The effects of smoking on labour after uncomplicated pregnancy: a comparison between the progress and outcome of labour in 400 smokers and 400 matched non-smokers.

A comparison was made between the progress of labour and its outcome after an uncomplicated pregnancy, in 400 smokers and 400 non-smokers. Strict selection criteria were applied to eliminate, as far as possible, the variables which might have influenced labour in both groups and to ensure that the two groups of women were matched. The duration of labour was longer in smokers, who also had a higher incidence of caesarean sections. Smokers had a higher incidence of retained placenta and postpartum haemorrhage. The neonates of smokers had a higher incidence of problems in the immediate post-delivery period.