Association of Maternal Cigarette Smoking and Smoking Cessation With Preterm Birth

Key Points Question Does an association exist between maternal cigarette smoking cessation during pregnancy and risk of preterm birth? Findings In this cross-sectional study of more than 25 million pregnant women, only approximately 1 of 4 women who smoked prior to pregnancy quit throughout pregnancy, and approximately 1 of 2 women who smoked during their pregnancy smoked 10 or more cigarettes per day. Cigarette smoking cessation, especially early in pregnancy, was associated with reduced risk of preterm birth (relative decrease up to 20%) even for high-frequency cigarette smokers. Meaning Greater emphasis on smoking cessation among expectant mothers who smoke may be associated with a lower burden of preterm birth.