Original
The ganglion cells in the large, and sometimes in the small intestine do not form during pregnancy.
There for the fecal matter doesn't pass or sometimes it does pass but not very much which will sometime require surgery to remove the affected bowel, some surgeries are straight forward and can be cut and restitch and some require a ostomy bag of some sort. Some require the ostomy bag for a temporary amount of time, some require it for the rest of their life.
Some do not need surgery and can be managed with a specific diet.