Low birth weight and neonatal mortality rate related to maternal smoking and socioeconomic status

Abstract

Neonatal deaths occurring over a 10 year period among infants born to nonsmoking and smoking mothers enumerated in a nonofficial census of Washington County, Maryland, were compared with a sample of live births from the same population. In addition to maternal smoking, low birth weight, and neonatal mortality rate, a considerable number of demographic and socioeconomic characteristics were studied. Smoking mothers consistently had a higher proportion of small babies regardless of almost all other characteristics. Neonatal mortality rate was approximately 40 per cent higher among infants born to smokers than among those born to nonsmokers. The excess among smokers was most marked among families who ranked low on socioeconomic characteristics. The hypothesis is advanced that hypoxia resulting from increased maternal and fetal carboxyhemoglobin levels is the factor responsible for both the decrease in birth weight and the increase in neonatal mortality rate among infants born to smoking mothers.