An Evaluation of the Effects of Smoking on Maternal Oestriol Excretion During Pregnancy and on Fetal Outcome

Summary In 1000 consecutive patients with singleton pregnancies 38.7 per cent were smokers and 13.7 per cent had subnormal oestriol excretion. There was a significant correlation between low oestriol excretion and both intrauterine fetal growth retardation and perinatal mortality (P<0.001). Smoking had a significant correlation with intrauterine growth retardation (P<0.001), but not with perinatal mortality (P<0.05). The incidence of low oestriol excretion in smokers (15.5 per cent) was not significantly different from that in non‐smokers (12.6 per cent) (P<0.25). Further study is required to evaluate the effects of heavy smoking on feto‐placental function. Hypoxia is probably not the important influence causing fetal growth retardation in smokers.