Climate change and vertically transmissible infections in maternal and neonatal populations: a systematic review

Climate change influences infectious disease dynamics and disrupts maternal and neonatal health services, both of which are pathways through which the risk of vertically transmissible infections may increase.

We systematically reviewed evidence on the association between climate-related environmental exposures and infection-related outcomes relevant to vertical transmission in pregnant or intrapartum women, neonates, and infants. Screening, extraction, and risk-of-bias assessment were performed independently in duplicate. Owing to substantial heterogeneity, findings were synthesised narratively. GRADE scoring was used to assess certainty of evidence.

Of 4,579 records identified, 42 full texts were reviewed and 6 studies included. Studies examined drought/famine, temperature, humidity, and climate zone in relation to HIV, group B streptococcus (GBS), varicella-zoster virus (VZV), and bacterial meningitis. No study reported vertical transmission as an outcome. Higher temperature and humidity were associated with increased maternal GBS colonisation. Three studies suggested cooler and/or drier conditions were associated with increased VZV transmission or earlier serological acquisition. One study found drought-associated famine was linked to increased HIV prevalence in pregnant women in rural Malawi. Certainty of evidence was very low across outcome groupings.

This review found evidence suggesting climate-related exposures may be associated with infections relevant to vertical transmission through pathogen-specific biological pathways, broader social disruption, and deprivation. There is currently insufficient evidence to determine the impact of climate change on vertical transmission or related outcomes. Closing this gap should be a priority for research and climate adaptation in maternal and neonatal health.

https://www.crd.york.ac.uk/PROSPERO/view/CRD420251124435, PROSPERO CRD420251124435.