Abstract:

Objective This study aimed to investigate the influenza vaccination coverage among pregnant women in Shanghai, analyze the main demographic factors influencing vaccination behavior, and further assess the potential association between influenza vaccination during pregnancy and the occurrence of preterm birth, providing empirical evidence for influenza vaccination strategies in China. Methods All the information of the mothers and their newborns from January 1, 2012 to December 31, 2022 in the Shanghai Birth Medical Information System was collected. A multivariate logistic regression model was used to analyze the main demographic factors influencing influenza vaccination among pregnant women and to evaluate the association between influenza vaccination during pregnancy and preterm birth outcomes. Results During the study period, 2209 pregnant women received influenza vaccination. Multivariate logistic regression analysis revealed that maternal residency, age, education, spouse’s age and education, history of miscarriage, and offspring birth year were significant factors influencing influenza vaccination during pregnancy (all P<0.001). Compared with pregnant women registered in Shanghai, those with residency outside Shanghai had a lower likelihood of vaccination (adjusted OR=0.83, 95% CI: 0.76-0.91). Compared to women aged < 25 years, those aged 25-34 years (adjusted OR=2.65, 95% CI: 1.75-4.00) and ≥ 35 years (adjusted OR=3.35, 95% CI: 2.19-5.14) had higher likelihoods of vaccination. Women whose spouses were ≥ 35 years old were more likely to be vaccinated compared with those whose spouses were < 25 years old (adjusted OR=2.74, 95% CI: 1.57-4.78). Women with a college degree or above had a higher likelihood of vaccination than those with less than college education (adjusted OR=5.63, 95% CI: 4.30-7.38), and similarly, women whose spouses had a college degree or above were more likely to be vaccinated compared to those whose spouses had lower education (adjusted OR=2.19, 95% CI: 1.78-2.69). Women with a history of miscarriage were less likely to be vaccinated compared with those without (adjusted OR=0.76, 95% CI: 0.70-0.84). Compared to offspring born between 2012 and 2015, women with offspring born between 2016 and 2019 (adjusted OR=8.70, 95% CI: 6.45-11.75) and between 2020 and 2022 (adjusted OR=54.56, 95% CI: 40.79-72.97) were significantly more likely to receive influenza vaccination during pregnancy. After adjusting for maternal residency, age, education, spouse’s age and education, single/multiple pregnancies, history of miscarriage, gestational hypertension, gestational diabetes, and offspring birth year, influenza vaccination during pregnancy was associated with a 35% reduction in the risk of preterm birth compared to that of no vaccination during pregnancy (adjusted OR=0.65, 95% CI: 0.53-0.81). Conclusions Multiple sociodemographic factors are significantly associated with influenza vaccination behavior among pregnant women in Shanghai between 2012 and 2022, and influenza vaccination during pregnancy may be related to a reduced risk of preterm birth. It is recommended to further strengthen public education and service support, continuously promote vaccination efforts, and effectively safeguard maternal and infant health.

Key words: influenza vaccine, pregnancy, demographic characteristics, preterm birth