Implantation is the term that is used when fertilized egg embed himself in the uterus. This occurs 7-10 days before due dates of periods or 5-7 days after ovulation. Some ladies have minor cramps at this time called implantation pain. This condition is not common like implantation bleeding which is also not common. If pain at the time of implantation is sever then it can be indication of ectopic pregnancy.