Children whose mothers have one or two drinks per week during pregnancy are not at any greater risk for developing behavioral or cognitive problems than children whose mothers abstained completely, according to a new study from British scientists.

Researchers used data from 11,513 children who were part of the U.K. Millennium Cohort Study. They surveyed mothers on the amounts of alcohol they consumed during pregnancy , and followed up with the children at ages 9 months and 3 and 5 years. During home visits, behavior assessments were done with parents, and cognitive tests were done on the children.

The researchers previously published their results after assessments on the then-3-year-old children, showing no disadvantage for those whose mothers drank lightly during pregnancy. The new study addressed concerns that the effects of prenatal alcohol consumption would show up later in a child's life.

“The findings of this paper and our previous work suggest that, up to the age of 5 years, there is no increased risk of poor socioemotional or cognitive developmental outcomes in children born to mothers who drank not more than 1 or 2 units of alcohol per week during pregnancy,” said the authors, who were led by Yvonne Kelly of the department of epidemiology and public health at University College London.

Children born to light drinkers were actually found to perform better on cognitive tests than mothers who abstained entirely, but those differences were erased when socioeconomic status was taken into account.

Drinking during pregnancy has been an issue with some debate. While heavy drinking during pregnancy has been shown to harm the fetus, the effects of small amounts of alcohol have been less clear. A similar debate has occurred with drinking while breastfeeding.

Many women follow the advice that some recommend — without knowing a safe dose, women should avoid alcohol altogether while pregnant.

“The guideline is that there is no safe amount of alcohol,” said Dr. Renee Turchi, medical director of special programs at St. Christopher's Hospital for Children in Philadelphia. “If you're pregnant or think that you could be pregnant, do not consume any alcohol.”

Turchi, who serves on the American Academy of Pediatrics panels for children with disabilities and fetal alcohol spectrum disorder, expressed concern that researchers may have missed some possible deficits in children whose mothers consumed alcohol.

“We don't have any information on school performance, which is a big thing for these kids,” Turchi said.

She said some math and conceptual problems may not have been picked up by tests used by the researchers to measure language and visual-spatial relations, and scales for behavior were not used, just interviews with parents.

“Sometimes the effects of alcohol aren't seen until they hit school age,” Turchi said, adding that the findings might be compelling if they continued to older ages in the children.

“I'm not trying to bash these researchers, it's just a very concerning message,” she said.

The study is not the first to give evidence that very light drinking during pregnancy may not harm the baby.

In 1991, Drs. Joel Alpert and Barry Zuckerman of the Boston University School of Medicine wrote an analysis of studies for the journal Pediatrics in Review that stated, “Our conclusion is that there is no measurable or documented risk from this level [two or fewer drinks per day] of drinking during pregnancy. Therefore, by urging well nourished pregnant women to abstain from alcoholic beverages, we may be turning our attention away from negative health behaviors of far greater danger than consuming a glass of wine or its alcoholic equivalent.”

Zuckerman told My Health News Daily that the findings of his study, which was conducted in the early 1980s, supported the findings of the new BMJ study.

“It's certainly consistent with the experience of pregnant women in France and Italy, and certainly the rest of the world,” he said.

While standard guidance in the United States may be to avoid alcohol entirely during pregnancy, Zuckerman said, “I think that's correct, but I think we have data to suggest otherwise and practice around the world that suggests otherwise.”

“I can only show what the study reports. People can debate the science, but they shouldn’t ignore it,” Zuckerman said.

Zuckerman added that there is no indication that heavy alcohol use is okay.

“At the height, when someone's an alcoholic, then you're really talking about a potential problem,” he said.

The results of the new study were published today (Oct. 5) in the Journal of Epidemiology and Community Health, from the British Medical Journal.