Impact of smoking and antioxidant use on in vitro fertilization success rates: A retrospective cohort study

Objective: This study investigated the impact of smoking and antioxidant supplementation on in vitro fertilization (IVF) outcomes among couples undergoing IVF treatment at a tertiary infertility center.Methods: This retrospective cohort study included 327 couples who underwent IVF between January 2018 and January 2019. Participants were categorized according to smoking status and antioxidant use before and during treatment. The primary outcome was clinical pregnancy, and secondary outcomes included embryo-related parameters and live birth. Multivariable logistic regression analyses were performed to identify independent predictors of treatment outcomes.Results: Among the study population, smoking was reported by the male partner only in 38.5% of couples, by the female partner only in 8.0%, and by both partners in 21.4% of couples. Pre-treatment antioxidant use was reported by the male partner only in 23.5% of couples, by the female partner only in 6.1%, and by both partners in 6.7% of couples. Smoking status was not significantly associated with clinical pregnancy or live birth in univariate analyses. Male pre-treatment antioxidant use was associated with higher clinical pregnancy and live birth rates in unadjusted analyses; however, this association did not persist after multivariable adjustment. Increasing female age and smoking by both partners were independently associated with reduced odds of live birth, whereas embryological parameters—particularly the total number of embryos formed—were the strongest predictors of treatment success.Conclusion: Smoking by both partners was independently associated with reduced live birth rates, whereas the apparent benefit of male antioxidant supplementation may be influenced by confounding factors. Embryological characteristics remain the primary determinants of IVF success.