Exposure to extreme temperatures may increase the risk of preterm birth in a dose-response manner

Music City Center 

The frequency and severity of extreme temperatures have been increasing and are expected to continue to escalate in the coming decades. Relationships between extreme temperatures and early deliveries are not well understood. This study explores these relationships among 203,691 pregnant women in the Consortium on Safe Labor (CSL) study (2002-2008) with a novel spatially diverse extreme temperature exposure metric. Both extreme cold and heat were meaningfully associated with increased risks of early delivery, with relationships especially pronounced for third-trimester exposures. The strongest observed association was between extreme cold and early preterm birth (gestational age < 34 weeks), with the odds of these births over five times as likely relative to unexposed pregnancies. The likelihood of early delivery increased monotonically with higher proportions of days of exposure to extreme temperatures. We develop a novel constrained statistical inference-based methodology to test the hypothesis, which is statistically significant (p-value < 0.0001). Future work should seek to clarify underlying mechanisms and extend to recent data from the U.S. and other countries.

Extreme temperature exposures

Early deliveries

Pregnancy outcomes

Constrained statistical inference

Hypothesis testing

Matrix ordering 

Section on Statistics in Epidemiology