A systematic review of maternal smoking during pregnancy and fetal measurements with meta-analysis.

Miriam Abraham,Graham Devereux,Salem Alramadhan,Steve Turner,Vincent W V Jaddoe,Geir W Jacobsen,Peter Hindmarsh,Wojciech Sobala,Liesbeth Duijts,Sarah Crozier,Keith M Godfrey,Wojciech Hanke,Carmen Iniguez,Herman T Den Dekker,Torstein Vik

doi:10.1371/journal.pone.0170946

Abstract

BackgroundMaternal smoking during pregnancy is linked to reduced birth weight but the gestation at onset of this relationship is not certain. We present a systematic review of the literature describing associations between maternal smoking during pregnancy and ultrasound measurements of fetal size, together with an accompanying meta-analysis.MethodsStudies were selected from electronic databases (OVID, EMBASE and Google Scholar) that examined associations between maternal smoking or smoke exposure and antenatal fetal ultrasound measurements. Outcome measures were first, second or third trimester fetal measurements.ResultsThere were 284 abstracts identified, 16 papers were included in the review and the meta-analysis included data from eight populations. Maternal smoking was associated with reduced second trimester head size (mean reduction 0.09 standard deviation (SD) [95% CI 0.01, 0.16]) and femur length (0.06 [0.01, 0.10]) and reduced third trimester head size (0.18 SD [0.13, 0.23]), femur length (0.27 SD [0.21, 0.32]) and estimated fetal weight (0.18 SD [0.11, 0.24]). Higher maternal cigarette consumption was associated with a lower z score for head size in the second (mean difference 0.09 SD [0, 0.19]) and third (0.15 SD [0.03, 0.26]) trimesters compared to lower consumption. Fetal measurements were not reduced for those whose mothers quit before or after becoming pregnant compared to mothers who had never smoked.ConclusionsMaternal smoking during pregnancy is associated with reduced fetal measurements after the first trimester, particularly reduced head size and femur length. These effects may be attenuated if mothers quit or reduce cigarette consumption during pregnancy.

Highlights

Maternal smoking during pregnancy is associated with a reduction in birth weight of approximately 250g and is known to adversely affect the health of both fetus and mother.[1]
Maternal smoking was associated with reduced second trimester head size (mean reduction 0.09 standard deviation (SD) [95% CI 0.01, 0.16]) and femur length (0.06 [0.01, 0.10]) and reduced third trimester head size (0.18 standard deviations (SD) [0.13, 0.23]), femur length (0.27 SD [0.21, 0.32]) and estimated fetal weight (0.18 SD [0.11, 0.24])
Higher maternal cigarette consumption was associated with a lower z score for head size in the second and third (0.15 SD [0.03, 0.26]) trimesters compared to lower consumption

Summary

Introduction

Maternal smoking during pregnancy is associated with a reduction in birth weight of approximately 250g and is known to adversely affect the health of both fetus and mother.[1]. Maternal smoking is associated with reduced second trimester growth in some studies[2,3] but not all[4] and abdominal and proximal muscle growth restriction has been linked to maternal smoking in one population[5] but to peripheral fetal growth (i.e. femur length) in others.[2,3] One study reported an association between exposure to maternal smoking and increased fetal head and arm growth.[6] Here we report a systematic review of the literature with meta-analysis to answer the question “at which gestational ages are the associations between exposure to maternal smoking apparent?” In secondary analyses we sought to relate fetal size to high or low cigarette consumption and the cessation of smoking before or during pregnancy. We present a systematic review of the literature describing associations between maternal smoking during pregnancy and ultrasound measurements of fetal size, together with an accompanying meta-analysis

Methods

Results

Conclusion