Prenatal smoking exposure and asymmetric fetal growth restriction

Abstract

Background: Prenatal smoking exposure causes intrauterine fetal growth restriction (IUGR), although its effects on fetal proportionality are less clearly defined.Aim: The present study assessed fetal proportionality in babies with IUGR using maternal salivary cotinine to indicate maternal smoking exposure.Subjects and methods: A case-control study at the Liverpool Women's Hospital, UK of babies with asymmetric and symmetric IUGR and non-growth restricted babies was carried out.Results: 270 white women including 90 IUGR cases and 180 controls were enrolled. Asymmetry presented in 52.2% of IUGR cases. Geometric mean maternal cotinine concentration was higher with asymmetric (p=0.002) than symmetric IUGR (p=0.07), when compared to controls. Maternal smoking exposure was independently associated with asymmetric IUGR (OR 2.4, 95% CI, 1.5–4.4, p≤0.001). Maternal anaemia was more frequent in babies with symmetric IUGR (OR 1.9, 1.3–3.4, p=0.002), but not in asymmetric babies. Rohrer's index ranged between 1.64 and 2.25 for asymmetric infants and significantly decreased with increasing maternal cotinine concentration in IUGR babies. Increased cotinine was not associated with shortened gestational age in IUGR babies.Conclusions: Asymmetric IUGR occurred more frequently in heavy smokers. Stopping smoking even late in pregnancymay be beneficial for improved fetal outcomes. Symmetric IUGR was associated with maternal anaemia, highlighting the importance of prenatal nutritional status.