your baby tamagotchi's parent will leave the baby in two midnights.
also, i just felt the urge to help,umm, oh yeah, you can make you baby's parent leave early. this only works when the parent and baby have spent one midnight together. after one midnight, you can set the time to one minute before midnight and wait one minute. the parent should leave. if it doesnt, just do it again at a later time in the day.