Doseresponse relationship between alcohol consumption before and ...

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Jul 6, 2011 - Objective To review systematically and perform meta-analyses on the effect of ..... of the pregnancy period (see Tables S3–S5). Patra et al.
Systematic review

DOI: 10.1111/j.1471-0528.2011.03050.x www.bjog.org

Dose–response relationship between alcohol consumption before and during pregnancy and the risks of low birthweight, preterm birth and small for gestational age (SGA)—a systematic review and meta-analyses J Patra,a,b R Bakker,c,d H Irving,a VWV Jaddoe,c,d S Malini,e J Rehma,b,f,g a Centre for Addiction and Mental Health, Toronto, ON, Canada b Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada c The Generation R Study Group, Erasmus Medical Centre, Rotterdam, The Netherlands d Department of Epidemiology, Erasmus Medical Centre, Rotterdam, The Netherlands e Department of Community Medicine, MKCG Medical College, Orissa, India f Department of Psychiatry, University of Toronto, ON, Canada g Technische Universita¨t Dresden, Klinische Psychologie and Psychotherapie, Dresden, Germany Correspondence: J Patra, Social and Epidemiological Research, Centre for Addiction and Mental Health, 33 Russell Street, Room T-508, Toronto, ON, Canada M5S 2S1. Email [email protected]

Accepted 17 May 2011. Published Online 6 July 2011.

Background Descriptions of the effects of moderate alcohol

consumption during pregnancy on adverse pregnancy outcomes have been inconsistent. Objective To review systematically and perform meta-analyses

on the effect of maternal alcohol exposure on the risk of low birthweight, preterm birth and small for gestational age (SGA). Search strategy Using Medical Subject Headings, a literature

search of MEDLINE, EMBASE, CINAHL, CABS, WHOlist, SIGLE, ETOH, and Web of Science between 1 January 1980 and 1 August 2009 was performed followed by manual searches. Selection criteria Case–control or cohort studies were assessed for

quality (STROBE), 36 available studies were included. Data collection and analysis Two reviewers independently

extracted the information on low birthweight, preterm birth and SGA using a standardised protocol. Meta-analyses on dose– response relationships were performed using linear as well as first-

order and second-order fractional polynomial regressions to estimate best fitting curves to the data. Main results Compared with abstainers, the overall dose–response

relationships for low birthweight and SGA showed no effect up to 10 g pure alcohol/day (an average of about 1 drink/day) and preterm birth showed no effect up to 18 g pure alcohol/day (an average of 1.5 drinks/day); thereafter, the relationship showed a monotonically increasing risk for increasing maternal alcohol consumption. Moderate consumption during pre-pregnancy was associated with reduced risks for all outcomes. Conclusions Dose–response relationship indicates that heavy

alcohol consumption during pregnancy increases the risks of all three outcomes whereas light to moderate alcohol consumption shows no effect. Preventive measures during antenatal consultations should be initiated. Keywords Alcohol, low birthweight, meta-analysis, neonatal devel-

opment, preterm birth, small for gestational age.

Please cite this paper as: Patra J, Bakker R, Irving H, Jaddoe V, Malini S, Rehm J. Dose–response relationship between alcohol consumption before and during pregnancy and the risks of low birthweight, preterm birth and small for gestational age (SGA)—a systematic review and meta-analyses. BJOG 2011;118:1411–1421.

Introduction Many observational studies have been published on the topic of alcohol consumption in pregnant women and its effects on the development of fetus and child. The

association of heavy maternal alcohol consumption during pregnancy and various adverse birth outcomes has been well established.1,2 Also, excessive alcohol consumption during pregnancy is associated with adverse postnatal behavioural development.3 However, studies focused on the

ª 2011 The Authors BJOG An International Journal of Obstetrics and Gynaecology ª 2011 RCOG

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associations of low to moderate alcohol consumption during pregnancy with birth outcomes showed inconsistent results.4–9 In general, low to moderate maternal alcohol consumption is considered as an average of one alcoholic drink at most per day. Some studies did not find any associations, whereas others found adverse or even beneficial effects. A recent systematic review by Henderson et al.10 also reported no convincing evidence for adverse effects of low to moderate maternal alcohol consumption on pregnancy outcomes, such as miscarriage, stillbirth, fetal growth restriction, prematurity, low birthweight, small for gestational age (SGA) at birth and birth defects including fetal alcohol syndrome. The authors were not able to perform a meta-analysis because of the high heterogeneity in the methods of the various studies used in their systematic review. They suggested that differences in results between studies might be the result of differences in study design and in timing and methods of assessment of maternal alcohol consumption. Also, differences in adjustment for possible confounding factors between the studies may explain inconsistent results. The aim of this systematic review and meta-analysis was to assess the dose–response association of maternal alcohol exposure before and during pregnancy with the risks of low birthweight, preterm birth and SGA.

Methods

1 Reported data were from an original study (i.e. no review articles) 2 Cohort or case–control study in which medically confirmed low birthweight (defined as