A new British study that finds that pregnant women can safely have as many as two drinks a week without harming their babies is generating controversy.

The study involving more than 11,000 five-year-olds found children born to "light" drinkers did not suffer from poor behavioural or intellectual growth. In fact, the study found they actually scored higher on cognitive tests than children born to teetotallers.

The study, which appears in the Journal of Epidemiology and Community Health, defined light drinking as no more than 175 millilitres of wine a week, or 50 millimetres of spirits or just under a pint of beer. Moderate pregnant drinkers had up to six drinks per week or five drinks at once. Heavy binge drinkers consumed more.

The children took a series of tests at age three and again at age five that evaluated their behavioural, emotional and intellectual development.

The researchers, led by Yvonne Kelly of the epidemiology and public health department at University College London, found that the children whose mothers were heavy drinkers were more likely to be hyperactive and have behavioural and emotional problems than those whose mothers did not drink.

But the study found no evidence that light drinking during pregnancy caused emotional or learning problems in children through the age of five. In fact, in some tests of vocabulary and pattern creation, boys actually did better if their moms drank a little during pregnancy, compared to those whose mothers abstained from alcohol.

Beth Schneider, who is eight months pregnant with her first child, says she doesn't think there's anything wrong with having a drink once in a while.

"I don't drink every single day," she said. "I'm a firm believer that everything in moderation is okay."

In Canada and the U.S., women are advised not to drink at all during pregnancy because of worries about fetal alcohol syndrome. Doctors usually explain that since no safe threshold for drinking alcohol during pregnancy has been found, it's best not to drink at all.

Health Canada even goes so far as to advise women who are sexually active and not using birth control to avoid drinking alcohol, because of fears of fetal alcohol syndrome.

But in the U.K., the attitudes about drinking during pregnancy have been a little more relaxed. For years, women there have been advised not to drink during the first trimester of their pregnancy but told they can safely have a drink or two a week after that.

That advice changed in 2007, when the U.K. Department of Health updated their guidelines to say pregnant women should avoid alcohol altogether, as should women trying to get pregnant.

This study is re-igniting the debate and raising the ire of public health officials and scientists who have long campaigned against any amount of drinking in pregnancy.

"Drinking very little is probably okay," said Dr. Michael Broadman, an obstetrician at Mount Sinai Medical Centre in New York.

He estimates that about 15 per cent of women still drink during pregnancy.

But pediatrician Gideon Koren says it's unclear how small an amount may be safe.

"We clearly know that alcohol is a poison for the brain of the baby," he said. "So the question is why on earth will anyone who planned pregnancy would want to put a poison into their system -- even in small amounts."

Lead researcher Kelly notes in her study that mothers who reported drinking low levels were more economically and socially advantaged compared to other groups.

Children from households with relatively high incomes tend to perform better on behavioural and cognitive tests, studies have found, while their mothers tend to have access to better prenatal care.

Prof. Wayne Hall, from the University of Queensland's School of Population Health, said it was "highly unlikely" that light drinking alone carried a benefit for children.

"It is much more likely that women who report drinking these small quantities have children at lower risk of developing behaviour disorders because they have better diets, are healthier, use antenatal care, are better educated (and) probably drink alcohol with meals," he told the Sydney Morning Herald.

With a report from CTV's Omar Sachedina