Background: Previous studies explored the influence of temperature on stillbirth, but the impact of extreme temperature events including the duration, intensity and frequency affect the risk of stillbirth remains controversial. Studies on the associations between extreme temperature events (ETEs) and stillbirths considering biologic vulnerability phenotypes are lacking. Methods: Data on the China Birth Cohort Study (CBCS), nationwide large pregnancy cohort study conducted in 2018-2022 were combined with daily meteorological variables extracted from the validated grid datasets corresponding to each subject's geocoded residential address. A set of cutoff temperature thresholds (2.5th, 5th, 7.5th, 10th, 90th, 92.5th, 95th and 97.5th percentiles of daily apparent temperature of each province during the study period) and durations (2, 3, and 4 consecutive days) were utilized to define 24 distinct ETEs. An extended Cox regression model with time-varying variables was used to estimate the effects of ETE exposures during the final week on stillbirth. Results: A total of 244, 204 singleton births from 47 hospitals of 17 provinces in China were included, among which 942 (3.9‰) stillbirths (≥20 weeks’gestation excluding terminations of pregnancy). Under different ETE definitions, the hazard ratios (HRs) of stillbirth associated with heat wave and cold spell ranged from 1.36 (95% CI: 1.03, 1.80) to 1.83 (95% CI: 1.16, 2.87), and 0.78 (95% CI: 0.62, 0.98) to 1.20 (95% CI: 0.84, 1.72), respectively. The effects varied across regions, and lower population density, physicians per 1000 people and greater number of hospital beds per 1000 persons were protective factors for the effects. The risk of stillbirth in those experiencing two heatwaves was significantly higher than that in cases experiencing only one heat wave. Exposed to heat wave, the risk of stillbirths with biologic vulnerability phenotypes including preterm birth (PTB), low birth weight (LBW) and small for gestational age (SGA) was higher. Conclusions: Our research confirms the evidence that exposure to ETEs during the final gestational week can trigger stillbirth, with risk increasing based on the duration, intensity and frequency, and varying across regions. Heat waves also increased the risk of stillbirths, particularly with PTB, LBW and SGA. In the context of climate change, these findings highlight the urgent need to protect vulnerable populations, especially fetuses.
| Published in | Abstract Book of ICPHMS2025 & ICPBS2025 |
| Page(s) | 42-43 |
| Creative Commons |
This is an Open Access abstract, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited. |
| Copyright |
Copyright © The Author(s), 2025. Published by Science Publishing Group |
Extreme Temperature Events, Heatwave, Cold Spell, Stillbirth
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