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Hormonal contraceptives start being effective in giving you protection after about 3-4 weeks of use. Usually you start having complete protection after you have had a withdrawal bleed and have started with your next pack. You should have considered using additional protection/back-up form of contraception to remain protected against pregnancy. Chances of pregnancy cannot be ruled out. Look out for development of any other new symptoms suggestive of pregnancy. Stop the pill use if you suspect to be pregnant. Visit your doctor/gynecologist for examination and tests to rule out pregnancy before you start with next pill pack.
Take care.