Environmental extreme temperature and daily preterm birth in Sabzevar, Iran: a time-series analysis

• Published in: Environmental health and preventive medicine Vol. 24; no. 1; p. 5
• Main Authors: Mohammadi, Danial, Naghshineh, Elham, Sarsangi, Alireza, Zare Sakhvidi, Mohammad Javad
• Format: Journal Article
• Language: English
• Published: England BioMed Central 05-01-2019; Komiyama Printing Co. Ltd
• Subjects: Air Pollutants - analysis; Air pollution; Arid regions; Birth; Body mass index; Brittleness; Child mortality; Climate; Climate change; Climate effects; Cold; Cold Temperature - adverse effects; Environmental exposure; Environmental Exposure - adverse effects; Environmental health; Environmental Monitoring - methods; Extreme cold; Female; Gestational age; Health risk assessment; Heat; Heat stress; Heat tolerance; Holidays & special occasions; Hospital Records; Hot Temperature - adverse effects; Humans; Humidity; Infant, Newborn; Iran - epidemiology; Poisson Distribution; Pollution; Pregnancy; Premature birth; Premature Birth - etiology; Risk; Risk Factors; Semi arid areas; Temperature; Temperature effects; Time series; Ultrasonic imaging; Womens health; Iran; Environmental exposure; Temperature; Heat stress; Premature birth
• ISSN: 1342-078X; 1347-4715
• DOI: 10.1186/s12199-018-0760-x

Most of the studies on the effect of heat stress on preterm birth (PTB) are conducted in temperate climates. Evidence on this effect in hot and arid countries with low and middle income is limited. This paper describes the short-term effect of exposure to the hot and cold environment on a daily number of PTB in Iran.
The daily number of PTB was obtained from all hospitals of the city. Meteorological and air pollution data from 2011 to 2017 were obtained from a metrological station in the city. A semi-parametric generalized additive model following a quasi-Poisson distribution with the distributed lag non-linear model was selected as a modeling framework for time-series analysis to simultaneously model the short-term and lagged effect of heat stress on PTB in the Sabzevar city.
The minimum and maximum daily temperature were - 11.2 and 45.4 °C respectively. The highest risk estimate at extreme cold temperature was found for apparent temperature (relative risk (RR) 1.83; 95% CI 1.61: 2.09). This pattern was seen for both models. For extreme hot temperatures, the model with mean temperature showed the highest risk increase for both the main model and air pollution adjusted model (RR 1.36; 95% CI 1.25: 1.49). The lowest risk estimate in extremely cold conditions was found in the model with mean temperature. However, for extremely hot temperature conditions, the lowest risk estimate was found for both maximum and apparent temperature.
Obstetricians working in semi-arid areas should be aware of the influence of environmental extreme temperature on the incidence of PTB.