Sweat safely during pregnancy

Research-approved temps for outdoor workouts, saunas, and swims

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Pregnant women can safely engage in activities that raise their body temperature—like exercising in warm weather, taking hot baths, and sitting in a sauna—without risking harm to their baby, according to a new analysis in the British Journal of Sports Medicine.

Historically, the concern with pregnant women working out in high temps was that they’d overheat. Earlier animal studies show that if the core body temperature hits 105 degrees during gestation, it can lead to abnormalities in the baby and other complications, explains study author Ollie Jay, Ph.D., director of the Thermal Ergonomics Laboratory at the University of Sydney.

According to the new analysis, exercising in 77-degree weather only raised pregnant women’s core temps to 101 degrees, below the 102-degree danger zone for humans. Bathing, swimming, and sitting in saunas had lesser effects. Despite a lack of research, Jay says that sweating in even hotter climates is probably safe for these women, too.

The analysis shows that without risking their health, pregnant women—in any trimester—can train in 77-degree conditions at 90 percent of their maximum heart rate for up to 35 minutes, swim in a warm pool for up to 45 minutes, and recover in a hot bath or sauna for up to 20 minutes.

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