High Temperatures and Spontaneous Abortion: A systematic Review and Meta-analysis.
1
College of Health and Public Servcie, university of North Texas, Denton, United States
Popul. Med. 2026;8(Supplement Supplement 1):
ABSTRACT
BACKGROUND:
Rising global temperatures due to climate change have raised concerns about their impact on reproductive health outcomes. Evidence on the association between high ambient temperatures and spontaneous abortion remains fragmented. This study aimed to systematically review and quantitatively synthesize the existing literature on the impact of high temperatures on the risk of spontaneous abortion.
METHODS:
We conducted a systematic review and meta-analysis following PRISMA guidelines. A comprehensive search of PubMed, Embase, Web of Science, and Scopus was conducted from inception to June 2025. Observational studies examining the association between high ambient temperature or heat exposure and spontaneous abortion were included. Pooled effect estimates were calculated using random-effects models. Heterogeneity was assessed using the I² statistic, and subgroup analyses were performed by exposure window, geographic region, and temperature metric.
RESULTS:
A total of 18 studies met the inclusion criteria, representing over 3.2 million pregnancies across North America, Europe, Asia, and Australia. Exposure to high ambient temperatures was significantly associated with an increased risk of spontaneous abortion, with a pooled relative risk (RR) of 1.12 (95% CI: 1.05–1.19) comparing extreme heat exposure to reference temperatures. The association was strongest for heat exposure during the first trimester (RR: 1.18, 95% CI: 1.08–1.29). Subgroup analyses showed stronger effects in regions with higher baseline temperatures and in studies using heatwave definitions rather than continuous temperature measures. Moderate heterogeneity was observed across studies (I² = 61%). Sensitivity analyses excluding lower-quality studies yielded similar results.
CONCLUSIONS:
High ambient temperature exposure is associated with an increased risk of spontaneous abortion, particularly during early pregnancy. These findings suggest that pregnant individuals represent a vulnerable population in the context of climate change and highlight the importance of heat-mitigation strategies to reduce adverse pregnancy outcomes.
Rising global temperatures due to climate change have raised concerns about their impact on reproductive health outcomes. Evidence on the association between high ambient temperatures and spontaneous abortion remains fragmented. This study aimed to systematically review and quantitatively synthesize the existing literature on the impact of high temperatures on the risk of spontaneous abortion.
METHODS:
We conducted a systematic review and meta-analysis following PRISMA guidelines. A comprehensive search of PubMed, Embase, Web of Science, and Scopus was conducted from inception to June 2025. Observational studies examining the association between high ambient temperature or heat exposure and spontaneous abortion were included. Pooled effect estimates were calculated using random-effects models. Heterogeneity was assessed using the I² statistic, and subgroup analyses were performed by exposure window, geographic region, and temperature metric.
RESULTS:
A total of 18 studies met the inclusion criteria, representing over 3.2 million pregnancies across North America, Europe, Asia, and Australia. Exposure to high ambient temperatures was significantly associated with an increased risk of spontaneous abortion, with a pooled relative risk (RR) of 1.12 (95% CI: 1.05–1.19) comparing extreme heat exposure to reference temperatures. The association was strongest for heat exposure during the first trimester (RR: 1.18, 95% CI: 1.08–1.29). Subgroup analyses showed stronger effects in regions with higher baseline temperatures and in studies using heatwave definitions rather than continuous temperature measures. Moderate heterogeneity was observed across studies (I² = 61%). Sensitivity analyses excluding lower-quality studies yielded similar results.
CONCLUSIONS:
High ambient temperature exposure is associated with an increased risk of spontaneous abortion, particularly during early pregnancy. These findings suggest that pregnant individuals represent a vulnerable population in the context of climate change and highlight the importance of heat-mitigation strategies to reduce adverse pregnancy outcomes.
| eISSN: | 2654-1459 |
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