Is the flu shot safe and recommended for pregnant women?

Influenza Vaccination During Pregnancy

The influenza vaccine is strongly recommended for all pregnant women in any trimester of pregnancy, as it is safe and effective in protecting both the mother and the newborn from severe influenza-related complications. 1, 2

Benefits of Influenza Vaccination During Pregnancy

• Maternal Protection: Pregnant women are at significantly higher risk of severe illness and death from seasonal influenza compared to non-pregnant women 1

  • Risk of hospitalization increases as pregnancy progresses (1.4-fold in weeks 14-20 to 4.7-fold in weeks 37-42) 1
  • During the third trimester, hospitalization rates are comparable to non-pregnant women with high-risk medical conditions 1

• Fetal/Newborn Protection:

  • Reduces risk of late pregnancy loss (adjusted hazard ratio: 10.7) 1
  • Provides passive immunity to infants during their first months of life 2
  • Can prevent reduction in birthweight associated with maternal influenza infection 1

• Preventive Impact: An estimated 1-2 hospitalizations can be prevented for every 1,000 pregnant women vaccinated 1

Safety Profile

• The inactivated influenza vaccine (IIV) is considered safe during any trimester of pregnancy 1, 2, 3
• Multiple studies have demonstrated no adverse fetal effects associated with influenza vaccination during pregnancy 1, 3
• A study of >2,000 pregnant women who received the influenza vaccine showed no adverse effects during pregnancy, infancy, or early childhood 1
• No increased risk of spontaneous abortion has been consistently demonstrated in well-designed studies 4

Vaccination Recommendations

• Timing: Can be administered during any trimester of pregnancy 1, 2, 5

  • Should be given at least two weeks before delivery for optimal antibody transfer 5
  • Some experts historically preferred second trimester administration to avoid coincidental association with first-trimester spontaneous abortions, but this is not based on safety concerns 1

• Type of Vaccine:

  • Recommended: Inactivated influenza vaccine (IIV) - either trivalent or quadrivalent 1, 5
  • Contraindicated: Live attenuated influenza vaccine (LAIV, nasal spray) due to theoretical risk of placental transmission 1, 5

• Priority: The World Health Organization (WHO) and CDC have designated pregnant women as a priority group for influenza vaccination 1, 2

Important Considerations

• No preference for thimerosal-free formulations is indicated for pregnant women 1, 3
• Vaccination coverage rates among pregnant women vary widely (1.7%-95% worldwide, 61.2% in the US) 1
• Healthcare provider recommendation is the most influential factor in vaccination acceptance (75.2% for influenza) 2

Implementation Algorithm

1. Assess immunization status at first prenatal visit
2. Recommend and offer influenza vaccine at any prenatal visit during influenza season
3. Address any concerns about vaccine safety using evidence-based information
4. Administer inactivated influenza vaccine regardless of trimester
5. Document vaccination in medical record and immunization registry
6. If patient declines, continue to offer at subsequent visits

The evidence strongly supports the safety and effectiveness of influenza vaccination during pregnancy, with benefits clearly outweighing any theoretical risks. The medical community has a responsibility to continue recommending and providing influenza vaccinations to pregnant women as a standard of care.