Some selective serotonin reuptake inhibitors taken during early pregnancy may be associated with an increased risk of birth defects, according to researchers in North America.
The study authors stressed that the absolute risks for these birth defects are still low and called for further research “to enable women and their healthcare providers to make more informed decisions about treatment”.
They noted that the association between use of antidepressants, especially SSRIs, during pregnancy and birth defects in the infants has been the topic of much discussion in recent years.
“Continued scrutiny of the association between SSRIs and birth defects is warranted”
Studies have reached conflicting conclusions, leading to uncertainty around the safety of antidepressant use during pregnancy, they said.
The researchers, from the US and Canada, combined results from independent published analyses with data from the US National Birth Defects Prevention Study. Their analysis included 17,952 mothers of infants with birth defects and 9,857 mothers of infants without birth defects, born between 1997 and 2009.
Use of the SSRI drugs citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac), paroxetine (Paxil), or sertraline (Zoloft) at least once in the period from one month before conception to the third month of pregnancy was recorded.
Sertraline was the most commonly used SSRI, but none of the five previously reported associations between sertraline and birth defects were confirmed. This is reassuring, said the study authors, as about 40% of women reporting use of an SSRI in early pregnancy used sertraline.
For nine other previously reported associations between maternal SSRI use and birth defects in infants, findings were also consistent with no association.
“The increase in the absolute risks, if the associations are causal, is small”
However, two previously reported birth defects associated with fluoxetine treatment were observed – heart wall defects and irregular skull shape (craniosynostosis).
Five previously reported birth defects associated with paroxetine treatment were also seen. These included heart defects, problems with brain and skull formation (anencephaly) and abdominal wall defects.
The data suggests that some birth defects occur more frequently among the infants of women treated with paroxetine or fluoxetine in early pregnancy, said the researchers.
But they stated: “Although our analysis strongly supports the validity of the associations that were observed, the increase in the absolute risks, if the associations are causal, is small.”
For example the absolute risks in the children of women who are treated with paroxetine early in pregnancy would increase for anencephaly from two per 10,000 to seven per 10,000, and for one of the heart defects from 10 per 10,000 to 24 per 10,000.
The study authors said continued scrutiny of the association between SSRIs and birth defects was “warranted”.
“Additional studies of specific SSRI treatments during pregnancy are needed to enable women and their healthcare providers to make more informed decisions about treatment,” they said in the British Medical Journal.
“Meanwhile, the current analysis provides guidance to the safest treatment options during early pregnancy to minimise the risk of major birth defects, while providing adequate treatment of maternal depression,” they added.