Most Significant Alcohol-Related Damage to Fetus Occurs in Weeks 7-12 of Pregnancy

A new study suggests the most significant alcohol-related damage to fetuses occurs during the seventh through twelfth weeks of pregnancy. However, the researchers emphasized their findings do not indicate it is safe to drink earlier or later in pregnancy. They point out that some women who drink heavily early in their pregnancy miscarry.

The researchers collected information on drinking patterns in 992 pregnant women. Their babies were studied for signs of alcohol exposure, including below-average height or weight, and certain facial characteristics such as a small head circumference, or a flattened cleft between the nose and upper lip, the Los Angeles Times reports.

They found the strongest association between signs of alcohol damage to the fetus and women’s drinking occurred during the second half of the first trimester, the article notes. For each one-drink increase in the average number of drinks a woman had each day, there was a 12 to 25 percent risk in the risk of physical abnormalities related to fetal alcohol syndrome, the researchers report.

Women’s drinking in their third trimester was associated with shorter birth length.

“Clinicians should continue to follow the recommendations to encourage women who are planning a pregnancy or have the potential to become pregnant to avoid alcohol, and to advise women who become pregnant to stop alcohol consumption,” researcher Haruna Sawada Feldman of the University of California, San Diego, said in a news release. “These new findings can also help clinicians quantify the importance of discontinuing alcohol as early as possible.”

The study will be published in the journal Alcoholism: Clinical and Experimental Research.