A cryptic pregnancy is one in which one does not know that they are pregnant until they are in labour.
If the pregnancy is very smooth-going and no problems encountered, then there would not be any reason to experience bleeding during this time until the onset of spontaneous labour in which case the "show" (dislodging of the mucus plug from the cervical opening) would occur.
If, however, there was an instance of threatened miscarriage, then there would be unexpected per vaginal bleeding and this may or may not be accompanied with pelvic pain. This would hopefully spur the woman to then see a gynaecologist for urgent help.
