By Tara Haelle
However, the increased risk of the disorder -- known as persistent pulmonary hypertension of the newborn (PPHN) -- is small, and similar to the risk in women with untreated depression.
"Although we cannot exclude the possibility that there might be an increased risk of PPHN associated with SSRI [antidepressant] use late in pregnancy, our study has shown that the absolute risk is small," said lead author Krista Huybrechts. She is an assistant professor of medicine at Harvard Medical School and an epidemiologist at Brigham and Women's Hospital in Boston.
The absolute risk refers to the actual number of infants born with the condition.
"The risk increase, if present, appears much more modest than previous studies have suggested," Huybrechts added.
It's also important to note that this study can only show an association between taking antidepressants in pregnancy and the risk of PPHN; it cannot prove a cause-and-effect relationship.
The findings were published online June 2 in the Journal of the American Medical Association.
A newborn's blood circulation is supposed to change after birth from what it was in the womb, but the circulation in a baby with PPHN does not fully make this transition, according to background information in the study. The condition is life-threatening.
Previous research had suggested that taking antidepressants after the 20th week of pregnancy could significantly increase the risk of PPHN, according to the study authors.
Women with depression commonly take antidepressants, including drugs in a class called selective serotonin reuptake inhibitors, or SSRIs. Common SSRIs include fluoxetine (Prozac), escitalopram (Lexapro), sertraline (Zoloft), paroxetine (Paxil) and citalopram (Celexa).
The researchers followed more than 3.7 million women enrolled in Medicaid from just before their pregnancy through one month postpartum. Among these women, just over 3 percent filled at least one prescription for antidepressants during their third trimester.
Overall, the rate of babies born with PPHN was approximately 21 infants per 10,000 births among women who did not take antidepressants.
Among those who took SSRIs, the rate of the condition was 32 infants per 10,000 births. The rate was slightly lower, 29 children per 10,000 births, for women taking antidepressants other than SSRIs, the study found.
When the researchers compared women with untreated depression to those taking antidepressants, the risk of PPHN didn't differ much between women taking antidepressants and those not taking them.
"A patient should discuss this potential small increased risk as well as all risks and benefits of SSRIs on an individual basis with her doctor," said Dr. David Ghausi, an obstetrician and gynecologist at Los Robles Hospital in Thousand Oaks, Calif. "The physician and patient should determine if the benefits of this medication for the mother outweigh the risks to the fetus."
The fetus of a woman who has untreated depression during pregnancy may also be at higher risk for various conditions, Huybrechts said.
Prenatal depression can also affect a woman's lifestyle and behavior, she added. Depressed women are more likely to smoke more, drink more alcohol and exercise less. And, she said, they're more likely to miss prenatal appointments or skip their prenatal vitamins.
The risks of untreated depression during pregnancy can extend past the baby's birth as well, suggested Dr. Sheryl Ross, an obstetrician and gynecologist at Providence Saint John's Health Center in Santa Monica, Calif.
"Women who go off their normal medications or are untreated during pregnancy are at an increased risk of having a relapse of symptoms, which could potentially be harmful to baby and mother," Ross said. "Untreated mental illness in pregnancy puts women at a much greater risk of postpartum depression," she explained.
"We know there are risks associated with the use of SSRIs, but ultimately it's a conversation about the risks versus the benefits. The studies available show the risk is low compared to the benefits," Ross said.