Villages in the Lower Shire valley of Malawi, like this one named Jasi, rely heavily on subsistence farming and steady rainfall, and are struggling to produce steady harvests. Jennifer Ludden/NPR hide caption

itoggle caption Jennifer Ludden/NPR

Christina Asima says she had no choice but to marry last year at age 12 to help care for younger siblings after her mother abandoned the family. But she says her husband was abusive, so she left him, and now must look after her 8-month-old son, Praise, alone. Jennifer Ludden/NPR hide caption

itoggle caption Jennifer Ludden/NPR

By taking antiretroviral drugs during pregnancy, this Tanzanian mother lowered the risk of passing HIV to her daughter. Siegfried Modola/AFP/Getty Images hide caption

itoggle caption Siegfried Modola/AFP/Getty Images

Twins in Malawi helped scientists discover a role the gut microbiome appears to play in severe malnutrition. Photograph courtesy of Tanya Yatsunenko hide caption

itoggle caption Photograph courtesy of Tanya Yatsunenko