Male smokers have a decreased success rate for in vitro fertilization and intracytoplasmic sperm injection.

Objective: Smoking by one or both partners can adversely affect IVF outcome. We investigated whether smoking may also play a role in the success rate of intracytoplasmic sperm injection (ICSI), in which initial steps of fertilization are bypassed.

Design: Three hundred one couples (ICSI: 153, IVF: 148) participated in 415 treatment cycles (ICSI: 202, IVF: 213). One hundred thirty-nine men were habitual smokers (ICSI: 71, IVF: 68). Seventy-seven women were smokers (ICSI: 41, IVF: 36). Multiple nominal regression analyses of various steps of assisted reproduction included smoking status, age, semen parameters, and number of embryos transferred.

Settings: Reproductive and andrology unit of the university.

Patient(s): Three hundred one couples seeking fertility treatment.

Intervention(s): Assisted reproduction by in vitro fertilization (IVF) or ICSI.

Main Outcome Measure(s): Clinical pregnancy.

Result(s): Intracytoplasmic sperm injection success (clinical pregnancy) in women with smoking male partners was 22% and was 38% with nonsmoking partners. Similar results were seen for IVF, with 18% vs. 32%. Multinominal logistic regression analysis revealed smoking in men to be a significant predictor of ICSI outcome, along with female age and the number of embryos transferred, whereas clinical pregnancies after IVF were dependent on smoking in men, number of embryos transferred, sperm motility, and female age. Female smoking influenced the number of oocytes retrieved and the fertilization rate of oocytes in IVF but not in ICSI. The odds ratio for failure of ICSI for male smokers in comparison to male nonsmokers was 2.95 (IVF: 2.65).

Conclusion(s): Smoking by males decreases the success rates of assisted reproduction procedures, not only in IVF, but also in ICSI. Apart from putative adverse effects during fertilization, altered DNA in spermatozoa might hamper development of the embryo.