Women who drink alcohol in the early stages of pregnancy won't harm their child's development, according to new research.
Danish researchers looked at the impact low, moderate, high and binge drinking by pregnant women had on their children by the time they turned five.
They found children of mothers who consumed up to eight drinks a week had no difference in attention span to those whose mothers had abstained.
But what surprised the researchers most was that binge drinking more than five drinks in one sitting in the early stages of pregnancy did not appear to affect a child's neurological development.
"We were not so surprised to find no effects from lower levels of drinking, as previous research suggested this, but we didn't even find subtle effects caused by low to moderate and binge drinking," study co-author Professor Ulrik Kesmodel told the UK's Daily Mail.
However, children of mothers who drank high levels of alcohol nine or more drinks per week appeared to have a lower attention span.
The study authors said high prenatal exposure to alcohol has long been associated with adverse effects on neurodevelopment.
Heavy drinking throughout pregnancy is known to cause foetal alcohol spectrum disorder, which can lead to behavioural problems, intellectual disability and distinct facial features.
"Areas such as intelligence, attention and executive functions have been found to be particularly vulnerable. Less is known about the effects of low to moderate, weekly average consumption levels and binge drinking," the authors wrote.
Professor Kesmodel said newly pregnant women are often concerned about binge drinking before they realise they had conceived.
"These findings, which were unexpected, should bring some comfort to women if they were drinking before they realised they were pregnant," he said.
Dr Alex Wodak, senior staff specialist at St Vincent's Hospital, says more research needs to be done.
"[Until now] binge drinking has been thought to be more dangerous to the baby … than high sustained levels," he told ninemsn.
"The research is limited in quantity and quality [but this] data is an important addition to what exists in this area."
Until scientists can pinpoint a precise safe level to drink, the authors and other experts recommend women avoid alcohol while pregnant.
"What worries a lot of people is that for every case of [foetal alcohol spectrum disorder] that is very obvious, there are probably other cases with more subtle changes that go unrecognised," Dr Wodak said.
Almost 1630 women took part in the research and had their drinking habits recorded throughout pregnancy.
Low intake was defined as one to four drinks a week, moderate was five to eight drinks per week and high levels were nine or more drinks a week. Binge drinking was defined as more than five drinks in one sitting.
In Denmark, one standard drink contains 12 grams of alcohol, compared to 10 grams in Australia.
The Australian Government National Health and Medical Research Council advises women who are pregnant or planning a pregnancy to avoid alcohol.