<i>In vitro</i> fertilization outcomes in young women and their association with male and female infertility aetiology

Infertility aetiology has been shown to be related to reproductive outcomes in the wide reproductive age range. The aim of this study was to examine young women <i>in vitro</i> fertilization (IVF) cycle outcomes according to age and infertility cause. This retrospective cohort study was comprised of 305 couples with a female partner aged 17-25 years with either male or female infertility that underwent a fresh IVF cycle between 2003 and 2020. Comparison according to age groups 17-22 years (<i>n</i> = 117) and 23-25 years (<i>n</i> = 188) showed similar outcomes, except for higher rates of 3 pronuclei (PN) embryos in the younger group. However, allocation to groups by infertility aetiology - male factor (MF) (<i>n</i> = 241) vs. female factor (FF) (<i>n</i> = 64) demonstrated lower fertilization rate in the FF vs. MF group (58% vs. 63%, <i>p</i> = 0.049) and higher percent of 1PN and 3PN embryos (0.7% vs. 0.2% and 0.7% vs. 0.1%, <i>p</i> < 0.001 for both). Chemical pregnancy and live-birth rate were significantly higher in the MF vs. FF group (48.9% vs. 29.5%, <i>p</i> = 0.02 and 41.9% vs. 11.0%, <i>p</i> = 0.038). The only parameter associated with live birth rate in a logistic regression analysis was male infertility aetiology (<i>OR</i> = 2.17, <i>p</i> = 0.038). Young couples undergoing IVF cycles due to female factor infertility have poorer reproductive outcomes compared to male factor-related infertility and higher rates of 1PN and 3PN embryos.