The impact of ambient temperature on preeclampsia admissions in cold regions of developing countries: a distributed lag analysis in Harbin, China.

BACKGROUND

The relationship between ambient temperatures, elevated blood pressure, and hypertensive disorders of pregnancy (HDP) has been documented. Nonetheless, limited research has examined the immediate impact of ambient temperature on preeclampsia admissions in cold regions of developing nations.

METHODS

The study utilized data from preeclampsia patients in the case information system of the First Affiliated Hospital of Harbin Medical University from 2017 to 2021, as well as ambient temperature and air pollutant concentrations from the China Integrated Meteorological Information Service System (CIMISS). The distributed lag nonlinear model (DLNM) was employed to examine the short-term impacts of ambient temperature on preeclampsia admissions in this cold region, considering daily mean temperature, daily minimum temperature, and daily maximum temperature.

RESULTS

When preeclampsia was stratified into two subgroups according to temperature, a notable increase in hospital admissions for preeclampsia was noted at lower temperatures. Short-term effects were assessed using relative risk (RR) and its corresponding 95% confidence interval (CI) for both a single daily lag (ranging from lag 0 to lag 30 days) and a cumulative lag (ranging from lag 0 to lag 0–30 days). The daily mean temperature exhibited varying effects on the risk of preeclampsia, with the very cold temperature threshold (-20.08 °C) showing the largest lag effect (RR = 2.81) within a cumulative lag of 0–10 days, resulting in more than a doubling of the cumulative relative risk. Conversely, the very hot temperature threshold (25.18 °C) was associated with a reduction of more than 10% in the cumulative risk of preeclampsia (RR = 0.89) within the same lag period. Similar trends were observed for two additional temperature thresholds. Furthermore, younger preeclampsia patients under the age of 35 who had not reached full term were found to be more susceptible to the effects of cold ambient temperatures.

CONCLUSIONS

Our study in Harbin revealed that brief exposure to cold temperatures is associated with a heightened likelihood of hospitalization for preeclampsia, particularly among individuals under the age of 35 and those with preterm preeclampsia. It is imperative for healthcare professionals to closely monitor these subgroups during periods of decreased ambient temperatures.