Researchers from Belgium and Australia assessed the drinking habits of more than 400 women during pregnancy and mapped the facial features of their offspring at the age of 1 year.

The team found that prenatal alcohol exposure - even at low levels - subtly influenced the formation of facial features in the womb, including the nose, chin, and eyes.

Study co-leader Evi Muggli, of the Murdoch Children's Research Institute in Australia, and colleagues recently reported their results in JAMA Pediatrics.

The Centers for Disease Control and Prevention (CDC) state that there is no safe amount of alcohol to drink during pregnancy, nor is there a safe time to drink alcohol while pregnant.

However, a 2015 study from the CDC found that around 1 in 10 expectant mothers in the United States report having consumed alcohol within the past 30 days.

Alcohol consumption during pregnancy can cause a number of physical and developmental problems for offspring, including low birthweight, learning disabilities, small head size, intellectual disabilities, and problems with vision or hearing. These conditions fall under the umbrella of fetal alcohol spectrum disorder (FASD).

It is also known that prenatal alcohol exposure can influence a child's facial development, though the level of alcohol intake that causes such an effect has been unclear.

For their study, Muggli and colleagues set out to investigate how different levels of prenatal alcohol exposure affect facial development.

Using 3-D imaging to map children's facial features

The study included 415 children born to mothers who were part of the Asking Questions about Alcohol in Pregnancy (AQUA) study.

The AQUA study is a longitudinal cohort of almost 1,600 pregnant women, which aims to gain a better understanding of how various amounts of alcohol consumed during pregnancy affect the unborn child.

As part of the study, mothers were asked to complete a questionnaire detailing the frequency and quantity of alcohol intake in the 3 months before pregnancy, as well as in each trimester.

Low alcohol intake was defined as less than 20 grams of alcohol per drinking occasion and less than 70 grams of alcohol per week; moderate intake was defined as 21-49 grams of alcohol per occasion and less than 70 grams per week; high intake was defined as more than 50 grams of alcohol per occasion.

When the children reached 1 year of age, they underwent facial imaging. According to co-lead study author Harry Matthews, of the University of Melbourne in Australia, the team used a "sophisticated 3-D facial analysis technique, mapping something like 7,000 individual dot points on the face."

Women 'should abstain from alcohol during pregnancy'

The researchers found that low, moderate, and high intake of alcohol - particularly in the first trimester of pregnancy - led to changes in the formation of facial features among offspring.

The team notes that these changes were not visible to the naked eye, as they measured less than 2 millimeters. The 3-D imaging technique, however, was able to detect tiny alterations to the nose, lips, and eyes with any level of prenatal alcohol exposure.

Based on their findings, the researchers conclude that drinking even small amounts of alcohol during pregnancy may influence fetal development.

"We were surprised to see that these comparatively low levels of alcohol do have a subtle impact and our findings support national recommendations to abstain from drinking alcohol in pregnancy." Prof. Jane Halliday, Ph.D., Murdoch Childrens Research Institute

"The information from our study is particularly important. It affirms my need to advise women to avoid alcohol during pregnancy and gives me new evidence to support that advice," adds study co-author Elizabeth Elliott , of the University of Sydney in Australia.