Maternal smoking during pregnancy and asthma during the first year of life: a comparative study between smokers and non-smoker mothers

BACKGROUND We investigated the relationship between maternal smoking in pregnancy and health care problems in the offspring during the first year of life, particularly asthma. MATERIAL AND METHODS A cohort of 648 consecutive infants born at term and alive at Hospital de Sagunto (Valencia, Spain) over one year period was followed for 12 months. Clinical data of the infants were prospectively collected from the database of ambulatory medical records (ABUCASIS) of the Valencia health system. RESULTS Smoking during pregnancy was recorded in 164 (25.3%) mothers. During the first year of life, asthma was diagnosed in 101 infants, with an incidence of 15.7%. The diagnoses of asthma (25.6% vs. 12.3%; P < 0.0001) and bronchiolitis (44.5% vs. 28.6%; P = 0.0002) during the first year of life were more common among infants in the smoking group. The probability of developing asthma during the first year of life was two-fold higher for the male gender and 2.5 times higher when mothers smoked while pregnant. Up to 52% of asthma cases could have been avoided in infants born to smoking mothers if they did not smoke during pregnancy. Infants in the smoking group showed a lower weight and length at birth than infants in the nonsmoking group differences almost disappeared at 6 months and 12 months. CONCLUSION Asthma during the first year of life showed a clear relationship with maternal smoking in pregnancy. Pregnant women should be advised of the significant perinatal risk for respiratory diseases associated with tobacco use.