Question: How and why does an egg implant itself outside of the uterus and then somtimes survive to full term? Also, what is this called?

Helen O'Connor answered on 21 Jun 2011:

Hi, this is called an ectopic pregnancy and can actually occur in about 1 in 100 pregnancies http://kidshealth.org/parent/pregnancy_center/your_pregnancy/ectopic.html

This happens when a fertilised egg implants itself outside the womb – most often this happens in a fallopian tube (a tubal pregnancy) or less often in an ovary, in the abdominal space or in the cervix.

There are some REALLY rare stories about babies that survive an ectopic pregnancy, but the chance of this is so rare, and the risks of an ectopic pregnancy are so great to the woman, that usually these pregnancies are terminated.