Interactions between smoking and weight in pregnancies complicated by preeclampsia and small-for-gestational-age birth.
Cigarette smoking protects against preeclampsia but increases the risk of small-for-gestational-age birth (SGA). Regarding body weight, the converse is true: obesity elevates rates of preeclampsia but reduces rates of SGA. The authors assessed the combined effects of smoking and weight among US women developing preeclampsia or SGA, studying 7,757 healthy, primigravid women with singleton pregnancies in 1959-1965. Smoking (never, light, heavy), stratified by prepregnancy body mass index (BMI (weight (kg)/height (m)(2)); underweight, overweight, obese), was examined in relation to preeclampsia and SGA. Among underweight (BMI <18.5) and normal-weight (BMI 18.5-24.9) women, smoking decreased the risk of preeclampsia (for heavy smoking, light smoking, nonsmoking, test for trend p = 0.002 for underweight and p = 0.009 for normal weight) after adjustment for age, race, and socioeconomic status. However, among overweight/obese women (BMI >or=25), this trend was not apparent (p = 0.4). Among both underweight and overweight women, smoking significantly increased SGA risk (trend p < 0.001 for underweight and p = 0.02 for overweight/obese). Obesity eliminated the inverse association between smoking and preeclampsia but did not substantially alter the positive association between smoking and SGA. A possible unifying biologic explanation is discussed in this paper.
Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA. repro@pitt.edu
Roberta B
RB
Ness
Jun
J
Zhang
Debra
D
Bass
Mark A
MA
Klebanoff
D000328:Adult; D000704:Analysis of Variance; D015992:Body Mass Index; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D015331:Cohort Studies; D005260:Female; D020073:Gravidity; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D016015:Logistic Models; D008423:Maternal Age; D009765:Obesity / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D011225:Pre-Eclampsia / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D011256:Pregnancy Outcome / Q000453:epidemiology; D012307:Risk Factors; D040242:Risk Reduction Behavior; D012680:Sensitivity and Specificity; D012907:Smoking / Q000009:adverse effects / Q000453:epidemiology; D013851:Thinness / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology; D014481:United States / Q000453:epidemiology