Acetaminophen 3rd Trimester and Ductal Closure

July 26, 2018

Written by Clay Smith

Spoon Feed
Acetaminophen (APAP) use during late pregnancy was associated with premature ductus arteriosus closure in these two cases.

Why does this matter?
APAP has long been considered safe for use in pregnancy and is category B.  Prior studies have raised concern for an increased risk of ADHD or asthma related to APAP use in pregnancy.  APAP is used to help with medical closure of patent ductus arteriosus in neonates, which makes one wonder if this could happen in utero. This case series raises that concern.

Inconclusive…but interesting and concerning
This is low quality evidence, to be sure, with a case series of 2 neonates.  But I thought it was worth discussing.  In both cases of premature ductal closure, the women had taken high doses of APAP in late pregnancy.  Infants suffered setbacks but ultimately did well.  Acetaminophen is commonly used during pregnancy without slamming ducti closed all the time, and this series of 2 patients by no means establishes causality.  But it is enough for me to use caution when using APAP in the third trimester.  And when used, it would be best to keep the dose as low and course as brief as possible, certainly well under 3 grams/day, < 3 days.  Even lower doses and duration would be preferable. Ultimately, does this preclude APAP use in pregnancy?  No.  Does it give me pause?  Yes.

Source
Paracetamol/Acetaminophen During Pregnancy Induces Prenatal Ductus Arteriosus Closure.  Pediatrics. 2018 Jun 7. pii: e20174021. doi: 10.1542/peds.2017-4021. [Epub ahead of print]
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Reviewed by Thomas Davis