Study Finds that Quitting Smoking During Pregnancy Lowers Risk of Preterm Births
There is an important association between maternal cigarette smoking cessation during pregnancy and risk of preterm birth, according to a new Dartmouth-led study published in JAMA Network Open.
The negative health impacts of cigarette smoking during pregnancy—which include low birth weight, delayed intrauterine development, preterm birth, infant mortality, and long-term developmental delays—are well known. In good news, the proportion of women who start their pregnancy as smokers has been declining in recent years.
“Of concern, though, given the substantial benefits of smoking cessation during pregnancy, is the proportion of pre-pregnancy smokers who quit smoking during pregnancy has remained essentially stagnant since 2011,” explains lead author Samir Soneji, PhD, an associate professor at The Dartmouth Institute for Health Policy and Clinical Practice, who collaborated with Hiram Beltrán-Sánchez, PhD, an associate professor at the University of California, Los Angeles, on the study.
The investigators sought to assess the probability of preterm birth among expectant mothers who smoked before pregnancy and quit at the start or during pregnancy. Using data from the U.S. National Center for Health Statistics, they conducted a cross-sectional study of more than 25 million pregnant women (modal age 25-29) who gave birth to live neonates during a six-year period (2011-2017)—measuring their smoking frequency three months prior to pregnancy and for each trimester during pregnancy.
Notably, their analysis not only showed that quitting smoking was associated with reduced risk of preterm birth, it showed that the probability of preterm birth decreased more the earlier smoking cessation occurred in pregnancy—up to a 20 percent relative decrease if cessation occurred at the beginning of pregnancy.