Mild cramping and light spotting are normal early in pregnancy when the fertilized egg implants itself in the uterus. But vaginal bleeding could be a sign of something more serious.
What should I do if I am bleeding?
Call your doctor right away. If you have heavy bleeding or severe pain, go to the emergency room.
Source
First Trimester Bleeding by Mark Deutchman, MD, Amy Tanner Tubay, MD and David K. Turok, MD, MPH (American Family Physician June 01, 2009, http://www.aafp.org/afp/20090601/985.html)
Written by familydoctor.org editorial staff
Reviewed/Updated: 02/11
Created: 10/09