The final search strategy, modified for each database, resulted in a total of 1343 citations that were uploaded to Covidence. After 199 duplicate citations were removed, a reminder of 1144 citations were screened by title and abstract, resulting in 125 studies being eligible for full text review. A final count of 44 studies were extracted for analysis. The detailed search process is illustrated via the PRISMA chart in Fig. 1.

Among the 44 included studies, 38 were quantitative, one was qualitative, and five were mixed methods. A total of 40,934 participants were included from 39 different countries: thirteen countries in Europe, six countries in the Western Pacific Region, eight countries in the Americas, five countries in Africa, four counties in the Eastern Mediterranean region, and three countries in South-East Asia (Table 1).

Among extracted articles, reasons given by pregnant persons for COVID-19 vaccine hesitancy were collected and sorted into themes based on the 5Cs framework. All five categories of this framework were represented: Confidence, Complacency, Constraints, Collective Responsibility, and Calculation (Table 2, Fig. 2).

Number of studies in each category of the 5C framework stratified by vaccine hesitancy and vaccine acceptance.

In the context of vaccine hesitancy, a lack of confidence is defined as a lack of trust in vaccines, vaccine delivery systems, and political figures overseeing vaccination programs. A lack of confidence in the vaccination was a major theme of vaccine hesitancy found among all 44 extracted articles14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57. Among all 44 studies, concerns regarding the safety of the vaccine, both for themselves and their fetuses, were brought up by pregnant persons. Across 37 articles, pregnant participants feared adverse effects and health complications after getting vaccinated, especially for pregnant persons with chronic medical conditions14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,31,32,33,34,35,36,37,38,40,42,43,44,45,49,50,52,53,54,55,56,57. Specific concerns mentioned by pregnant persons included infertility15,21,23,28,29,30,31, postpartum hemorrhage16, and death31. In two studies in the United States, pregnant persons were concerned that harmful ingredients were present in the vaccines14,23. Meanwhile, among 33 studies, pregnant participants feared that the vaccine would not be safe for their fetus14,15,16,17,18,19,20,21,22,23,24,25,26,28,29,30,31,32,33,34,35,36,37,38,39,41,46,47,53,54,55,56,57. Specific concerns mentioned by pregnant persons included fear of congenital malformations, hearing and visual impairments, preterm birth, and miscarriages14,16. Pregnant persons in 5 studies did indicate that they may feel comfortable getting vaccinated post-pregnant or post-breastfeeding22,29,30,40,41.

Pregnant persons expressed mistrust in the vaccine due to the lack of data about safety and efficacy, including the lack of representation of pregnant persons in clinical trials, a sentiment seen among 34 studies15,16,17,18,19,20,22,