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 wo men who smoke? STUDY DESIGN: Single births in Sweden from 1987 through 1993 to nulliparous women aged 15 to 34 years (N = 317,652) were incl uded. Poisson regression analyses were used to calculate adjusted rela tive risks and rates of adverse pregnancy outcomes. RESULTS: Maternal smoking was associated with significantly reduced risks of mild and se vere preeclampsia (relative risks = 0.6 and 0.5, respectively). In pre gnancies with severe preeclampsia, smoking at least 10 cigarettes per day was associated with increased rates of perinatal mortality (from 2 4 to 36 per 1000), abruptio placentae (from 31 to 67 per 1000), and be ing small for gestational age (from 28% to 68%), whereas the correspon ding smoking-related increases in rates in nonhypertensive pregnancies were considerably less. CONCLUSIONS: Smokers in whom preeclampsia dev elops have Very high risks of perinatal mortality, abruptio placentae, and small-for-gestational-age infants.