The Timing and Patterns of Drinking During Pregnancy also Linked to Varying Effects on Fetal and Child Development: Study

When and how mothers drink alcohol during pregnancy has major implications for fetal and child development, according to two new studies in Alcohol: Clinical & Experimental Research. The effects of prenatal alcohol exposure (PAE) include stillbirth, preterm delivery, and fetal alcohol spectrum disorder (FASD). In US schools, 2–5% of children have FASD, which is linked to impaired growth and development, including cognitive function.

Most studies on PAE and FASD involve birthing parents whose alcohol use was chronic and heavy. Much less is known about what lower levels of drinking-a far more common circumstance-do to fetal development. In two US studies (which were conducted independently), researchers investigated the impacts of varying patterns of maternal alcohol consumption on fetal and developmental outcomes.

One team of researchers based in New Mexico worked with 281 mother-infant pairs. They assessed the birthing parent’s drinking behaviors in the weeks close to conception, before pregnancies become apparent, and through pregnancy. Using statistical analysis, they examined associations between drinking patterns, fetal growth, and gestational age at delivery. Another team examined data drawn from 2,227 people living in four US cities from grade school to early adulthood. This multi-site team used statistical analysis to explore the relationship between drinking frequency and the amount consumed per drinking occasion with measures of cognitive function in childhood, adolescence, and young adulthood.

Among the New Mexico participants, 84% of birthing parents reported at least one binge drinking episode during a month around their last menstrual period, when they averaged 14 drinks per week. During the second trimester, their alcohol consumption was much lower-approximately 1 drink per week – and reduced further to less than 1 drink per month in the third trimester. Earlier gestational age at delivery was related to the average amount of drinking per day during both the weeks close to conception and throughout pregnancy, as well as to mild-moderate PAE and binge drinking.

The amount of alcohol mothers consumed during pregnancy, specifically the maximum number of drinks in a 24-hour period, was also related to the reduced birth length percentile in newborns.In the multi-site study, the total amount of alcohol consumed by the mother during pregnancy correlated with a modest decline in her child’s cognitive function. However, when the frequency of drinking was considered separately from the amount drunk per occasion, the influences of different patterns of alcohol exposure were revealed.

The more complex model showed a contrast between children born to mothers who infrequently consumed less than three drinks per occasion (with virtually no effect on their cognitive function) and those whose mothers drank infrequently at higher levels (with a larger effect on their cognitive function). The amount consumed per occasion had the greatest effect on children born to women who drank at least twice a week. Among mothers who drank < 1 drink/occasion, frequency of drinking had virtually no effect, whereas when mothers drank moderate or large amounts/occasion, frequency of drinking was associated with dose-dependent declines in their children’s cognitive proficiency.

The New Mexico study underscores the impact of PAE very early in pregnancy and the impact of as little as one drink per week or less later in pregnancy on preterm delivery. The findings on infrequent high exposure in the multi-site study add to evidence of binge drinking as a key determinant of FASD impairment. These varying statistical approaches thus provide a more nuanced evaluation of drinking behaviors and their effects on fetal development.

Reference:

Jacobson JL, Akkaya-Hocagil T, Jacobson SW, Coles CD, Richardson GA, Olson HC, Day NL, Carter RC, Dodge NC, Dang KD, Cook RJ, Ryan LM. A dose-response analysis of the effects of prenatal alcohol exposure on cognitive development. Alcohol Clin Exp Res (Hoboken). 2024 Mar 30. doi: 10.1111/acer.15283.