Expectant mothers across all social groups drank, while 20 to 80 per cent of those questioned in Australia, New Zealand, Ireland and the United Kingdom reported drinking while pregnant.
The research, published in the online journal BMJ Open, analysed data from three studies that had assessed the amount and type of alcohol drunk before and during pregnancy.
The researchers, from the University of Adelaide, University of Auckland, Liggins Institute and the University of Cambridge, involved 17,244 women who delivered live babies in the four countries.
The prevalence of drinking alcohol ranged from 40 to 80 per cent in Australasia and the UK, and from 20 to 80 per cent in Ireland.
The strongest and most consistent predictor of a heightened risk of drinking alcohol during pregnancy was smoking, with smokers being 17 to 50 per cent more likely to do so.
“Alcohol use during pregnancy is highly prevalent, and evidence from this cross-cohort and cross-country comparison shows that gestational alcohol exposure may occur in over 75% of pregnancies in the UK and Ireland,” the researchers wrote.
Most clinical and government guidelines advise women to stop drinking during pregnancy, the authors wrote.
They found a lower risk of drinking while pregnant in those with a higher level of education, those who had other children, and those were were overweight or obese.
And they found most of those who did drink did so at very low levels.
But seeing as the risks of light drinking were not fully known, they said the widespread consumption of even low levels during pregnancy was a significant public health concern.
“Since most women who consume alcohol do so at lower levels where the offspring growth and development effects are less well understood [than at higher levels], the widespread consumption of even low levels of alcohol during pregnancy is a significant public health concern,” they concluded.
Perinatal Psychiatrist Dr Mark Huthwaite from the University of Otago said the study was surprising, given the amount of information out there about pregnancy and drinking.
“Given the level of education and ages of those most likely to consume alcohol during pregnancy one might simply expect that these pregnant women ought to know better,” he said.
“Is it that miscarriages are now considered a mere nuisance and rather inconsequential? Or possibly are the effects of foetal alcohol spectrum disorder so subtle and presenting later in the child’s life so as not to be considered of much significance?”
Obstetrician Professor Lesley McCowan from the University of Auckland added there was never any safe levels of drinking when pregnant.
“As there is no known safe level of alcohol use in pregnancy the best advice is not to drink alcohol in pregnancy.”