A leading Australian doctor says it is best for pregnant women to avoid alcohol, despite a US book that says light drinking is safe.
The book, Expecting Better: Why the Conventional Pregnancy Wisdom Is Wrong, says there is no statistical evidence to back medical advice about avoiding alcohol, caffeine and undercooked foods.
The author, University of Chicago economist Emily Oster, says heavy drinking is obviously a bad idea. However, she says there is no credible evidence that having a glass of wine a day during the second and third trimesters would have any cognitive impact on a child.
She also claims it is acceptable to drink four cups of coffee a day and eat forbidden foods like ham.
However, Dr Steve Robson, vice-president of the Royal Australian College of Obstetricians and Gynaecologists, says it is best to err on the side of caution.
Even though there is no firm evidence against light drinking, "it is probably best not to drink at all".
This advice could change in future, but it is hard to prove either way.
"It is not something you can test. You can't ask pregnant women to drink and see what happens to their baby."
He says, however, that pregnant women who drink or get drunk before they know they are pregnant should not be overly alarmed.
His advice is to limit caffeine to no more than the equivalent of two cups of coffee a day.
And, while most women would probably get away with eating cold meat and improperly cooked food, it is not worth taking the risk of losing a baby.
"I am sure Oster is correct in her interpretation of the statistical risk, but is avoiding certain things in pregnancy such a bad thing?"