Whether she was shooting down the road in London or in the remote villages of Malawi, photographer Jenny Lewis gave herself an unbreakable set of rules. One Day Young was to document mothers within one day of childbirth and no later; the mothers were not to be dressed or posed or made up to conform to any preconceived ideas about maternity. She was to sit with them in their own homes, listen to them, and make pictures of the very moment in which their lives were irrevocably changed.