COVID-19 Vaccination in Pregnancy: The Impact of Multimorbidity and Smoking Status on Vaccine Hesitancy, a Cohort Study of 25,111 Women in Wales, UK

This research has not been peer-reviewed. It is a preliminary report that should not be regarded as conclusive, guide clinical practice or health-related behaviour, or be reported in news media as established information.


Multimorbidity and pregnancy are two risk factors for more severe outcomes after a SARS-CoV-2 infection, thus vaccination uptake is important for pregnant women living with multimorbidity. This study aimed to examine the impact of multimorbidity, smoking status, and demographics (age, ethnic group, area of deprivation) on vaccine hesitancy among pregnant women in Wales using electronic health records (EHR) linkage.


This cohort study utilised routinely collected, individual-level, anonymised population-scale linked data within the Secure Anonymised Information Linkage (SAIL) Databank. Pregnant women were identified from 13th April 2021 to 31st December 2021. Survival analysis was utilised to examine and compare the length of time to vaccination uptake in pregnancy by multimorbidity and smoking status, as well as depression, diabetes, asthma, and cardiovascular conditions independently. Variation in uptake by; multimorbidity, smoking status, and demographics was examined jointly and separately for the independent conditions using hazard ratios (HR) from the Cox regression model. A bootstrapping internal validation was conducted to assess the performance of the models.


Within the population cohort, 8,203 (32.7%) received at least one dose of the COVID-19 vaccine during pregnancy, with 8,572 (34.1%) remaining unvaccinated throughout the follow-up period, and 8,336 (33.2%) receiving the vaccine postpartum. Women aged 30 years or older were more likely to have the vaccine in pregnancy. Those who had depression were slightly but significantly more likely to have the vaccine compared to those without depression (HR = 1.08, 95% CI 1.03 to 1.14, p = 0.02). Women living with multimorbidity (> 1 health condition) were 1.12 times more likely to have the vaccine compared to those living without multimorbidity (HR = 1.12, 95% CI 1.04 to 1.19, p = 0.001). Vaccine uptakes were significantly lower among both current smokers and former smokers compared to never smokers (HR = 0.87, 95% CI 0.81 to 0.94, p < 0.001 and HR = 0.92, 95% CI 0.85 to 0.98, p = 0.015 respectively). Uptake was also lower among those living in the most deprived areas compared to those living in the most affluent areas (HR = 0.89, 95% CI 0.83 to 0.96, p = 0.002). The validated model had similar performance and revealed that multimorbidity, smoking status, age, and deprivation level together have a significant impact on vaccine hesitancy (p < 0.05 for all).


Younger women, living without multimorbidity (zero or only one health condition), current and former smokers, and those living in the more deprived areas are less likely to have the vaccine, thus, a targeted approach to vaccinations may be required for these groups. Women living with multimorbidity are slightly but significantly less likely to be hesitant about COVID-19 vaccination when pregnant.

Author list



  1. National Centre for Population Health and Wellbeing Research, Swansea University Medical School, Faculty of Medicine, Health and Life Science, Swansea, Wales, UK
  2. Population Data Science, Swansea University Medical School, Faculty of Medicine, Health and Life Science, Swansea, Wales, UK
  3. Health Data Science Centre, Fondazione Human Technopole, Milan, Italy
  4. School of Medicine, University of St Andrews, Scotland, UK and Hospital Rey Juan Carlos. Instituto de Investigación Sanitaria Fundación Jimenez Diaz. Madrid. Spain
  5. Research and Evaluation Division, Public Health Wales, UK
  6. Institute of Applied Health Research, Birmingham University, Birmingham, UK


M Mhereeg1*, H Jones1, J Kennedy1, M Seaborne1, M Parker1, N Kennedy1, A Akbari2, L Zuccolo3, A Azcoaga-Lorenzo4, A Davies5, K Nirantharakumarand S Brophy1

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