That and the point that childbirth in a hospital with all the medical protection and support for mother and child is simply something a number of people cannot afford. And even with insurance, co-pay can make a baby a ruinous venture. So they give birth at home (“like the founding fathers”, err, mothers did), with maybe a midwife. Any serious complication, and child and/or mother are done for.

Another reason is the low vaccination level in the USA. At least low for a rich country.