THE EFFECTS OF SMOKING ON OVARIAN-FUNCTION AND FERTILITY DURING ASSISTED REPRODUCTION CYCLES

Objective: To investigate the effects of cigarette smoking on ovarian function and fertility in women undergoing assisted reproduction cycle s. Methods: We assessed the effects of smoking on ovarian function and fertility in a cohort of 499 women. Questionnaires were designed to q uantify past smoking exposure and to determine whether the woman was s moking during the treatment cycle. Ovarian function characteristics an d pregnancy rates were compared among current smokers, past smokers, a nd nonsmokers. Results: Compared with nonsmokers, both current and pas t smokers have reduced gonadotropin-stimulated ovarian function. A his tory of increasing tobacco exposure was associated with decreasing ser um estradiol concentrations, numbers of retrieved oocytes, and numbers of embryos. On average, for every 10 pack-years of cigarette smoking, 2.5 fewer mature oocytes and 2.0 fewer embryos were obtained. Women w ho smoked during their treatment cycle had approximately a 50% reducti on in implantation rate and ongoing pregnancy rate compared with women who had never smoked. Women who quit smoking before their treatment c ycle had the same pregnancy rate as nonsmokers. Conclusion: Cigarette smoking is associated with a prolonged and dose-dependent adverse effe ct on ovarian function. Smoking appears to have a more transient toxic effect on fertility, because current smokers, but not past smokers, h ad a markedly reduced pregnancy rate after treatment cycles compared w ith nonsmokers. Women should quit smoking before assisted reproduction cycles.