Pharmacoepidemiology
Associations between COVID-19 vaccination during pregnancy and postpartum and human milk feeding initiation and continuation Elisabeth Brandstetter Figueroa* Elisabeth Brandstetter Figueroa Gabriela Vasquez-Benitez Kirsten Ehresman Elisabeth M Seburg Malini B DeSilva Yihe G Daida Kimberly K Vesco Abbey Sidebottom Heather S Lipkind Elyse O Kharbanda Kristin Palmsten
We assessed the association of COVID-19 vaccination during pregnancy and postpartum with human milk feeding initiation and duration.
Using EHR data from 3 geographically diverse healthcare systems, we included persons with a live birth (Jan ‘21-Oct ‘22), infant linkage, and milk feeding documentation (breast milk, formula or other milk, both). COVID-19 vaccination was determined from EHRs and state vaccine registries. Two analyses were performed based on timing of COVID-19 vaccination: pregnancy (≥20 weeks gestation vs no vaccination during pregnancy; N=10,757) and postpartum (≤6 months after delivery vs none; N=17,160). We estimated the adjusted prevalence ratio (aPR) for prenatal COVID-19 vaccination with human milk feeding initiation and continuation (at 2 and 6 months) using Poisson regression. We estimated the aHR for postpartum COVID-19 vaccination and human milk feeding discontinuation using a time-dependent Cox model. We used multiple imputation by chained equations for missing covariates, stabilized inverse probability of attrition weights to account for differences in those missing outcomes, and stabilized inverse probability of treatment weights to account for confounding by demographic, clinical, and socioeconomic characteristics, healthcare utilization, and calendar time.
In the pregnancy analysis, 36% received a COVID-19 vaccine. Among the unexposed, 95% initiated human milk feeding. Initiation did not differ by COVID-19 vaccination during pregnancy [aPR: 1.01 (1.00-1.02)]. Human milk feeding at 2 months [aPR: 1.02 (0.97-1.07)] and 6 months [aPR: 1.06 (0.98-1.15)] postpartum did not differ by prenatal COVID-19 vaccination. In the postpartum analysis, 26% received a COVID-19 vaccine. The human milk feeding discontinuation rate was 6/1,000 person-days in the unexposed. Discontinuation did not differ by postpartum vaccination [aHR: 1.03 (0.95-1.11)].
COVID-19 vaccination in pregnancy and postpartum were not associated with infant milk feeding practices.