What COVID-19 (Coronavirus Disease 2019) vaccine is safe for use in pregnancy?

COVID-19 Vaccination in Pregnancy

The mRNA COVID-19 vaccines (Pfizer-BioNTech and Moderna) are safe and recommended for use during pregnancy at any gestational age. 1, 2

Primary Recommendation

Pregnant women should receive COVID-19 vaccination regardless of trimester, as the benefits of protection against severe disease substantially outweigh any theoretical risks. 1, 2 The CDC recommends COVID-19 vaccination for all people aged 12 years and older, including those who are pregnant, breastfeeding, trying to get pregnant, or might become pregnant in the future. 1, 2

Evidence Supporting Safety

• Real-world safety data from 90,000 pregnant women collected through the V-safe COVID-19 vaccine pregnancy registry identified no safety signals. 1, 2
• A systematic review of 46,264 pregnancies vaccinated with mRNA vaccines showed reassuring outcomes: only 0.03% stillbirths and 3.68% preterm births, with average birthweight of 3,452g. 3
• The spontaneous abortion rate among women vaccinated in the first trimester was 6.5%, which is within the expected baseline rate of 10%. 4
• Local adverse effects (injection site pain, swelling, redness) occurred in 32%, 5%, and 1% respectively, while systemic effects (fatigue, headache, muscle pain) were transient and similar to non-pregnant populations. 3

Why Vaccination is Critical in Pregnancy

Pregnant women face substantially higher risks from COVID-19 infection compared to vaccination risks. 2 COVID-19 infection during pregnancy is associated with:

• 1.57-fold increased risk of preeclampsia or eclampsia 1, 2
• 2.17-fold increased risk of preterm delivery 1, 2
• 2.21-fold increased risk of fetal death 1, 2
• 2-3 fold higher rates of ICU admission, invasive ventilation, and maternal mortality compared to non-pregnant women 2

Approved Vaccines for Pregnancy

Both mRNA vaccines are appropriate:

• Pfizer-BioNTech - Granted full FDA approval August 23,2021 1
• Moderna (mRNA-1237) - Granted FDA Emergency Use Authorization December 18,2020 1

The Janssen (Ad26.COV2.S) vaccine received EUA but mRNA vaccines are preferentially recommended based on more extensive safety data in pregnancy. 1

Timing Considerations

• No specific gestational age restriction exists - vaccination can be administered at any trimester. 1, 2
• Many women historically chose second or third trimester vaccination to avoid theoretical first-trimester concerns during organogenesis, but current evidence supports first-trimester safety. 1, 4
• Third-trimester vaccination may optimize transplacental antibody transfer to the fetus. 5, 6
• Longer intervals between vaccination and delivery are associated with higher fetal IgG antibody levels and better antibody transfer ratios. 6

Additional Benefits

Vaccination provides dual protection for mother and infant:

• Placental transfer of vaccine-specific anti-SARS-CoV-2 IgG antibodies occurs, providing passive immunity to the newborn. 1, 2, 6
• Anti-SARS-CoV-2 IgA and IgG antibodies are detected in breast milk for up to 6 weeks after the first vaccine dose. 1, 2
• Vaccine-related mRNA has not been detected in breast milk, confirming safety for breastfeeding. 5, 2
• Two vaccine doses produce stronger antibody responses and better transplacental transfer compared to single doses. 6

High-Risk Groups Requiring Prioritization

Vaccination is particularly important for pregnant women with: 1, 2

• Healthcare worker status (high exposure risk)
• Age ≥35 years
• Multiple gestation
• Chronic hypertension
• Chronic kidney disease
• Heart conditions (heart failure, coronary artery disease, cardiomyopathies)
• Obesity (BMI ≥30 kg/m²)
• Diabetes mellitus (Type 1 or 2)
• Immunocompromised states
• Autoimmune diseases
• Black or Asian race, or Hispanic ethnicity 2

Contraindications

Absolute contraindications include: 1

• Severe allergic reaction (anaphylaxis) after a previous dose of an mRNA COVID-19 vaccine
• Immediate allergic reaction to any vaccine component, including polyethylene glycol (PEG)
• Immediate allergic reaction to polysorbate (due to potential cross-reactivity with PEG)

Common Pitfalls to Avoid

• Do not delay vaccination waiting for a "safer" trimester - first-trimester vaccination is safe and any trimester is appropriate. 1, 4
• Do not require pregnancy testing before vaccination - WHO explicitly states this is unnecessary. 1
• Do not recommend delaying or terminating pregnancy due to vaccination - WHO confirms vaccination is not a reason for pregnancy delay or termination. 1
• Do not withhold vaccination from breastfeeding mothers - vaccination during lactation is safe and provides additional infant protection through breast milk antibodies. 5, 2

Breastfeeding Considerations

COVID-19 vaccination is safe and recommended during breastfeeding. 5, 2 Experts from the Academy of Breastfeeding Medicine and American College of Obstetricians and Gynecologists agree that vaccination poses minimal to no potential risk to the breastfed infant. 5