Thanks for the query.
it is unlikely that this could be due to a pregnancy as the bleeding has occurred during the expected period date, one day early is still acceptable.
However, since the bleeding was only for a day, we need to rule out causes like anemia, thyroid disorders, stress, hormonal imbalance, etc.
However, you can get a pregnancy test done to be reassured.
Consult a gynecologist for treatment and investigations.
Hope this helped.
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