How late can a baby be born?

Babies born after the 42nd week of pregnancy are considered extremely late term. Some babies are born even later than this, but those are very rare cases. The average pregnancy lasts about 40 weeks, so a baby born after the 42nd week is considered to be two weeks overdue. Studies show that the placenta starts to age beyond 37 weeks and can eventually start losing its ability to keep up with your baby’s needs. In addition, as the baby grows larger and fluid around the baby decreases, there is a greater risk of issues developing.