The study, led by Dr. Payam Dadvand, we measured the short-term impact of maternal exposure to environmental extremes during pregnancy in a sample of 7585 births that occurred during the period 2001-2005 in Barcelona.

They used national data on the heat and daily temperature for the period 1983-2006, using three indicators of conditions of extreme heat exposure based on the unusual heat and high humidity.

Thus, quantified the change in duration of pregnancy after maternal exposure to extreme heat. Thus, the results show that maternal exposure to extreme heat can have an immediate effect on the duration of pregnancy, and that these extreme temperatures are associated with a reduction in mean gestational age of the children.

Previous studies have pointed to increased vulnerability of pregnant women to heat, relating these extreme conditions with the induction of uterine contractions, increased secretion of hormones related to childbirth (oxytocin and prostaglandins) and an increase in levels of heat shock protein 70 associated with preterm birth.

Heat stress is a function of the interaction of internal heat production, the capacity of the heat loss to the environment and environmental heat load. During pregnancy, increased fat deposition and internal heat production due to fetal growth and metabolism.

Dadvand has acknowledged, although further studies are needed to confirm these results in different contexts, an episode of unusual warmth the day before delivery is associated with a reduction of average day of pregnancy.

He adds told the News and Information Service Science (SINC), these data could achieve a reduction of five days to more extreme values.

In fact, weather forecasts and taking into account that a reduction of up to one week in duration of pregnancy has been associated with adverse health outcomes of newborns, the authors argue that future studies should consider these factors to inform public health interventions appropriate to the subject.