Heat wave: women are more at risk of dying than men. We tell you why

Many studies have focused on mortality during heat waves. Dutch researchers have analyzed around 60 studies on this subject and have concluded that women, especially those over the age of 65, die more during heat waves than men. For example, the heat wave that hit France in the summer of 2003 caused more deaths among women than among men, with a 15% higher mortality rate.

Heat more “deadly” in women

Other work, carried out by researchers from the University of Amsterdam, had concluded that heat-related mortality in the Netherlands was higher in women than in men. A finding observed especially in people aged 80 and over exposed to extreme heat. On the other hand, no difference between the sexes was found in case of exposure to cold.

This increased health risk was confirmed by another study published in the journal Nature Medicine which looked at the 60,000 people who died during the heat wave that hit Europe in the summer of 2022. The study concluded that the deaths of women were 56% higher than those of men, specifying that there were variations by age group.

Genetic, hormonal and physical inequalities

Although they remain to be confirmed, several hypotheses have been put forward to explain this difference between the sexes. Certain physiological characteristics specific to women would be responsible for a poorer regulation of body temperature than that observed in men.

• First, women sweat half as much as men. However, we know that perspiration is a natural mechanism that allows the temperature to drop when the body is overheated;
• Second, women experience a slight increase in body temperature at certain times of the cycle (just before ovulation) and during menopause. A hormonal phenomenon could therefore also be involved in this vulnerability to heat;
• Another hypothesis evoked to explain the increased sensitivity of women to high temperatures, their physique. “Women get hot faster because they have less body surface area than men. They are more quickly overwhelmed by heat. Also, they have a different distribution of fat than men, which can play a role in perspiration.”, explains Dr. Gérald Kierzek, emergency doctor and medical director of Doctissimo.

A more fragile cardiovascular system?

Cardiovascular failure being one of the main causes of heat-related mortality, this avenue has also been explored to understand the differences between men and women. According to Nabila Bouatia-Naji, director of research at Inserm interviewed by our colleagues from Releasethe heat would have “a greater negative effect on the cardiovascular system of women”. She explains : “blood pressure rises and the heart has to compensate. He pumps, but being more fragile due to age, he finds it difficult to hold”. Finally, women have a higher cardiovascular strain than men, which could be a determining factor. “There is an overrepresentation of women among hypertensives and they are more at risk of stroke”points out Nabila Bouatia-Naji.

More generally, it is important to remember that we are physically unequal in the face of heat. It’s not just a question of gender. Each person has their own “thermostat”, and will need to maintain a temperature that is sometimes different from that of their neighbour. On the other hand, the right actions to avoid heat-related health problems (to be found in the video below) apply to everyone!