Implantation bleeding

Implantation bleeding is typically a small amount of vaginal bleeding that occurs in early pregnancy due to the fertilized egg attaching to the inside of the uterus.^{[1] [1]}

References

1. 1 2 editor, Eyal Sheiner, (2011). Bleeding during pregnancy a comprehensive guide. New York: Springer. p. 9. ISBN 9781441998101.