Low to moderate drinking has no adverse effect on babies during pregnancy, researchers have said.
Scientists examined 36 studies on the issue, and found no link between light drinking and premature birth, small babies or low birthweight.
Current government guidance says pregnant women and those trying to conceive should avoid drinking alcohol.
However, the research confirmed that heavy drinking can prove harmful to unborn babies, increasing the risk of a baby being born premature, small for their gestational age or too light.
The study found a “cut off” of 10g to 18g alcohol a day above which there were risks to the growing foetus.
The more women had to drink above this level, the higher the risks, but there were no apparent problems below 10g a day.
Heavy drinkers - those consuming 36g a day - were 23% more likely to have a premature birth than those who did not drink and were more likely to have a small baby.
The researchers concluded: “Dose-response relationship indicates that heavy alcohol consumption during pregnancy increases the risks of all three outcomes whereas light to moderate alcohol consumption shows no effect.”