Feb. 2, 2004 — Babies born to mothers taking one of the most widely prescribed types of antidepressants have higher-than-normal amounts of tremors and other subtle behavioral problems shortly after birth, new research shows.

It is not clear if these behavioral differences persist after the first few days of life. But investigators say they hope the findings will lead to a more thorough look at the safety of taking selective serotonin reuptake inhibitor (SSRI) antidepressants such as Prozac, Celexa, or Zoloft during pregnancy.

Researcher Philip Sanford Zeskind, PhD, says they should also be considered when moms-to-be and their physicians weigh the pros and cons of using the drugs to treat depression.

“Right now the thinking is that there are no effects on the baby when a mom takes these antidepressants during pregnancy,” researcher Philip Sanford Zeskind, PhD, tells WebMD. “But I don’t think we can conclude that at this point.”

Subtle Differences

With the growing awareness of the dangers of untreated depression during pregnancy and following childbirth, SSRI antidepressants are increasingly being prescribed to new moms and moms-to-be.

Studies looking at the effects of SSRI’s taken during pregnancy have been inconclusive, — and for this reason the American Academy of Pediatrics has stated that drawing a conclusion from these studies are based on insufficient amounts information and that more research is needed.

But Zeskind and Carolinas Medical Center colleague Laura Stephens wanted to find out if SSRI use could be linked to less easily measurable postnatal outcomes.

To do this they conducted a battery of tests on day-old infants born to mothers who did and did not take the antidepressants during pregnancy.

The 17 SSRI-exposed infants in the study were found to have a higher incidence of tremors and they exhibited more movement activity during an observation period of sleep than the 17 nonexposed newborns. In addition, the exposed babies exhibited a sleeping pattern that is typically seen among high-risk infants. Instead of progressing through different sleep states, they appeared locked in the deep REM sleep stage, Zeskind says.

When heart rates were monitored, SSRI-exposed babies were more likely to have abnormal heart rhythms than babies born to mothers who did not take antidepressants. The study is published in the Feb. 2 issue of the journal Pediatrics.

Serotonin Toxicity

The researchers speculate that the abnormal amounts of tremors and movements in the newborns may be symptoms caused by withdrawal from the drugs or by overexposure to serotonin while in the womb. SSRIs work by increasing a chemical called serotonin in certain portions in the brain. The increase in the chemical production helps depression and other mood disorders. Yet SSRIs readily cross the placenta and babies are exposed to high levels of serotonin during development.

“That may be great for the mom, but it leaves a lot of serotonin floating around her system so the baby could be swimming in it,” Zeskind says. “There is reason to believe that the differences we saw could be due to serotonin toxicity.”

The SSRI-exposed infant would be described as tremulous, motorically erratic, underaroused, and in an unchanging REM state writes the authors.

Stanford University pediatrics professor William Benitz, MD, tells WebMD there is still no reason to believe that SSRI exposure in the womb is associated with lasting problems. But he adds that the findings should serve as a wake-up call to physicians who consider the issue settled. Benitz serves on the American Academy of Pediatrics committee on drug use.

“This gives us a reason for concern, but we really don’t know if this exposure has an enduring impact,” he says. “What this tells us is that we had better continue to pay attention to this. It doesn’t answer the question, but it keeps it on the table.”