Smoking during pregnancy, stillbirth and abruptio placentae

In a prospective investigation on 9,169 pregnant women which showed a substantial increase in stillbirths among smokers, a large proportion of this increase is due to abruptio placentae. The percentage of smokers in this category rises to 46% while it is only 12% in the group of livebirths. Smoking appears to be an important risk factor in this occurence, the etiology of which is little known. The effect of parity and its possible interaction with smoking are discussed.