Fear of weight gain is one of the most common reasons women quit taking the pill or decide against using it in the first place. Who wants to take something that might cause you to pack on the pounds?
However, the pill itself does not contain any calories. Most women don't gain weight on the pill, although some experience temporary fluid retention.
If you do gain weight while on the pill, it's likely just a coincidence. The best thing you can do to avoid weight gain, whether you're on or off the pill, is to eat healthily and exercise regularly.