Preliminary Findings of mRNA Covid-19 Vaccine Safety in Pregnant Persons

his study presents preliminary safety data from U.S. surveillance systems (v-safe, v-safe pregnancy registry, and VAERS) on mRNA Covid-19 vaccines (Pfizer-BioNTech and Moderna) administered to 35,691 pregnant persons from December 2020 to February 2021. Key findings include:

• Reactogenicity: Pregnant persons reported injection site pain more frequently than nonpregnant women, while systemic reactions (e.g., fever, headache) were less common. Severe reactions were rare (<1% with fever ≥38°C post-dose 1; 8% post-dose 2).

• pregnancy Outcomes: Among 827 completed pregnancies in the registry, 86.1% resulted in live births, 13.9% in pregnancy losses (mostly first trimester spontaneous abortions), and 0.1% in stillbirths. Preterm birth (9.4%) and small size for gestational age (3.2%) rates were comparable to pre-pandemic baselines. No neonatal deaths or congenital anomaly patterns were observed.

• VAERS Reports: Spontaneous abortion was the most frequent pregnancy related adverse event (46 cases), with no safety signals requiring policy changes.

The study concludes that mRNA Covid-19 vaccines do not show obvious safety concerns for pregnant persons or neonates, though longitudinal follow-up is needed, particularly for first trimester vaccination. These findings support current recommendations for vaccine access during pregnancy.

his study presents preliminary safety data from U.S. surveillance systems (v-safe, v-safe pregnancy registry, and VAERS) on mRNA Covid-19 vaccines (Pfizer-BioNTech and Moderna) administered to 35,691 pregnant persons from December 2020 to February 2021. Key findings include:

• Reactogenicity: Pregnant persons reported injection site pain more frequently than nonpregnant women, while systemic reactions (e.g., fever, headache) were less common. Severe reactions were rare (<1% with fever ≥38°C post-dose 1; 8% post-dose 2).

• pregnancy Outcomes: Among 827 completed pregnancies in the registry, 86.1% resulted in live births, 13.9% in pregnancy losses (mostly first trimester spontaneous abortions), and 0.1% in stillbirths. Preterm birth (9.4%) and small size for gestational age (3.2%) rates were comparable to pre-pandemic baselines. No neonatal deaths or congenital anomaly patterns were observed.

• VAERS Reports: Spontaneous abortion was the most frequent pregnancy related adverse event (46 cases), with no safety signals requiring policy changes.

The study concludes that mRNA Covid-19 vaccines do not show obvious safety concerns for pregnant persons or neonates, though longitudinal follow-up is needed, particularly for first trimester vaccination. These findings support current recommendations for vaccine access during pregnancy.