Although prior studies have shown that smoking reduces preeclampsia risk, the relationship between nicotine level and preeclampsia risk is not known. Our objective was to study the effects of smoking on the incidence of preeclampsia in African-American women using cotinine, a quantitative marker of nicotine.Methods
We performed a secondary analysis of data collected prospectively in Project District of Columbia Healthy Outcomes of Pregnancy Education. Our study included 724 African-American women. Self-reported smoking, cotinine levels, and pregnancy outcomes were examined.Results
Some 18% of participants were smokers. Women with salivary cotinine levels greater than 200 ng/ml had infants with lower birth weights and a higher incidence of small-for-gestational-age infants than women with cotinine levels of 200 ng/ml or less. Exact logistic regression analysis revealed that women with salivary cotinine levels greater than 200 ng/ml had a significantly lower incidence of preeclampsia, compared with women with cotinine levels of 200 ng/ml or less, in unadjusted analysis (odds ratio [OR]=0.16, 95% CI=0–0.90). After controlling for age, parity, and medical comorbidities, the trend was observed, but the effect was no longer significant (adjusted odds ratio [AOR]=0.19, 95% CI=0–1.11). We found no significant differences in preeclampsia rates using lower cutoffs of cotinine exposure. We did not observe a decrease in preeclampsia incidence at low or moderate cotinine levels.Discussion
Women with the highest cotinine levels may have a decreased risk for preeclampsia, although this effect was not significant after controlling for other risk factors.