Prenatal weight gain following smoking cessation

ObjectiveTo evaluate the association of changes in smoking habit with maternal weight gain.Study designWe questioned 4000 pregnant women ≥20 years about previous and current smoking habits during a second trimester visit to general prenatal clinics in 6 Brazilian cities, from 1991 to 1995, and followed their weight, through chart review, to term.ResultsOf women who reported stopping smoking (915, 23% of the total), 240 (26.2%) stopped during pregnancy. The median number of cigarettes smoked/day among those who reported continued smoking (717, 18%) decreased from 10 to 5 with pregnancy. In linear regression models adjusting for age, educational attainment, ethnicity, prepregnancy body mass index, parity and clinical center, ex-smokers gained 1.03 kg (95%CI 0.59–1.46) more than those reporting never smoking, this difference being greater: 1.54 kg (95%CI 0.78–2.30) in those who reported quitting while pregnant. The size of weight gain in both continuing smokers and ex-smokers was proportional to the reduction in daily number of cigarettes smoked during pregnancy, being 0.38 kg (95%CI 0.07–0.68) greater for each 10 cigarettes reduced (p = 0.007).ConclusionDecreasing the quantity of cigarettes smoked in pregnancy, although important for maternal and child health, is associated with maternal weight gain.