Effects of cigarette smoking, alcohol, coffee and tea consumption on preterm delivery.

A case-control study of 175 mothers of singleton, preterm infants and 313 mothers of singleton, term infants was undertaken at Yale-New Haven Hospital during 1977 to explore possible risk factors of preterm delivery. Heavy alcohol consumption (an average of two or more drinks per day) during the pregnancy was associated with an approximately 3-fold risk of preterm delivery. Women who smoked 10 or more cigarettes per day were also at an increased risk of a preterm delivery, but the effect of cigarette smoking was less pronounced once confounding variables had been taken into account. No association was observed between coffee drinking and shortened gestations. Tea consumption, especially four or more cups of tea per day, was more frequent among women with a preterm as compared to a term infant, but no significant relation was evident between heavy tea consumption and preterm delivery after controlling for the effects of other risk factors.