We’re trying for a baby –  is it likely to harm the foetus if I drink alcohol in the weeks before I find out I’m pregnant?

Doctoral researcher Briana Lees from the University of Sydney has just led a study into the effect of low levels of alcohol consumed by mothers in early pregnancy. She says: “Drinking alcohol during any stage of pregnancy (including before pregnancy is known) can increase the risk of harm to the developing embryo/foetus.

“When a pregnant woman consumes alcohol, ethanol crosses the placenta and exposes the unborn child to the same, or higher, alcohol concentrations as the mother. While alcohol can cause harm to any organ or system, the developing brain seems to be the most sensitive. The brain and the rest of the central nervous system begin developing approximately two to three weeks after conception and remain sensitive to harm from alcohol throughout the pregnancy.

“There’s evidence to suggest the brain is most sensitive to alcohol during the first trimester, including the period before the mother is aware she’s pregnant. The greater the frequency and quantity of alcohol consumed, the greater the risk of harm to the unborn child.

“A common question among families planning pregnancies has been whether there’s evidence of a safe level of maternal alcohol consumption that doesn’t increase harm to the unborn child. We recently published a study examining low-level alcohol use during the early stages of pregnancy and risks of harm in offspring aged nine to 10. The sample included 9,719 children and their parents, and 25% of these children had been exposed to alcohol before the mother knew she was pregnant. On average, these women found out they were pregnant at six weeks and about 80% stopped drinking alcohol at this stage.

“We found drinking just one or two standard drinks per occasion before knowing of pregnancy was associated with subtle differences in the child’s brain structure. These brain differences in exposed children were related to emotional and behavioural problems, including higher levels of anxiety, depression and poor attention. We found the more the child was exposed to alcohol in utero before the mother knew she was pregnant, the greater the likelihood of long-term harm.

“The results remained consistent when we accounted for other parental and environmental factors. Genetics also play an important role in determining the risk of harm to an unborn child, with some genotypes providing protection and others increasing risk associated with alcohol. This makes it hard to predict the exact level of risk an unborn child may have from alcohol in each individual pregnancy.

“Overall, there’s growing scientific evidence to indicate that any alcohol use during any stage of pregnancy increases the risk of long-term harm to the unborn child. To prevent risk of harm to your child, the safest option is to avoid alcohol when trying for a baby and during the entire pregnancy.”