WASHINGTON: Morning sickness is an all-too-common side effect of pregnancy, and a new study out Wednesday said a medication used to treat the most serious cases is safe for fetuses.

The trials of pregnancy-induced nausea - and its more devastating cousin, hyperemesis gravidarum - have made headlines lately, with celebrity moms and moms-to-be from Kate Middleton to Kate Winslet publicly suffering through it.

More than half of pregnant women report symptoms and between 10 and 15 per cent need drug treatment, according to the authors whose study was published in the New England Journal of Medicine.

While there was no approved treatment, the researchers said a medication approved to treat the nausea from cancer drugs called Zofran, or ondansetron, became doctors' go-to weapon against severe cases of nausea and vomiting in pregnancy.

But it had “not been well studied” in terms of fetal health, they added.

The researchers examined data from more than 600,000 pregnancies in Denmark, about a fifth of whom had taken Zofran, and found no indication of any major problems at birth that could be linked to the drug.

The researchers compared rates of miscarriage, still birth, premature delivery, low birth weights and infants who were small for their gestational age.

“Ondansetron taken during pregnancy was not associated with a significantly increased risk of adverse fetal outcomes,” said the authors.

The study was funded by the Danish Medical Research Council.