What are the recommended treatments for a pregnant woman with influenza (flu)?

Treatment of Influenza in Pregnant Women

Pregnant women with confirmed or suspected influenza should be treated immediately with oseltamivir 75 mg orally twice daily for 5 days, regardless of trimester or illness duration, because pregnancy significantly increases the risk of severe complications, hospitalization, and maternal mortality from influenza. 1

Why Aggressive Treatment is Critical

Pregnant women face dramatically elevated risks from influenza infection:

• Hospitalization risk increases progressively throughout pregnancy, from 1.4-fold at 14-20 weeks to 4.7-fold at 37-42 weeks gestation compared to non-pregnant women 1
• Maternal mortality risk is substantially higher, with pregnant women showing disproportionately high death rates during influenza pandemics 2
• Fetal complications include increased odds of congenital anomalies, stillbirth, late pregnancy loss (adjusted hazard ratio 10.7), preterm delivery, low birth weight, and small-for-gestational-age infants 2, 1

First-Line Antiviral Treatment

Oseltamivir is the treatment of choice:

• Dosing: 75 mg orally twice daily for 5 days (standard adult dosing) 1
• Timing: Start immediately upon suspicion of influenza—do not wait for laboratory confirmation 1
• Safety: Extensive use during pregnancy has demonstrated safety across all trimesters 1
• Common side effects: Nausea (10%) and vomiting (9%), which are generally mild 1

Alternative option if oseltamivir is contraindicated:

• Zanamivir: 10 mg (two 5 mg inhalations) twice daily for 5 days 1

Supportive Care

Symptomatic management includes:

• Adequate hydration and rest as essential supportive measures 1
• Acetaminophen for fever and pain: Generally considered safe during any trimester when used at the lowest effective dose for the shortest duration 3, though emerging evidence suggests limiting use to conditions that might harm the fetus (severe pain or high fever) 4

Warning Signs Requiring Urgent Evaluation

Monitor for these complications:

• Difficulty breathing or chest pain
• Persistent high fever despite treatment
• Decreased fetal movement
• Signs of preterm labor 1

Prevention: The Most Important Intervention

All pregnant women should receive inactivated influenza vaccine:

• Timing: During any trimester, including the first trimester, as soon as vaccine becomes available (ideally by end of October) 5, 1
• Vaccine type: Any licensed inactivated influenza vaccine (IIV3 or IIV4) or recombinant vaccine (RIV3 or RIV4) 1
• Contraindication: Live attenuated influenza vaccine (LAIV, intranasal) is contraindicated during pregnancy 2, 5, 1

Vaccination provides dual protection:

• Maternal protection: Reduces risk of severe influenza illness, hospitalization, and complications 2, 5
• Infant protection: Infants born to vaccinated mothers have up to 72% risk reduction for laboratory-confirmed influenza hospitalization in the first months of life through transplacental antibody transfer 5, 1

Common Pitfalls to Avoid

• Do not delay antiviral treatment waiting for laboratory confirmation—clinical suspicion is sufficient to initiate therapy 1
• Do not withhold treatment based on trimester—oseltamivir is safe throughout pregnancy and the risks of untreated influenza far outweigh any theoretical medication concerns 1
• Do not use live attenuated influenza vaccine during pregnancy (though it can be used postpartum) 2, 5, 1
• Do not delay vaccination if planning pregnancy or in early pregnancy—vaccination during the first trimester is safe and not associated with congenital malformations 5