Factors Affecting the Vaccination Choices of Pregnant Women for Their Children: A Systematic Review of the Literature

"[W]hen developing interventions aimed at increasing vaccine acceptance, an assessment of the most common knowledge gaps and misbeliefs in the target population may be useful for tailoring educational messages."

In recent years, an increase in vaccine hesitancy has led to a decrease in vaccination coverage in several countries. Pregnant women have been recognised as a promising population among whom to develop interventions for the promotion of paediatric vaccinations, considering that pregnancy represents a strategic "teachable moment" for health promotion and behaviour change. This systematic review provides a synthesis of the available evidence on pregnant women's knowledge of and attitudes toward paediatric vaccination, the sources of information most frequently consulted, the frequency of vaccine hesitancy and/or denial, and factors influencing vaccination choices. The aim is to support the development of interventions and promoting further research in this area.

The literature search was performed on the databases Medline, Scopus, and Web of Science in May 2019 and updated in August 2019. A total of 6,277 records were retrieved, and 16 full texts were included in the narrative synthesis. The main features of the included studies are summarised in Table 1 in the paper. All but one were quantitative studies, and 3 had an experimental design. All studies were conducted in western nations, with the exception of one conducted in Japan and one in Malaysia.

Key results:

• Five studies assessed the perceived level of knowledge of childhood vaccinations in their samples of pregnant women, showing that in most cases future mothers were not satisfied with their familiarity with the topic.
• The source of information on paediatric vaccination was investigated in 8 studies. Only one reported healthcare professionals (mainly midwives and general practitioners - GPs) as the most highly accessed resource, while in all other studies the internet or media were the most frequently used. Word of mouth was reported as one of the most common sources of information in all Italian studies.
• Overall, pregnant women believe that vaccines are important for the protection of their children and the community, but attitudes and choices vary depending on the vaccine being considered; the corresponding determinants should therefore be studied in the context of each specific vaccination, say the researchers.
• The percentages of hesitant women, when specifically assessed through the Parent Attitudes About Childhood Vaccines (PACV) questionnaire, ranged in the studies from 8% to 25.5%.
• Various concerns and misunderstandings persist. The most frequently stated reason against the acceptance of vaccination in the studies included were the (potential) side effects of the immunisations. Other factors that hamper acceptance of paediatric immunisation among pregnant women are the frequently reported negative attitudes toward pharmaceutical companies, seen as having an economic interest in promoting vaccination, and a lack of trust in the information provided on vaccination by public authorities and/or healthcare providers.
• Two studies found an association between trust in the health system and a positive attitude toward vaccination.
• Seven studies conducted an inferential analysis to assess the determinants of vaccination choices. Factors most frequently associated with vaccination uptake across studies were the perceived benefits/value of vaccination for the individual and the community and confidence in vaccine safety.

The inferential analyses conducted in some of the studies confirmed that acceptance of paediatric vaccination in this population appears to be mainly driven by issues of complacency (perceived benefits of vaccinations) and confidence (trust in the efficacy and safety of vaccines and in the healthcare system). One suggestion that has been made in this regard is to improve the availability of data on the safety and efficacy of vaccines, and to communicate this evidence data effectively.

Healthcare professionals were shown to play a secondary role (with the internet and the media leading) in informing pregnant women about the risks and benefits of immunisation in nearly all studies. This finding suggests not only the importance of promoting the positive involvement of various media, while carefully monitoring the content of the information provided, but the need to strengthen the role of healthcare professionals - particularly midwives - in delivering information about vaccines. "Specific training strategies would be needed to provide different healthcare providers with the ability to deliver effective communication regarding vaccines safety and efficacy to parents, but also with the aim of counteracting hesitant behavior within health workers themselves.

The data suggest that vaccine hesitancy is a widespread phenomenon in different population strata, and that there might be a need to develop messages to fit different educational and literacy levels. Furthermore, in several studies, first-time mothers showed higher levels of hesitancy and concerns about vaccination than women who already had children, suggesting they should be a priority focus of interventions aimed at increasing confidence in immunisation. "In fact, the first pregnancy represents a particularly propitious moment, since attitudes and beliefs about vaccinations are often not yet fully structured."

In conclusion, "interventions should be tailored based on a context-specific analysis of the determinants of vaccine hesitancy and should also take into account specific vaccine-related factors. Further evidence from non-western and low- or middle-income countries may be needed."