The World Health Organization has endorsed waiting to clamp the umbilical cord for at least one minute after a baby is born. Sebastien Desarmaux/Godong/Science Source hide caption

toggle caption Sebastien Desarmaux/Godong/Science Source

Children under age 2 can reason abstractly, researchers say. Jandrie Lombard/iStock hide caption

toggle caption Jandrie Lombard/iStock