[Self-reported maternal adverse events of covid-19 vaccination during pregnancy].

Objective: To describe the self-reported maternal adverse events (AEs) of covid-19 vaccination during pregnancy.

Design: The Dutch Pregnancy Drug Register ("Moeders van Morgen"), is a prospective cohort study among pregnant women in the Netherlands.

Method: Using online questionnaires, women reported whether they received a covid-19 vaccination and the self-perceived AEs after vaccination. We included women who received their first covid-19 vaccination during pregnancy. We assessed the maternal AEs by vaccine dose, type of vaccine (BioNTech/Pfizer, Moderna, AstraZeneca, and Janssen) and moment of vaccination in pregnancy.

Results: 4348 women received their first covid-19 vaccination during pregnancy and were included. Of these, 2787 women also reported a second dose during pregnancy. After the first dose, AEs were less often reported for BioNTech/Pfizer (56% ≥1 AE), compared to Moderna (68% ≥1 AE) or AstraZeneca (87% ≥1 AE). After the second dose, AEs were less often reported for BioNTech/Pfizer (44% ≥1 AE) compared to Moderna (76% ≥1 AE). Injection site reactions, myalgia and fatigue were reported most frequently. There was large variation in the percentage reporting pyrexia/fever between the different vaccines (3%, 22%, and 10% after the second dose of BioNTech/Pfizer, Moderna, and Astrazeneca respectively). There were no major differences in the rates of AEs between vaccination in the first, second, or third trimester.

Conclusion: The adverse event profile among women who were vaccinated against covid-19 during pregnancy do not indicate any safety concerns. Considering the reported maternal AEs, the BioNTech/Pfizer vaccine seems best for vaccination during pregnancy.