Effects of smoking and preeclampsia on birth weight for gestational age

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.

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.

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.

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.