How Alcohol Affects Pregnancy
Two recently-completed studies, one from the U.K. and one from Australia, present new data on the effects of alcohol during pregnancy.
Data from ongoing scientific research continues to point to the adverse effects of high levels of alcohol intake during pregnancy and the potential for severe developmental and other health issues. But these recent studies suggest that light drinking has little or no effect on the developing fetus.
The studies also demonstrate how socioeconomic, educational, and other lifestyle factors of the mother may have large effects on the health of the fetus and child. Researchers suggest that these areas must be considered when evaluating the potential effects of alcohol during pregnancy due to these findings.
In a very large population-based observational study from the UK, children of women who reported light drinking did not show any evidence of impairment on testing for behavioral and emotional problems or cognitive ability when evaluated at age 5. Light drinking was defined as no more than one to two units of alcohol per week or per occasion.
Researchers found that male children of women reporting heavy or binge drinking during pregnancy (7 or more units per week or 6 or more units per occasion) had poorer behavioral scores. Heavy drinking was defined as seven or more units per week or six or more units per occasion.
The effects were less clear among female offspring.
A second study, published in Pediatrics, examined the associations between dose, pattern, and timing of prenatal alcohol exposure (PAE) and birth defects. The study was based on a population in Western Australia and found similar results to the UK study in that there was no association between low or moderate prenatal alcohol exposure and birth defects.
Data was examined from a randomly selected, population-based cohort of non-indigenous women who gave birth to a live infant in Western Australia (WA) between 1995 and 1997. The 4,712 women chosen for the random sample were linked to WA Midwives Notification System and WA Birth Defects Registry data.
Information about maternal alcohol consumption was collected three months after birth for the three-month period before pregnancy and for each trimester separately.
In the WA study, low alcohol consumption was defined as less than seven standard drinks (10g) a week and no more than two drinks on any one day. Women who consumed more than 70g per week were classified as heavy drinkers, and women consuming more than 140g were classified as very heavy drinkers.
Findings indicated that the prevalence of birth defects classified as ARBDs by the IOM was low. Compared with abstinence, heavy prenatal alcohol exposure in the first trimester was associated with an increased odds ratio of 4.6 for birth defects classified as ARBDs, with similar findings after validation through bootstrap analysis.
There was no association between low or moderate prenatal alcohol exposure and birth defects.
Overall, current findings and analysis suggests that while drinking during pregnancy should not be encouraged, there is little evidence to suggest that an occasional drink or light drinking by the mother is associated with harm.
Heavy drinking, however, is associated with serious developmental defects in the fetus including low birth weight, attention and behavioral problems, learning disorders, heart problems and a variety of other growth and development issues.
Source: Boston University Medical Center
Chavis, S. (2010). How Alcohol Affects Pregnancy. Psych Central. Retrieved on July 31, 2015, from http://psychcentral.com/news/2010/10/18/how-alcohol-affects-pregnancy/19678.html