Babies were cradled on hips

From To Kill a Mockingbird. It's the day of Tom Robinson's trial.

The courthouse square was covered with picnic parties sitting on newspapers, washing down biscuit and syrup with warm milk from fruit jars. ... Some invisible signal had made the lunchers on the square rise and scatter bits of newspaper, cellophane, and wrapping paper. Children came to mothers, babies were cradled on hips as men in sweat-stained hats collected their families and herded them through the courthouse doors.

What does "cradled on hips" mean? I assume the parents of the babies were standing or walking, so I'm not sure how the babies could be on their hips.