A daycare class is held in a Washington, DC park on a warm morning on April 12.ANDREW CABALLERO-REYNOLDS/Getty Images Peggy O’Donnell Heffington is the author of Without Children: The Long History of Not Being a Mother. On a Wednesday morning in March, several hundred parents and early childhood educators met in downtown New Haven, the state capital of Connecticut, for a rally they called the Morning Without Childcare. Instead of protest chants, the group sang nursery songs such as If You’re Happy And You Know It and You Are My Sunshine, but their signs were serious and to the point....