What can cause vaginal bleeding?

Mother's hormones. When babies are first born, they have been growing in the presence of their mother's female hormones. After birth, the withdrawal of these hormones may cause a little bit of vaginal spotting for a few days, which is entirely normal.
Many possibilities. There are many causes of abnormal vaginal bleeding. This includes medical causes, such as thyroid disorder or hormonal imbalances or undue stress. In addition, physical causes, such as a tear or laceration, polyps, fibroids, or even cancer. This is very dependent on age, medical history, and physical examination.