Thanks for your query on the portal.
If the proper storage temperature specified on the pack is not maintained, it is possible that the pills would not produce desired effect.
Also, sometimes, if your body weight is high, the pills might be of a lesser dose than you require, causing breakthrough bleeding
Plus, abnormal bleeding , even if on pills, requires investigation, as it might point to an unintentional pregnancy
or other pathologies.
Please consult your healthcare provider.