Can pregnant women receive the influenza (flu) vaccine?

Influenza Vaccination in Pregnancy

Yes, pregnant women should receive the inactivated influenza vaccine during any trimester of pregnancy, and this is strongly recommended by all major medical organizations. 1

Why Vaccination is Critical

Pregnant women face substantially elevated risks from influenza infection:

• Risk of hospitalization increases progressively throughout pregnancy, rising from 1.4-fold at 14-20 weeks gestation to 4.7-fold at 37-42 weeks compared to postpartum women 1
• Higher rates of severe complications including pneumonia, ICU admission, and death compared to non-pregnant women 1, 2
• Adverse pregnancy outcomes including late pregnancy loss (adjusted hazard ratio 10.7), preterm birth, low birthweight, and small-for-gestational-age infants 1

Vaccine Safety Profile

The safety evidence is robust and reassuring:

• No association with congenital malformations in any trimester, including first trimester, based on a 5-year cohort of over 10,000 women and a meta-analysis of 15 studies 1
• No increased risk of spontaneous abortion, with follow-up studies confirming safety after initial concerns were not replicated 1
• Can be administered safely during any trimester without restriction 1, 2

Dual Protection: Mother and Infant

Maternal vaccination provides critical protection for both populations:

• Infants born to vaccinated mothers have up to 72% risk reduction for laboratory-confirmed influenza hospitalization in their first 6 months of life 1, 3
• Protection occurs through transplacental antibody transfer during pregnancy (IgG antibodies) 1, 3
• Additional protection through breastfeeding with sustained high levels of influenza-specific IgA antibodies in breast milk for up to 6 months postpartum 1, 3
• Infants under 6 months cannot receive influenza vaccine themselves, making maternal vaccination their only direct protection 1

Specific Vaccine Recommendations

Use inactivated influenza vaccine (IIV) only:

• Any licensed, age-appropriate IIV3, IIV4, RIV3, or RIV4 can be used during any trimester 1, 2
• Live attenuated influenza vaccine (LAIV) is absolutely contraindicated during pregnancy due to theoretical risk of placental viral transmission 1
• LAIV is safe postpartum and during breastfeeding 1

Optimal Timing

Vaccinate as soon as vaccine becomes available, ideally by end of October:

• Do not delay vaccination to a specific trimester - any trimester is appropriate 1
• Continue vaccination throughout influenza season (October through May in the US) even if influenza is already circulating 1
• Women in third trimester during July-August can be vaccinated early to protect infants in first months after birth 3

Common Pitfalls to Avoid

Do not withhold vaccination based on:

• First trimester concerns - extensive safety data supports vaccination in all trimesters 1
• Egg allergy - severe allergic reactions to egg-based influenza vaccines are extremely rare, and egg allergy is not a contraindication 1
• Minor illnesses or upper respiratory symptoms - these are not contraindications 1
• Breastfeeding status - vaccination is safe and beneficial during breastfeeding 1, 3

Provider Role is Critical

Healthcare provider recommendation is the single most important factor:

• Women offered vaccination by their provider have 71% uptake versus only 14% among those not offered 4
• Obstetricians should stock and administer vaccine in their offices whenever possible 2
• If unable to provide vaccine, refer immediately to pharmacy or community vaccination center 2
• Despite recommendations, only 41-52% of pregnant women receive influenza vaccine, representing a major missed opportunity 1, 4, 5