This bleeding or spotting is uterine. Therefore, a woman who experiences bleeding in this situation may become niddah.
Time in niddah can often be minimized or avoided, though, by taking precautions in accordance with the laws of stains (e.g., by wearing colored undergarments). For more information on these halachot, please see our articles on stains and toilet paper. Then please get back to us with any follow up questions.