Objective: A counterintuitive interaction between smoking during pregnancy and preeclampsia on birth weight for gestational age (BWGA) outcomes was recently reported. In this report, we examine the relationship between these factors in a well-documented study population with exposure data on trimester of maternal smoking.
Methods: Preeclamptic (n = 238), gestational hypertensive (n = 219), and normotensive women (n = 342) were selected from live-births to nulliparous Iowa women. Disease status was verified by medical chart review, and smoking exposure was assessed by self-report. Fetal growth was assessed as z-score of BWGA. Multiple linear regression was used to test for the association of maternal smoking and preeclampsia with BWGA z-score.
Results: There was no interaction between smoking with preeclampsia or gestational hypertension on fetal growth. BWGA z-scores were significantly lower among women with preeclampsia and those who smoked any time during pregnancy (β = -0.33, p = <0.0001 and β = -0.25, p = 0.05) compared to normotensive and non-smoking women, respectively. Infants of women with gestational hypertension were comparable in size to infants born to normotensive women.
Conclusions: Women who developed preeclampsia and those who smoked during pregnancy delivered infants that were significantly smaller than infants of women who did not develop preeclampsia and non-smoking women, respectively.
Keywords: Epidemiology; fetal growth; low birth weight; pregnancy; z-score.