Stockholm, Sweden—Women who are pregnant are among the groups at high risk of influenza complications and should receive antiviral therapy, state guidelines from the CDC, as well as its European counterparts.

A study published by The BMJ explores the question of how the drugs, which are chemically related antiviral medications known as neuraminidase inhibitors that have activity against both influenza A and B viruses, affect newborn babies.  

The results? No increased risks to newborn babies were detected after their mothers took drugs to prevent or treat influenza during pregnancy.

The study, by researchers from the Karolinska Institute Hospital in Stockholm, is touted as the largest study to assess potential risks of taking neuraminidase inhibitors during pregnancy.

In the U.S., three influenza antiviral medications approved by the FDA are recommended for use during the 2016-2017 influenza season:
• Oral oseltamivir (available as a generic version or under the trade name Tamiflu),
• Inhaled zanamivir (trade name Relenza), and
• Intravenous peramivir (trade name Rapivab).

Conducted from 2008 to 2010, the study involved almost 6,000 women who were prescribed any of two neuraminidase inhibitors, oseltamivir or zanamivir, during pregnancy—and almost 700,000 women who did not receive prescriptions during a pregnancy in the same time period.

After taking into account several health-related factors such as age, smoking and use of other medications, results indicate no increased risks of adverse outcomes including low birth weight, low Apgar score, preterm birth, stillbirth, or birth defects.

Limitations of the study, researchers note, are that it did not assess risks of adverse outcomes before 22 weeks of pregnancy, and some women could have filled a prescription without taking the drug.

“In this large multinational register study, we found no increased risk of adverse neonatal outcomes or congenital malformations associated with exposure to neuraminidase inhibitors during pregnancy,” study authors conclude. “Our results support previously reported findings that the use of neuraminidase inhibitors is not associated with increased risks of adverse fetal or neonatal outcomes.”

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