The overall prevalence of smoking during preg-
nancy was 32.7 percent in the province of Nova Sco-
tia. Cigarette smoking was associated with a twofold
increase in the risk of placental abruption (relative risk
(RR) = 2.05, 95 percent confidence interval (CI)
1.75-2.40), with little gradient of increasing relative
risk with increasing number of cigarettes smoked per
day (table 3). Placental abruption was not associated
with alcohol consumption during pregnancy (RR =
0.88, 95 percent CI 0.72-1.08). Adjustments for con-
founders had little influence on the pattern of associ-
ations.