Doctors have long suspected that there is some causal relationship between a pregnant woman's use of a class of antidepressants known as SSRIs (selective serotonin reuptake inhibitors) and the increased risk of birth defects.
While the authors of the study said they found an increased risk, it is still fairly low. They suggest a need for additional studies “to enable women and their healthcare providers to make more informed decisions about treatment.”
SSRIs include many widely-used antidepressant drugs, including Prozac, Zoloft, and Paxil.
This isn't exactly a new issue, and numerous studies over the years have reached conflicting conclusions. That's led to a lot of uncertainty around the safety of antidepressant use during pregnancy.
A team of researchers, led by the Centers for Disease Control and Prevention, specifically looked at the types of birth defects previously reported by women who had been taking SSRIs. The researchers combined results from independent published analyses with data from the US National Birth Defects Prevention Study (NBDPS) to give a more balanced estimate of any association between individual SSRIs and birth defects.
The study was a major one, analyzing 17,952 mothers of infants with birth defects and 9,857 mothers of infants without birth defects, born between 1997 and 2009. Drugs under review included the brand names Celexa, Lexapro, Prozac, Paxil, and Zoloft.
To be included, a woman had to take one of these drugs at least once in the time period between one month before conception and the third month of pregnancy. Women who reported taking antidepressants other than SSRIs or reporting pre-existing diabetes were excluded.
No link with Zoloft
Zoloft was the most commonly used SSRI, but none of the five previously reported associations between Zoloft and birth defects were confirmed. The authors say that's good news because about 40% of women reporting use of an SSRI in early pregnancy used that drug.
For nine other previously reported associations between maternal SSRI use and birth defects in infants, findings were also consistent with no association.
Where a link did emerge was between the use of Prozac and two birth defects - heart wall defects and irregular skull shape. Five birth defects associated with Paxil were also observed. They included heart defects, problems with brain and skull formation, and abdominal wall defects.
The main takeaway, the authors say, is there is some reassurance that some SSRIs have no association with birth defects, but that others carry a concern, albeit a small one.
“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,” the authors concluded.
For example the risk of a particular birth defect might rise from 2 per 10,000 to 7 per 10,000. The researchers say physicians should take their findings into account when making treatment decisions.