Antidepressants, Pregnancy, and Autism

A possible blockbuster article was published today in JAMA Pediatrics:

Women in a new study who took antidepressants during their second and third trimesters of pregnancy showed an 87 percent increased risk of having a child with an autism spectrum disorder, compared with women who did not take medications for depression while expecting.

The researchers also found that mothers who used a certain class of antidepressants, known as selective serotonin reuptake inhibitors (SSRIs), had more than double the risk of having a child with autism spectrum disorder (ASD).

If this turns out to be true, it might explain a lot. But of course it is only one study, and since autism is not common, the numbers are not really very big:

In the new study, the researchers analyzed data collected from all 145,500 pregnancies that occurred in the Canadian province of Quebec over the 10-year period between January 1998 and December 2009, in which mothers had a full-term pregnancy and gave birth to only one baby. The researchers followed up with the children until age 10; there were 1,054 children who were diagnosed with ASD. . . .

The analysis found that about 4,700 infants, or 3.2 percent of babies, were exposed to antidepressants at some point during their mothers’ pregnancies. Among these babies, 46 developed autism.

So while this is an important finding, and follows up on other hints in this direction, it is not really proof of a causal link. For one thing the evidence is quite strong that women with serious depression are more likely to have autistic children. The size of this effect is disputed; one study showed a 20% increase in autism among the children of women who had ever been treated for depression. If, as some doctors think, the risk rises with more severe depression, and the most severely depressed women are the ones most likely to stay on an SSRI while pregnant, that might explain a lot of the finding. Stay tuned.

When Lisa was pregnant we were told at every turn to avoid antidepressants and many other drugs because there simply wasn't any evidence on whether they were safe or not. Nonetheless, studies have found that many pregnant women do take antidepressants, with different studies returning numbers from 3 to 13% of American mothers. (In the Canadian sample the number is 3.2%.)

As my readers know I am extremely skeptical about the findings of epidemiological studies like this one. On the other hand, something about 21st century life really seems to be making autism more common, and for me the evidence is too iffy for the risk to be worth it.