A burning threat to pregnant women

F rom the examination table, Sagobai chats as her doctor moves the ultrasound wand across the dome of her belly. Aged 20, she is pregnant for the third time. She feels fine now, she says, but in recent months—during a prolonged heatwave in Pakistan’s Sindh with temperatures reaching 49°C (120°F)—she had often felt dizzy and dehydrated. The heat is more intense than it used to be, and she worries that it might be bad for both her and the baby. A research team, led by Dr Jai Das at the Aga Khan University in Karachi, is investigating that question, too. Each year more than 4.5m women and babies around the world die during pregnancy, childbirth or in the weeks following—about one death every seven seconds. Hundreds of thousands of these, and increasingly more, are affected by heat. Sagobai is one of 400 women taking part in the world’s largest study trying to understand why. Nearly 6,000 other pregnant women will join her. The task is formidable. Each woman is recruited before her 13th we

F rom the examination table, Sagobai chats as her doctor moves the ultrasound wand across the dome of her belly. Aged 20, she is pregnant for the third time. She feels fine now, she says, but in recent months—during a prolonged heatwave in Pakistan’s Sindh with temperatures reaching 49°C (120°F)—she had often felt dizzy and dehydrated. The heat is more intense than it used to be, and she worries that it might be bad for both her and the baby. A research team, led by Dr Jai Das at the Aga Khan University in Karachi, is investigating that question, too. Each year more than 4.5m women and babies