Hello dear I understand your concern If you have normal and regular period then no chance of pregnancy. But if you have sexual intercourse int he fertile period of cycle when you are not on the active pill then pregnancy is possible. Regular use of birth control pill and regular period does not cause pregnancy. Cardinal sign of pregnancy is the missed period. Weight gain in the abdomen area may be aside effect of the birth control pill. Do regular exercise like walking and yoga, avoid saturated fat and oily food. Take healthy diet: more fresh fruits and green leafy vegetables. Drink plenty of water Hope this may help you Contact HCM for further health query. Best regards Dr. Sagar