Use of a type of anti-depressant medication during pregnancy may increase the risk of a stillborn baby, research suggests.
Babies may be affected by drugs in the womb
A Canadian study of almost 5,000 mothers found those who used SSRIs were also more likely to have premature and low birth weight babies.
However experts said women should not stop taking medication without expert advice.
The study is published in the American Journal of Obstetrics and Gynaecology.
The researchers, from the University of Ottawa, compared the health of babies born to 972 women taking SSRI anti-depressants with that of babies born to mothers who did not use anti-depressants.
SSRIs, or selective serotonin reuptake inhibitors work by increasing levels of the mood chemical serotonin in the brain. They include Prozac.
The researchers found women using the drugs were twice as likely to have a stillbirth. They were also almost twice as likely to have a low birth weight baby.
Almost 20% of women who used SSRIs gave birth prematurely, compared to 12% of those who did not use the drugs.
Babies born to women using SSRIs were also more likely to have seizures.
Benefits and risks
The researchers said women should be fully briefed about the potential risk of SSRIs before taking a decision about whether or not to use them.
Charlotte Davies, of Tommy's, the baby charity said pregnant women could opt for other types of anti-depressant medication.
She said: "Whilst this study has found a correlation between SSRIs and pregnancy complications, it has in no way confirmed a clear causal effect between the two, so pregnant women should continue taking their medication as normal.
"Left untreated, the physical and psychological effects of depression can lead to problems during pregnancy.
"Sufferers of depression are far more likely to smoke, as well as lose their appetites and in extreme cases are more likely to attempt suicide, which can all have devastating effects on mother and baby."
Previous research has also raised doubts about the safety of using SSRIs while pregnant.
Last year Danish and US scientists found use of the drugs in the first three months of pregnancy was linked to a 40% increased risk of birth defects such as cleft palate.
That research also suggested that use of SSRIs in pregnancy raised the risk of a premature birth.
In a separate study, Spanish research found that babies whose mothers used SSRIs are at risk of being born with withdrawal symptoms.
The Medicines and Healthcare products Regulatory Agency has warned doctors not to prescribe most SSRI drugs, apart from Prozac, to children.
This followed evidence that use of the drugs in young people might increase the risk of suicidal behaviour.
A spokesman for Eli Lilly, which manufactures, Prozac said the company had never promoted the use of the drug for pregnant or nursing mothers.