Good Timing C-sections best for baby when close to due date. (AP) -- Babies do better after a scheduled Caesarean section if they're born no sooner than seven days before their due date, a new large study of U.S. births shows. Those delivered earlier had more complications, including breathing problems, even though they were full term, the researchers reported in Thursday's New England Journal of Medicine. Even just a few days made a difference, they said.