(NEW YORK) — Pregnant women should avoid a group of over-the-counter pain relievers, including Advil and Aleve, for one month longer than previously advised, according to a new warning from the U.S. Food and Drug Administration (FDA).

Those pain relievers should now be avoided by pregnant women for the last four months of pregnancy, instead of the last three, according to the FDA’s new guidance.

Use of nonsteroidal anti-inflammatory drugs (NSAIDs) by women at the midway point of their pregnancy, around 20 weeks or later, may cause what the FDA describes as “rare but serious kidney problems” for the fetus, as well as low levels of amniotic fluid which can cause further complications.

The types of pain relievers that pregnant women should avoid in the second half of their pregnancy include medicines like aspirin, ibuprofen, naproxen, diclofenac and celecoxib, according to the FDA.

The agency said it plans to update the labels of over-the-counter pain relievers to indicate that pregnant women should avoid using them during the last four months of pregnancy.

“In obstetrics, we have known that there should be caution when using these medications in pregnancy for decades,” said Dr. Jennifer Ashton, a board-certified OBGYN and ABC News chief medical correspondent. “This is really an FDA awareness alert for pregnant women themselves and other healthcare professionals.”

One of the most common calls that obstetricians and midwives get from pregnant patients is whether or not it is safe to use a pain reliever for pain or fever relief, according to Ashton.

“Acetaminophen, Tylenol [are] generally safe,” she said. “Other than that you absolutely want to check with your obstetrician or midwife.”

Ashton also noted that obstetricians like herself do sometimes use NSAIDs on women in their second and third trimesters to help treat preterm labor.

“It’s all about weighing the benefits versus the risks and using it under medical supervision,” she explained.

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