Smoking influences male-female birth ratio.
Parental Smoking of more than 20 cigarettes a day may reduce the frequency of conceiving male children. This study of 11,815 liveborn babies suggests that heavy parental smoking around the time of conception reduces the sex ratio of males to females, with the ratio decreasing as cigarette consumption increases. A total of 5,372 mothers with a mean age of 33.6 years provided information about their and their spouses' cigarette use during the periconceptional period -- from 3 months before the last menstruation period to pregnancy confirmation.
The male:female sex ratio of nonsmoking parents was 1.214 (1975:1627), compared to 0.823 (255:310) for two parents who smoked more than 20 cigarettes a day (odds ratio = 0.68, 95% CI = 0.57-0.81, P < .0001). In couples with fathers smoking more than 20 cigarettes a day and mothers who did not smoke, the ratio was 0.984 compared with nonsmoking couples (odds ratio = 0.81, 95% CI = 0.74-0.88, P < .0001). The ratio also appears to decline with maternal smoking, but further research is needed among couples with a nonsmoking father and mother who smokes.
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|Publication:||Southern Medical Journal|
|Article Type:||Brief Article|
|Date:||Oct 1, 2002|
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