When does Implantation Happen?

Implantation occurs when an egg or other tissue attaches to the lining of the uterus. Implantation can cause a light bloody discharge due to the blood rich nature of the endometrial tissue. This can be the first sign of pregnancy, occurring before the actual missed menstrual cycle. It can also occur in diseases like endometriosis, which causes the lining of the uterus to grow outside the normal location. Look here for more information: