Implantation is a complex process in which the already fertilized egg embeds in the uterine mucosa which is already prepared to receive the egg. It is presented with cramps in the lower part of the abdomen. Small amounts of blood might be present in certain women and are called implantation bleeding. The blood originates from the miniature wound in the mucosa that is formed to receive the egg.


The implantation occurs approximately seven days after fertilization. Given the fact that the fertilization is usually on the ovulation day, which is always fourteen days before the start of the next menstrual period, the implantation usually occurs seven days before the expected start of the next menstrual period. In your case (27 days normal menstrual cycle length) implantation is expected to occur approximately at the 20th day of your menstrual cycle.


You might want to wait and visit your gynecologist to check whether you are pregnant which might explain the implantation cramps.