A systematic review of 6 studies found suggestive associations between climate factors (temperature, humidity, drought) and infections relevant to pregnancy and vertical transmission, but certainty of evidence was very low and no study directly measured transmission outcomes.
Researchers conducted a systematic review to understand how climate-related environmental changes might affect infections transmitted from mother to infant during pregnancy or birth. They screened nearly 4,600 studies and ultimately included 6 that examined the relationship between climate exposures and infections like HIV, group B streptococcus (GBS), varicella-zoster virus (VZV), and bacterial meningitis in pregnant women or newborns.
The findings were suggestive but limited. Higher temperature and humidity were associated with increased maternal GBS colonisation, the bacterial carriage state that poses risk during delivery. Three studies indicated that cooler and drier conditions correlated with higher VZV transmission rates or earlier acquisition of immunity to chickenpox in population samples. One study from rural Malawi linked drought-associated famine to elevated HIV prevalence in pregnant women. However, the researchers emphasised that certainty of evidence was very low across all findings. Critically, no included study directly measured vertical transmission rates, instead relying on proxy measures like maternal colonisation status or serological markers.
The review identified two broad mechanistic pathways through which climate change could increase these risks. First, pathogens respond directly to environmental conditions: bacterial colonisation rates shift with temperature and humidity; viral transmission patterns vary by season and climate zone. Second, climate disruption degrades maternal and neonatal health systems and increases poverty and malnutrition, both of which amplify infection susceptibility and reduce access to preventive interventions like vaccination or antiretroviral therapy.
The authors concluded that the evidence base is far too thin to establish whether climate change meaningfully increases vertical transmission risk. They flagged this as a critical research gap, particularly given that maternal and neonatal health is already vulnerable in regions most exposed to climate hazards.
This review does not establish that climate change currently increases personal risk of vertically transmitted infections. Instead, it identifies a research gap: we lack direct evidence on whether climate exposures actually increase rates of infection-related complications in pregnancy and childbirth.
For pregnant individuals or those planning pregnancy, the practical signal is modest. Standard infection prevention measures remain evidence-based: prenatal HIV testing and treatment, GBS screening in the third trimester, varicella immunity assessment, and completion of recommended vaccinations. These interventions work regardless of climate baseline. If you live in a region experiencing drought, food insecurity, or heat stress, prioritising access to antenatal care and infection screening becomes even more important, since the review suggests these stressors may compound infection risk.
Clinically, this review suggests that maternal-fetal medicine and public health systems in climate-vulnerable regions should monitor sentinel infections and consider how climate adaptation strategies can maintain infection control capacity. But adaptation decisions should not wait for perfect evidence; they should integrate climate resilience into existing maternal health infrastructure now.
| Attribute | Details |
|---|---|
| Study Type | Systematic review with narrative synthesis |
| Included Studies | 6 full texts reviewed and included from 4,579 initial records |
| Infections Examined | HIV, group B streptococcus (GBS), varicella-zoster virus (VZV), bacterial meningitis |
| Climate Exposures | Temperature, humidity, drought/famine, climate zone |
| Outcomes Measured | Maternal colonisation, seroprevalence, infection prevalence; no direct vertical transmission outcomes |
| Certainty of Evidence | Very low across all findings (GRADE assessed) |
| Journal | Frontiers in Global Women's Health |
| PubMed ID | 42846302 |
| PROSPERO Registration | CRD420251124435 |
Frontiers in Global Women's Health. "Climate change and vertically transmissible infections in maternal and neonatal populations: a systematic review." PubMed. https://pubmed.ncbi.nlm.nih.gov/42846302
ProtocolEngine provides general health information based on published research. This is not medical advice. Consult a healthcare professional before starting any supplement or health protocol.