How baby’s first shot determines the development of maternal attitudes towards vaccination

•Knowledge about the development of maternal attitudes towards vaccination is lacking.•This longitudinal study assessed development of attitudes from pregnancy to early childhood.•Mothers become more vaccine-skeptical when first vaccination experience with the baby is negative.•Mothers have more concerns about vaccination-related risks when the first experience was negative. The attitude towards vaccination is a major determinant of vaccination behavior; this also includes parents’ attitudes towards the immunization of their child. Negative attitudes have been associated with vaccine hesitancy and outbreaks of infectious diseases throughout the globe. This study aimed to assess how and why attitudes become more pro-vaccine or vaccine-skeptical over time, and which sources are especially influential in this process. Prospective cohort study with measurements at time of recruitment during pregnancy and at +3, +6 and +14 months after childbirth with cross-sectional control groups. In total, 351 women entered the longitudinal analyses, while 204, 215 and 173 women were recruited in the cross-sectional control groups, respectively. Inclusion criteria were: (i) being at least 18 years of age, (ii) pregnant, (iii) primigravida, and (iv) living in Germany. During pregnancy mothers reported rather positive prior experiences with vaccinations. However, their judgment turned significantly more negative after the first vaccination experience with their child. Mixed-effects models showed that these changes were significantly related to increased risk perceptions and concerns about vaccination, which then had a negative impact on the vaccination attitude. In contrast, gaining more vaccine-related knowledge over time positively influenced attitude formation. During the first year of their child’s life maternal attitudes towards vaccination are formed and guide future decisions whether to vaccinate or not vaccinate a child. Strategies should be implemented that improve mothers’ experiences when their newborn is vaccinated to prevent the development of vaccine hesitancy.