thanks for your query.
There could be the following possibilities :
1. Common occurrence with oral contraceptive pills
, particularly in the first month of use.
2. Possibility of a pregnancy
, which is also common during the first cycle of use.
3. Irregular cycles due to complication of abortion, such as infection, adhesions, endometrial damage etc.
4. Stress, anxiety, weight changes, travelling, fever, surgery, illness, ingestion of other medications that reduce efficiency of birth control pills.
5. Polycystic ovaries
, thyroid dysfunction
Please consult your gynecologist to know which of these is the real cause.