This retrospective cohort study evaluated safety and coverage of maternal influenza, pertussis, and COVID-19 vaccination among pregnant women delivering at the Women’s and Children’s Hospital in South Australia between 2020 and 2023. The analysis used linked maternity and immunisation data to examine associations between vaccination in pregnancy and a range of maternal, perinatal, and neonatal outcomes, and to identify determinants of vaccine uptake.
The cohort comprised 19,098 pregnant women who delivered at a single tertiary hospital from 2020–2023. Time-to-event perinatal outcomes were analysed using Cox proportional-hazards models to estimate hazard ratios. Time-independent outcomes were modelled with log-binomial regression, and Poisson regression models estimated adjusted prevalence ratios (aPRs) to determine factors associated with maternal vaccine uptake. The study population, analytic approaches, and outcomes were reported in the abstract as the basis for safety and coverage assessment.
Overall uptake during pregnancy reported in the cohort was:
These figures reflect vaccine receipt during pregnancy in the study period and form the foundation for subsequent safety and effectiveness analyses described in the report.
The study found no association between maternal vaccination (influenza, pertussis, or COVID-19) and increased risks of several obstetric complications. Specifically, vaccinated mothers did not have higher rates of hypertensive disorders, chorioamnionitis, premature rupture of membranes, antepartum haemorrhage, postpartum haemorrhage, small-for-gestational-age infants, or low birthweight. Both influenza and pertussis vaccination were associated with a lower likelihood of experiencing at least one obstetric complication (influenza aRR 0.94, 95% CI 0.91–0.98; pertussis aRR 0.89, 95% CI 0.86–0.92).
A small increase in diagnosed gestational diabetes was observed among women vaccinated against influenza or pertussis; the abstract reports this as a modest association without further detail on effect size or clinical implications.
The study reports protective associations between maternal vaccination and reduced preterm birth. Influenza vaccination was associated with a 13% protective effect against preterm birth. Pertussis vaccination was associated with a 17% reduction in preterm birth and, as reported in the abstract, nearly 50% fewer stillbirths among vaccinated women. COVID-19 vaccination during pregnancy was associated with a reduced hazard for preterm birth (adjusted hazard ratio 0.79, 95% CI 0.68–0.92).
These findings support added perinatal benefits beyond the absence of harm, as observed across multiple vaccine types in this cohort.
Neonatal outcomes were generally more favourable among infants born to vaccinated mothers. The abstract reports lower rates of neonatal resuscitation, lower rates of early-onset sepsis, and fewer low Apgar scores in infants whose mothers received influenza, pertussis, or COVID-19 vaccines during pregnancy. The report frames these neonatal findings as additional benefits associated with maternal immunisation.
The study identified sociodemographic and clinical factors associated with lower maternal vaccine uptake. Women who were younger, multiparous, unmarried, or First Nations were less likely to have been vaccinated during pregnancy. Lower uptake was also observed among mothers whose infants were discharged to non-parental care. The authors underscore that these persistent inequities indicate a need for targeted, culturally safe strategies to improve equitable vaccine access and protection for pregnant women and their infants.
The abstract does not detail all study limitations; readers are referred to the full text for complete methodological and limitation discussion. The study was supported by an NHMRC Partnership grant (APP2014684). The authors state the funding bodies had no role in study design or manuscript writing. Several authors’ institutions receive funding for investigator-led studies from vaccine manufacturers (Pfizer, Sanofi Pasteur, and GSK), and this is disclosed as a potential competing interest.
In this large Australian maternity cohort, maternal influenza, pertussis, and COVID-19 vaccination were not associated with increased obstetric risk and were linked to reductions in preterm birth, stillbirth, and several adverse neonatal outcomes. The authors conclude that these findings reaffirm safety and added benefits of maternal immunisation while highlighting inequities in vaccine uptake that require culturally appropriate, targeted interventions to ensure equitable protection across all groups. For full numerical details, stratified analyses, and discussion of limitations, consult the full published article.