Does the birth control pill make you gain weight or become infertile? i am 18 and have been on it for 3-4 years

Oral contraceptives: Birth control pills are designed to stop ovarian function temporarily and hence there effects are reversible even after long term use including fertility though it may take a few cycles unless there are underlying issues at the time bcp were initiated regards weight gain they do have a high level of estrogen which can cause fluid retention despite myths there should not be a gain of more than few.