnancy rates for ICSI fertilization was significantly lower when compared to conventional fertilization (Table 1). Compared to conventional insemination, ICSI reduced the probability of pregnancy by 10% (relative risk [RR] 0.90 [95% CI 0.82 – 0.99]) in unadjusted and adjusted models (RR 0.91 [95% CI 0.83 – 0.99]). For patients with unexplained Infertility undergoing an antagonist IVF cycle, ICSI significantly reduces fertilization, pregnancy, and implantation rates compared to conventional fertilization.