Heavy drinking in pregnancy can increase risk of low birth weight, preterm birth and size for age

Heavy alcohol consumption during pregnancy increases the risk of low birth weight, preterm birth and small size for gestational age, confirms a study by the Centre for Addiction and Mental Health (CAMH).

The researchers found that these effects were related to the dose of alcohol – that is, the more heavily a pregnant woman drank each day, the higher the risk of these outcomes. They looked at 36 previous studies into alcohol consumption and birth outcomes. This review was published in BJOG: An International Journal of Obstetrics and Gynaecology.

The review found that compared to non-drinking mothers, alcohol consumption of three drinks or 36 grams a day increased the risk of having a preterm birth by 23 per cent. The risk of low birth weight and small size also increased when mothers consumed more than one drink a day, or approximately 12 g. Low to moderate maternal alcohol consumption is considered on average as one alcoholic drink per day.

"This review indicates that any drinking beyond light consumption during pregnancy increases the risks of all three outcomes," says Dr. Jayadeep Patra, a CAMH research scientist in Social and Epidemiological Research. "It is difficult to know how many units of alcohol there are in a glass, so the current best advice for women is to abstain from drinking during pregnancy. It is important that a healthy lifestyle is promoted to women during any contact with professionals during pregnancy to emphasize the harmful effects alcohol consumption can have."

This review did not look at the many other possible effects of alcohol consumption during pregnancy and other studies have shown that low to moderate alcohol consumption may be associated with negative outcomes. CAMH believes that there is no safe level of consumption during pregnancy and the only way to ensure the health of a child is to abstain from alcohol during pregnancy.

(Source: Centre for Addiction and Mental Health (CAMH): BJOG: An International Journal of Obstetrics and Gynaecology)

More information

For more information on drinking alcohol, including drinking disorders and alcohol's effect on the body, as well as some useful tools, see Alcohol and Drinking.

For more information about pregnancy, including preconception advice, stages of pregnancy, investigations, complications, living with pregnancy and birth, see Pregnancy.