Fetal growth and maternal alcohol consumption during early pregnancy

Abstract

Objective

The relationship between light maternal alcohol consumption and fetal outcome remains contentious and the professional advice women receive is conflicting. The aim of this large epidemiological study was to examine the relationship between fetal growth and maternal alcohol behaviour before and during early pregnancy.

Study design

Clinical and sociodemographic details of women who delivered a baby weighing ≥500 g during the eight years 2010-18 were analysed. Details on lifestyle behaviour before pregnancy and at the time of the first antenatal hospital visit were computerised using a standardised questionnaire.

Results

Of 68,925 women, 33.6% abstained from alcohol consumption before pregnancy and 98.4% reported they were abstaining at their first antenatal visit. Only 1.2% reported light consumption (1–2 units/week, median 1.0 IQR 1.0), 0.4% reported moderate/heavy consumption (>3 units/week, median 4.0 IQR 4.0) and 0.3% reported binge drinking (>5 units in one sitting, median 3.0 IQR 4.0). Women who consumed alcohol in binges were more likely to be <30years whereas women who consumed alcohol weekly were more likely to be ≥30years. Women who who consumed any alcohol during early pregnancy were more likely to be multiparous, Irish-born, to have an unplanned pregnancy, to be unemployed, on medications for depression or anxiety, current smokers and abusing illicit drugs. In the absence of persistent smoking or illicit drug abuse, there was no relationship between light alcohol consumption during early pregnancy and the subsequent mean birth weight, preterm delivery (%), small-for-gestational age (%) and mean neonatal head circumference.

Conclusion(s)

Women who consume alcohol should continue to be advised of the fetal and maternal risks of heavy consumption and, if applicable, of the need to quit smoking and avoid illicit drugs. However, women who have consumed alcohol before realising that they were pregnant or who consumed alcohol in light amounts during early pregnancy, may be reassured that their alcohol consumption did not impact adversely on their baby’s growth.

Introduction

There is consensus worldwide that women should avoid excessive alcohol consumption or intoxication during pregnancy because it is associated with adverse fetomaternal outcomes [1]. At its most extreme, excessive consumption is associated with Fetal Alcohol Spectrum Disorder (FASD) which consists of as many as four diagnostic entities, including Fetal Alcohol Syndrome (FAS) [2]. The effects of alcohol excess depend on the pattern of exposure, the dose and the developmental stage of the embryo at the time of exposure [2,3]. Although diagnostic criteria are not standardized, a systematic review and meta-analysis of 24 studies estimated that the global prevalence of FASD was 7.7/1000 population with the highest prevalence of 19.8/1000 in the WHO European Region and the lowest of 0.1/1000 in the WHO Eastern Mediterranean Region [2]. There remain, however, significant challenges with recognition, screening and diagnosis when it comes to case ascertainment [4]. There is little consensus worldwide concerning prenatal alcohol exposure (PAE) to light or moderate maternal consumption [5]. Some guidelines recommend that women abstain completely from alcohol from conception until after pregnancy, others recommend that women cap their intake at 1–2 units 2–3 times per week [1]. The lack of consensus is, in part, because many epidemiological studies on PAE have not analysed outcomes for important confounders of fetal growth, such as maternal smoking, or for the patterns or intensity of alcohol consumption before and during pregnancy [6]. The purpose of this observational study was to examine the relationship between maternal alcohol intakes reported in early pregnancy and subsequent fetal growth.