It is possible for women to mistake implantation bleeding that occurs within 12 days of conception for a light period, according to WebMD. Implantation bleeding happens when the fertilized egg attaches itself to the uterine lining. It is important for women with abnormal bleeding to consult with a physician.
The Mayo Clinic explains that delayed periods can signify pregnancy, but they can also be caused by weight loss, eating disorders or premature ovarian failure, a condition that occurs in women under the age of 40. Due to the fact that light bleeding and cramping are not telltale signs of pregnancy, it is always best for any woman who is concerned she might be pregnant to take a home pregnancy test and follow up with a physician if the test is positive.