Infant weight and parental smoking habits.

A study of 1192 live white births occurring 1963 in Massachusetts revealed a strong correlation between infant weight and smoking during gestation. Both male and female infants born to mothers smoking 1-2 packs of cigarettes a day while pregnant weighed between 6-12 ounces less than those born to nonsmokers. One year later the infants weighted the same as the nonsmoking offspring. No correlation was found between paternal smoking habits and infant weight. Among female infants birth weights increased when the mother reduced her smoking when pregnant. A similar correlation could not be made among male infants. The difference in birth weights between nonsmoking mothers and those who smoke a pack a day or more is greater in the higher birth orders.