The Khoe-San people of southern Africa carry a genetic mutation that reduces pregnancy complications, according to a study in the journal PLOS Genetics. The gene variant can alter the formation of the placenta during the early stages of pregnancy, resulting in larger, healthier babies and reducing the likelihood of pre-eclampsia, a disorder that can be fatal. The click-speaking Khoe-San are thought to have broken off from other African groups 100,000 years ago and, like other sub-Saharan populations, have high genetic diversity.