Drinks with caffeine are safe 'in moderation' for pregnant women
Previous research has come to mixed conclusions, though most has suggested there is no risk to pregnant women.
In the UK experts advise pregnant women to drink no more than four cups of coffee a day.
In this latest study, Swedish researchers followed over 850 women through their pregnancies between 1993 and 1998.
The researchers, from the Karolinska Institute and Uppsala University said there was no association between caffeine consumption and birth weight, how far the pregnancy has progressed before the baby is born, and poor foetal growth during pregnancy.
The mother's blood was also checked for cotinine, a substance produced when the body breaks down nicotine, as an indicator of smoking levels.
What women drank
Researchers were asked if they had had coffee, tea, cocoa, chocolate, soft drinks or caffeine-containing medication.
Each substance was given an estimated caffeine level, so 150ml of brewed coffee was estimated to equate to 90mg of caffeine, and 150ml of a soft-cola drink to 15mg.
Caffeine intake was classed as under 100mcg per day, 100 to 299mg, 300 to 499mg and 500mg plus.
Women were questioned about their daily intake from the time of estimated conception (two weeks after the last period) onwards.
'No relation'
Writing in the American Journal of Epidemiology, the team led by Britt Clausson, said: "Our study finds no support for an association between moderate caffeine consumption during pregnancy and restricted foetal growth."
Dr Wendy Doyle of the British Dietetic Association told BBC News Online: "All the advice is that pregnant women can have caffeine in moderation.
"There is more evidence to support what a lot of other studies have said, that there doesn't appear to be a relation between low birth weight and caffeine intake.
But she cautioned that there was evidence that high consumption of caffeine could increase the risk of miscarriage in early pregnancy.
Roger Cook, spokesman for the British Coffee Association, said: "This study is further evidence that coffee drinking in moderation during pregnancy is absolutely safe."