Maternal smoking causes fetal hypoxia: Experimental evidence

Cigarette smoking during pregnancy has been related to poor perinatal outcome. To investigate the changes in maternal and fetal arterial blood gases associated with smoking, five chronically catheterized pregnant rhesus monkeys were exposed to standard cigarette smoke (N = 5) and nicotine-free herbal cigarette smoke (N = 3). The only consistently reproducible and significant finding was a drop in fetal Po₂. The timing of the decline in Po₂ and the similar responses to standard and nicotine-free cigarette smoke make carboxyhemoglobin the most likely causative factor.