The effects of smoking on fertility from gametogenesis to implantation

Abstract

The literature concerning the effects of cigarette smoking, treatment with nicotine, cigarette smoke condensates, or cigarette smoke constituents on reproductive events from gametogenesis to implanatation is reviewed. Epidemiologic evidence, although scanty, suggests that cigarette smoking decreases fertility in women. Cigarette smoking is also associated with an increased frequency of menstrual abnormalities and a cigarette dose-related decrease in the age of spontaneous menopause. Similar epidemiologic studies assessing reproductive function have not been conducted among men who smoke. Several small studies have demonstrated decreased sperm counts and an increased frequency of abnormal sperm morphology among male smokers. Cessation of smoking in several of these studies has been associated with an increase in sperm number and a decrease in the frequency of sperm shape abnormalities. Treatment of rodents with cigarette smoke or cigarette smoke constituents produces similar effects on sperm number and morphology. Experimental evidence from humans and rodents suggests that cigarette smoke or nicotine can alter hypothalamic-pituitary interrelationships, stimulating growth hormone, cortisol, vasopressin, and oxytocin release and inhibiting luteinizing hormone and prolactin release. These changes may alter hormonal interrelationships necessary for successful reproduction. Studies in rodents and human and nonhuman primates also suggest that cigarette smoke or nicotine alters the motility of the female reproductive tract, and may impair implantation of the embryo. Analysis of the experimental data available concerning the effects of smoking on reproductive processes suggests an adverse influence on reproduction at several sites from gametogenesis to implantation. The literature on smoking and fertility, however, is surprisingly small. Additional experimentation, as well as epidemiological surveys of human populations, are necessary before it will be possible to make unequivocal statements concerning reproductive interference by cigarette smoke or its components.