WASHINGTON - The manufacturers of Prozac and other antidepressants should include prescribing information about an uncommon but life-threatening lung problem that affects babies born to mothers who take the drugs during pregnancy, health officials said Wednesday.

The U.S. Food and Drug Administration said it had asked the companies to add information about the possible risk of the lung disorder, called persistent pulmonary hypertension. Meanwhile, the agency said it is seeking more information about the risk.

Babies with the disorder have high pressure in the blood vessels of their lungs and are not able to get enough oxygen into their bloodstream, the FDA said.

One or two babies per 1,000 in the U.S. develop the disorder shortly after birth. However, infants whose mothers took antidepressants in the second half of pregnancy had six times the expected risk of developing the lung disorder, researchers reported in a study published Feb. 9 in the New England Journal of Medicine.

That report came out days after the Journal of the American Medical Association published a study that illustrated the potential risk of relapsed depression in women who stopped taking prescribed antidepressants during pregnancy.

The two studies worried many women, since they implied there are risks in pregnancy to both continuing on the medications and not.

Women who are pregnant or who are thinking about getting pregnant and take selective serotonin reuptake inhibitors should not stop taking the antidepressants without first talking to a doctor, the FDA said in a public health advisory intended for doctors and patients. The drugs, also called SSRIs, include Prozac, Zoloft, Paxil and Lexapro.

The FDA said it would further update the labels of the drugs as additional information becomes available.