Use of a type of anti-depressant medication during pregnancy may increase the risk of birth defects such as cleft palate, research suggests.
Babies may be affected by drugs in the womb
Danish and US scientists found use of SSRIs in the first three months of pregnancy was linked to a 40% increased risk - but the results are preliminary.
Cardiac defects appeared to be 60% more likely when the women used SSRIs.
But the researchers stress the results, featured in Pulse magazine, do not mean women should stop taking the drugs.
The findings were presented an International Society for Pharmacoepidemiology conference.
SSRIs, or Selective Serotonin Re-uptake Inhibitors, include commonly prescribed drugs such as Prozac and Seroxat. They work by boosting levels of the mood chemical serotonin in the brain.
Their use during pregnancy was linked to withdrawal symptoms in newborn babies in a study published in The Lancet earlier this year.
And doctors have been told not to prescribe them to children because of an increased risk of suicide.
In the latest study, focusing on 1,054 women who took SSRIs during pregnancy, scientists also found that use of the drugs late in pregnacy was associated with a 40% increased risk of premature birth.
And a second study of 377 cases of persistent pulmonary hypertension in babies found SSRI use late in pregnancy was linked a 5.5-fold increased risk.
Lead researcher Professor Henrik Toft Sorensen told the BBC News website that the study was still in its early stages, and it was unclear whether SSRI use caused problems, or whether some other factor, such as an unhealthy diet, might be to blame.
"I do not think people should take any public health action based on this data at this stage," he said.
"And people should remember that the risk is still very low."
The Medicines and Healthcare products Regulatory Agency issued a statement, saying: "Previous studies have shown differing results, some showing no difference in birth defects in women taking antidepressants to the average population rate.
"The MHRA is carefully considering these data with European colleagues and will issue advice as necessary.
"As with all medicines, antidepressants should only be taken in pregnancy if the expected benefit to the mother is thought to be greater than the risk to the foetus, and all drugs should be avoided in the first trimester if possible.
"People taking antidepressants should not stop them without seeking medical advice."