Shortly after her waters broke, Sarah Wynn-Williams was lying in hospital with her feet in stirrups, typing a work memo on her laptop between contractions. Facebook’s director of global public policy needed to send talking points from her recent trip to oversee the tech giant’s bid to launch operations in Myanmar to her boss Sheryl Sandberg. Then she would give birth to her first child. Wynn-Williams’s husband, a journalist called Tom, was livid but, as men tend to be in labour rooms, impotent. The doctor gently closed her laptop. “Please let me push send,” whimpered Sarah. “You should be pushing,”...