The paradoxical effect of smoking in preeclamptic pregnancies: Smoking reduces the incidence but increases the rates of perinatal mortality, abruptio placentae, and intrauterine growth restriction

OBJECTIVES: Smoking is associated with a reduced risk of preeclampsia, but what is the outcome of pregnancy when preeclampsia develops in women who smoke? STUDY DESIGN: Single births in Sweden from 1987 through 1993 to nulliparous women aged 15 to 34 years (N = 317,652) were included. Poisson regression analyses were used to calculate adjusted relative risks and rates of adverse pregnancy outcomes. RESULTS: Maternal smoking was associated with significantly reduced risks of mild and severe preeclampsia (relative risks = 0.6 and 0.5, respectively). In pregnancies with severe preeclampsia, smoking at least 10 cigarettes per day was associated with increased rates of perinatal mortality (from 24 to 36 per 1000), abruptio placentae (from 31 to 67 per 1000), and being small for gestational age (from 28% to 68%), whereas the corresponding smoking-related increases in rates in nonhypertensive pregnancies were considerably less. CONCLUSIONS: Smokers in whom preeclampsia develops have very high risks of perinatal mortality, abruptio placentae, and small-for-gestational-age infants.(Am J Obstet Gynecol 1997;177:156-61)