Women who take antidepressants during pregnancy do not appear to be at greater risk of giving birth to children with congenital heart defects compared to women who are not exposed to the drugs, according to new research from UCL.

The study, which analysed data from over 200,000 pairs of women and children in the UK between 1990 and 2011, showed that other characteristics, including diabetes, a body mass index of more than 30 and a history of alcohol and drug use did pose a greater risk of having a baby with congenital heart problems. These factors were also found to be more prevalent among women who had received antidepressants.

Lead author, Dr Irene Petersen (UCL Department of Primary Care and Population), said: "Women often receive conflicting messages on whether they should continue taking antidepressants during pregnancy and many women may discontinue antidepressants in pregnancy because they fear adverse effects on their unborn child.

"Our research adds to the ongoing debate on whether these drugs cause congenital heart anomalies, and we have found no evidence to any such effect. However, health care professionals should counsel women on other risks contributing to congenital heart anomalies in children such as age, weight, diabetes, alcohol problems and illicit drug use."

The findings are particularly significant as some previous studies have suggested there is a link between SSRIs (the most commonly prescribed antidepressants in pregnancy) and congenital heart anomalies. However, often these studies have not taken other risk factors into account which can have a damaging impact on children's health.

The study compared 4 cohorts of women with and without different antidepressant exposures before and during pregnancy. 5,154 women were receiving SSRIs before pregnancy, 2,776 were receiving SSRIs during pregnancy, 992 were receiving other antidepressants during pregnancy and 200,213 were receiving no antidepressants before or during pregnancy. The results showed the risk of having a child with a recorded congenital heart anomaly was less than 1% across all four cohorts. This risk was higher among older women and those who were obese and more than doubled among women with diabetes or drug and alcohol problems.

The findings showed that 20% of women who had not been prescribed antidepressants had health records indicating that they were smokers compared to 35% of the women who had been prescribed SSRIs and although the number of individuals with entries of alcohol problems and illicit drug use was small, such use was more than 10 times more common among women who continued antidepressants in pregnancy.

Previous studies from Dr Petersen's research team have shown that four out of five women stop using antidepressants when they become pregnant. She explained: "We know from a US study that up to 70 percent of pregnant women, who stop an antidepressant, have a recurrence of depression, which also can have major consequences. So it is important to consider both the pros and cons before women stop taking antidepressants during pregnancy."

The study will be published in the Journal of Clinical Psychiatry.