Pregnancy after 20 weeks: avoid taking ibuprofen and similar painkillers on your own

After 20 weeks of pregnancy, most of the amniotic fluid is produced by the fetus’s kidneys. Taking ibuprofen or similar medications at this stage may harm the fetal kidneys and reduce the amount of amniotic fluid. Some reports received by U.S. authorities describe cases where newborns died after such exposure. Low-dose aspirin prescribed by doctors is not included in this warning.

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In October 2020, the U.S. Food and Drug Administration (FDA) issued a safety warning. Use of nonsteroidal anti-inflammatory drugs after roughly 20 weeks of pregnancy may cause kidney problems in the fetus, leading to low amniotic fluid levels. This warning applies to both prescription and over-the-counter drugs, including aspirin, ibuprofen, naproxen, diclofenac and celecoxib. After reviewing adverse event reports up to July 2017, the FDA identified 35 cases of low amniotic fluid or neonatal kidney dysfunction, all with serious outcomes; 5 of these newborns died, each with accompanying kidney failure. In most documented cases, amniotic fluid levels returned to normal within 72 hours to 6 days after medication use stopped. The FDA advises pregnant women not to take these drugs after week 20 unless explicitly directed by a doctor. Low-dose aspirin (81 mg) prescribed for specific pregnancy-related conditions is exempt from this restriction. When pain relief or fever reduction is needed, the FDA recommends using alternatives such as acetaminophen; consult a pharmacist or doctor first.

The FDA notes that many over-the-counter products for colds, flu or insomnia also contain these ingredients, so always check the ingredient list. Previously, U.S. over-the-counter drug labels only warned against use in the final 3 months of pregnancy; this new warning sets the cutoff at around 20 weeks. Low-dose aspirin for preventing preeclampsia is discussed in Section 27, point 5 (“Low-dose aspirin”). The grade B rating reflects that these figures come from adverse event reports; we have no data on how many women took these drugs without experiencing any issues. The “moderate” benefit rating reflects the seriousness of these outcomes, even though they occur infrequently.

U.S. Food and Drug Administration (2020-10-15). FDA recommends avoiding use of NSAIDs in pregnancy at 20 weeks or later because they can result in low amniotic fluid. Drug Safety Communication. https://www.fda.gov/drugs/drug-safety-and-availability/fda-recommends-avoiding-use-nsaids-pregnancy-20-weeks-or-later-because-they-can-result-low-amniotic