The effect of maternal smoking on carboxyhemoglobin levels and acid-base balance of the fetus.

Results are presented showing a dose-related effect of maternal smoking during pregnancy on cord blood carboxyhemoglobin levels. These elevated cord blood carboxyhemoglobin levels are associated with decreased pH and pO2 levels and raised pCO2 levels. This evidence of chronic intrauterine hypoxia in the infants of mothers who smoke during pregnancy provides a potential mechanism for the reduced birthweight found in these infants.