OBJECTIVES: To determine the effects of low-to-moderate levels of maternal alcohol consumption in pregnancy on pregnancy and longer-term offspring outcomes.

SEARCH STRATEGY: Medline, Embase, Web of Science and Psych info from inception to 11 July 2016.

SELECTION CRITERIA: Prospective observational studies, negative control and quasi experimental studies of pregnant women estimating effects of light drinking in pregnancy (</=32 g/week) versus abstaining. Pregnancy outcomes such as birth weight and features of fetal alcohol syndrome were examined.

DATA COLLECTION AND ANALYSIS: One reviewer extracted data and another checked extracted data. Random effects meta-analyses were performed where applicable, and a narrative summary of findings was carried out otherwise.

MAIN RESULTS: 24 cohort and two quasi experimental studies were included. With the exception of birth size and gestational age, there was insufficient data to meta-analyse or make robust conclusions. Odds of small for gestational age (SGA) and preterm birth were higher for babies whose mothers consumed up to 32 g/week versus none, but estimates for preterm birth were also compatible with no association: summary OR 1.08, 95% CI (1.02 to 1.14), I2 0%, (seven studies, all estimates were adjusted) OR 1.10, 95% CI (0.95 to 1.28), I2 60%, (nine studies, includes one unadjusted estimates), respectively. The earliest time points of exposure were used in the analysis.

CONCLUSION: Evidence of the effects of drinking </=32 g/week in pregnancy is sparse. As there was some evidence that even light prenatal alcohol consumption is associated with being SGA and preterm delivery, guidance could advise abstention as a precautionary principle but should explain the paucity of evidence.

Published in Pregnant Women

BACKGROUND: Excessive alcohol consumption during pregnancy has adverse effects on fetal growth and development. Less consistent associations have been shown for the associations of light-to-moderate maternal alcohol consumption during pregnancy with health outcomes in the offspring. Therefore, we examined the associations of light-to-moderate maternal alcohol consumption with various fetal growth characteristics measured in different periods of pregnancy.

METHODS: This study was based on 7333 pregnant women participating in a population-based cohort study. Alcohol consumption habits and fetal growth were assessed in early (gestational age <17.9 weeks), mid- (gestational age 18-24.9 weeks) and late pregnancy (gestational age > or =25 weeks). We assessed the effects of different categories of alcohol consumption (no; less than one drink per week; one to three drinks per week; four to six drinks per week; one drink per day and two to three drinks per day) on repeatedly measured fetal head circumference, abdominal circumference and femur length.

RESULTS: In total, 37% of all mothers continued alcohol consumption during pregnancy, of whom the majority used less than three drinks per week. We observed no differences in growth rates of fetal head circumference, abdominal circumference or femur length between mothers with and without continued alcohol consumption during pregnancy. Compared with mothers without alcohol consumption, mothers with continued alcohol consumption during pregnancy had an increased fetal weight gain [difference 0.61 g (95% confidence interval: 0.18, 1.04) per week]. Cross-sectional analyses in mid- and late pregnancy showed no consistent associations between the number of alcoholic consumptions and fetal growth characteristics. All analyses were adjusted for potential confounders.

CONCLUSIONS: Light-to-moderate maternal alcohol consumption during pregnancy does not adversely affect fetal growth characteristics. Further studies are needed to assess whether moderate alcohol consumption during pregnancy influences organ growth and function in postnatal life.

BACKGROUND: Controversies still exist regarding the existence of a 'safe' level of alcohol intake during pregnancy. The aim of this study was to assess the risk of fetal death (spontaneous abortion and stillbirth) according to maternal alcohol consumption in a large Danish pregnancy cohort.

METHODS: A cohort study carried out within the framework of the Danish National Birth Cohort. A total of the 92 719 participants enrolled in the Danish National Birth Cohort who provided information about lifestyle during first trimester of pregnancy were included in the study. Information about average weekly consumption of alcohol during pregnancy, smoking, coffee drinking, occupational status and reproductive history were obtained by means of computer-assisted telephone interviews. Pregnancy outcomes (spontaneous abortion, stillbirth, live birth and other pregnancy outcome) and gestational age at end of pregnancy were obtained through register linkage with the Civil Registration System and the National Discharge Registry. Data were analysed using Cox regression models, taking the varying gestational age at recruitment and time-dependent co-variables into account.

RESULTS: Fifty-five per cent of the participants abstained from alcohol drinking during pregnancy and only 2.2% reported four or more drinks per week. The adjusted hazard ratios for fetal death in first trimester were 1.66 [95% confidence interval (CI) 1.43-1.92] and 2.82 (95% CI 2.27-3.49) for women who reported 2-3½ drinks per week and 4 or more drinks per week, respectively, and 1.57 (95% CI 1.30-1.90) and 1.73 (95% CI 1.24-2.41) for fetal death during pregnancy weeks 13-16. No increased risk was found for fetal death after 16 weeks of pregnancy.

CONCLUSIONS: Even low amounts of alcohol consumption during early pregnancy increased the risk of spontaneous abortion substantially. The results indicate that the fetus is particularly susceptible to alcohol exposure early in pregnancy.

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.

Published in Pregnant Women
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