Another possible environmental factor is the use of certain medications during pregnancy, including antidepressants.
In another study also published in the online issue of the journal, researchers found a two-fold risk of autism spectrum disorder among children whose mothers took antidepressants known as selective serotonin reuptake inhibitors (SSRI) during pregnancy, and that the risk was more than three times higher if the mothers took the drugs during early pregnancy, compared to children without the disorder.
SSRIs include widely used antidepressants such as Celexa, Paxil, Prozac and Zoloft.
However, the researchers, from Kaiser Permanente Medical Care Program in Northern California, cautioned that the number of children in the study who were exposed prenatally to SSRIs was low. They say that further studies are needed to validate the results.
About 6.7 percent of women who had a child with autism reported taking anti-depressants during pregnancy, compared to 3.3 percent of controls, or women who did not have a child with autism, researchers said.
Though the risks and benefits taking any medication during pregnancy should be carefully considered, Dr. Natalie Meirowitz, chief of the division of maternal fetal medicine at Long Island Jewish Medical Center in New Hyde Park, advised expectant mothers who suffer from depression not to toss their medications.
That's because depression itself poses a risk to mother and baby. Depressed women may self-medicate with drugs and alcohol, fail to eat right and keep their prenatal appointments, and be unable to care for their baby after delivery, Meirowitz said.
"Pregnancy is a very emotional time for women, and we know that a woman who stops her medication needs a lot of support," she said. "The decision to stop medications has to be made very carefully with the patients' psychiatrist, obstetrician and with their significant other. It shouldn't be made lightly."
The U.S. National Institute of Mental Health has more on autism.
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