An Umbrella Review of the Impacts of Climate Change on Maternal Health and Birth Outcomes

OBJECTIVES: Climate change with its increasingly extreme weather and temperature events is posing significant challenges to human health, disproportionately impacting vulnerable populations like pregnant women and newborns. We synthesized evidence across published systematic reviews (SRs) on this topic.

METHODS: Following PRIOR guidelines, an umbrella review of previous SRs published in indexed databases between 2014 and 2024 was conducted. SRs presenting the impact of extreme temperatures or weather events on pregnancy, maternal, and newborn health outcomes were included. No geographical restrictions were applied. Guided by a protocol, dual screening and extraction was performed. SR quality was assessed using AMSTAR 2.

RESULTS: Of 1,983 search hits, eight SRs were included (global [n=5], China [n=1], Ireland [n=1], low- and middle-income countries [LMIC] [n=1]). Only the LMIC SR focused on extreme weather events, all other SRs investigated changes in temperature. All SRs presented birth outcomes; the LMIC SR focused on maternal outcomes (mortality, stress, and malnutrition). Independently of climate zones and study differences, the SRs consistently showed that exposure to extreme temperatures was correlated with increased risk of preterm birth, with some evidence also showing increased rates of low birth weight and stillbirths. These negative consequences were exacerbated among women in lower socioeconomic groups. Limited evidence was identified for setting critical exposure window periods or temperature thresholds associated with the worst outcomes. Also, a differentiation between climate zones was not consistently performed. SR quality varied and was often restricted by the availability of information across primary studies.

CONCLUSIONS: Globally, extreme weather events and temperatures increase health risks among mothers and their offsprings. Identifying pregnant women and their offsprings as a heat-health vulnerable group will prioritise research investment and policy decision-making to protect them from the consequences of climate change.