Thousands of women who take anti-depressants during pregnancy are putting their unborn babies at risk, researchers warn.
The widely-prescribed pills drastically raise the odds of miscarriages, premature birth, autism and life-threatening high blood pressure, according to the Harvard experts.
They suspect drug companies are trying to play down the risks as anti-depressants are so lucrative to them.
They focused on the complications linked to a group of drugs called selective serotonin reuptake inhibitors (SSRIs), which include Prozac and Seroxat. It was found they increase the risk of miscarriage by 17 per cent and more than double the likelihood of pre-eclampsia - high blood pressure during pregnancy - which can be fatal.
They also double the chances of the baby being born premature, or developing autism and the babies are more likely to suffer from heart defects and problems with their bowels.
SSRIs treat depression by boosting the level of the 'happy hormone' serotonin in the brain.
But the researchers believe serotonin is also getting into the womb and harming the development of the foetus's brain, lungs, heart and digestive system.
Dr Adam Urato, assistant professor of obstetrics and gynaecology at Tufts University School of Medicine, in Boston, who was involved in the study, admitted he was "very concerned".
"We are witnessing a large-scale human experiment.
"Never before have we chemically altered human foetal development on such a large scale. And my concern is why I am trying to get the word out to patients, health care providers, and the public."
Dr Alice Domar, assistant professor in obstetrics, gynaecology and reproductive biology at Harvard Medical School, said there was little evidence the pills effectively treated depression. Doctors were handing out prescriptions for the drugs even though depression could be far better treated through exercise, talking therapies and yoga, she said.
"These are probably not particularly safe medicines to take during pregnancy.
"We're not saying that every pregnant woman should go off her medication. Obviously you don't want a pregnant woman to attempt suicide."
The researchers, who presented their findings to the annual conference of the American Society for Reproductive Medicine in San Diego, California, have analysed more than 100 existing studies looking at the risks of SSRIs.
Their findings are due to be published in the respected journal Human Reproduction.
A spokesman for the Association of the British Pharmaceutical Industry said: "Clinical decisions about the treatment of depression are complex and must be made by clinicians in consultation with individual patients, regardless of whether or not they are pregnant."
- DAILY MAIL