SAN FRANCISCO – The majority of pregnant teens who smoked in a large population-based cohort study continued smoking throughout pregnancy, and those teens had a higher rate of preterm birth than did those who quit at any time during pregnancy.
Those who quit in the first trimester, however, had the greatest reduction in the risk of preterm birth, Dr. Beth Moore reported during a poster session at the annual meeting of the American College of Obstetricians and Gynecologists.
The findings underscore the need to counsel teen mothers that smoking cessation at any point in pregnancy will reduce the risk for preterm birth, Dr. Moore said. “Targeted counseling and interventions should focus on early smoking cessation in this group of mothers who are at an inherently high risk of preterm birth, as it results in the most substantial risk reduction for delivering prior to 37 weeks.”
Of 96,599 teens who were included in the analysis, 31% smoked during the 3 months prior to conception. Of those, 6,508 (22%) quit during the first trimester, and 17,804 (about 60%) smoked throughout pregnancy. The remainder quit smoking during the second or third trimester, according to Dr. Moore, of the department of maternal-fetal medicine at the University of Cincinnati.
The baseline rate of preterm birth in the study cohort was 11%; the rate among those who smoked throughout pregnancy was 13%.
The risk of preterm birth was reduced by about 24% (odds ratio, 0.76) among those who quit smoking during the first trimester, and was reduced by about 12% (OR, 0.88) among those who quit at any point during pregnancy, she said.
Compared with older women, teens are already at increased risk of preterm birth, and smoking further increases that risk, Dr. Moore said.
To assess the effects of smoking cessation on preterm birth risk in teens, she and her colleagues retrospectively reviewed all non-anomalous singleton birth records in Ohio during the study period. Of the 1,003,532 eligible births recorded during that time, the 96,599 included in the current analysis were to those under age 20 years for whom smoking data were available.
The association between smoking cessation and preterm birth risk was assessed by logistic regression after adjusting for maternal race, Medicaid enrollment, and marital status.
The authors reported having no disclosures.