Ambient temperature and stillbirth risks in northern Sweden, 1880–1950

• Published in: Environmental Epidemiology
• Main Authors: Karlsson, Lena, Junkka, Johan, Häggström Lundevaller, Erling, Schumann, Barbara
• Format: Article in Journal/Newspaper
• Language: English
• Published: Umeå universitet, Enheten för demografi och åldrandeforskning (CEDAR) 2021
• Subjects: Stillbirth; Ambient temperature; Seasonality; Environment; Climate vulnerability; Sweden; Public Health; Global Health; Social Medicine and Epidemiology; Folkhälsovetenskap; global hälsa; socialmedicin och epidemiologi; Obstetrics; Gynecology and Reproductive Medicine; Reproduktionsmedicin och gynekologi; Social and Economic Geography; Social och ekonomisk geografi; Northern Sweden; Subarctic
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-189202; https://doi.org/10.1097/EE9.0000000000000176

Background: Climate vulnerability of the unborn can contribute to adverse birth outcomes, in particular, but it is still not well under-stood. We investigated the association between ambient temperature and stillbirth risk among a historical population in northern Sweden (1880–1950). Methods: We used digitized parish records and daily temperature data from the study region covering coastal and inland communi-ties some 600 km north of Stockholm, Sweden. The data included 141,880 births, and 3,217 stillbirths, corresponding to a stillbirth rate of 22.7 (1880–1950). The association between lagged temperature (0–7 days before birth) and stillbirths was estimated using a time-stratified case-crossover design. Incidence risk ratios (IRR) with 95% confidence intervals were computed, and stratified by season and sex. Results: We observed that the stillbirth risk increased both at low and high temperatures during the extended summer season (April to September), at −10°C, and the IRR was 2.3 (CI 1.28, 4.00) compared to the minimum mortality temperature of +15°C. No clear effect of temperature during the extended winter season (October to March) was found. Climate vulnerability was greater among the male fetus compared to the female counterparts. Conclusion: In this subarctic setting before and during industrialization, both heat and cold during the warmer season increased the stillbirth risk. Urbanization and socio-economic development might have contributed to an uneven decline in climate vulnerability of the unborn.