Researchers assessed the long-term health impact of drinking while pregnant by testing roughly 7,000 10-year-olds on their balancing abilities, a method that offers a reliable reflection of fetal neurodevelopment. For the study, "moderate" alcohol consumption was defined as between three to seven glasses of alcohol a week.
The research team cautioned, however, that other variables, such as maternal wealth and education, might have influenced the findings.
The bottom line, according to study co-author John Mcleod, is that "[there's] certainly no evidence that moderate alcohol use by pregnant mums is good for their kids, and [there are] reasons to be cautious about other messages around 'benefits' of moderate alcohol use by pregnant mums. But equally, [there's] no strong evidence for important harmful effects."
Macleod, chair of clinical epidemiology and primary care with the School of Social and Community Medicine at the University of Bristol, and his colleagues discuss their findings in the June 17 online edition of BMJ Open.
The research comes on the heels of another British study, released in April, which reported no connection between "light" drinking (one to two drinks per week) during pregnancy and increased risk for mental defects among children at the age of 7.
For the new study, the researchers focused on 6,915 children from southwest England who had participated in the larger Avon Longitudinal Study of Parents and Children.
The team first analyzed maternal drinking habits self-reported at both the 18-week mark of pregnancy and then again when the children were 4 years old.
The vast majority of mothers -- 70 percent -- said they drank no alcohol during pregnancy, while 25 percent said they had consumed drinks in the range of "low" (one to two per week) to "moderate" amounts on a weekly basis. Among such drinkers, one in seven had actually engaged in "binge drinking," meaning at least four glasses of alcohol at a sitting.
By the time their children were 4 years of age, 50 percent of the mothers said they consumed three to seven glasses of alcohol weekly. The research team noted that those who drank moderately were older, more affluent and better educated.
At the age of 10, the children underwent two balance tests, which included walking across a balance beam (to assess so-called "dynamic balance"); standing heel-to-toe on a beam with eyes open and closed (to assess "static balance"); and standing on just one leg, eyes open and closed.
The result: moderate maternal (and paternal) drinking while pregnant, and maternal drinking after delivery appeared to be associated with better overall balance, particularly in terms of static balance.
Maternal genetic testing further revealed that the children of mothers who had a so-called "low alcohol" gene (known to reduce drinking behaviors) did not perform worse on the balance tests than those whose mothers didn't have the gene.
Dr. Francine Einstein, from the department of obstetrics & gynecology and women's health at Montefiore Medical Center in New York City, described the study as "interesting" while cautioning that self-reports about alcohol consumption "must be taken with a grain of salt."
"Some women may not recall how much they drank or may under-report use, particularly when there is a social stigma associated with what you are asking about," she noted. So "getting an accurate assessment of how much alcohol a child was exposed to is going to be difficult."
Reading and math skills should also be assessed, she added, as should the impact of other nondrinking factors -- such family wealth -- on a child's performance.
"For these reasons, I would be reluctant to tell my patients that drinking in pregnancy is a good idea," Einstein said.
For more on alcohol and pregnancy, visit the U.S. Centers for Disease Control and Prevention.