The "pill" is a type of hormonal birth control
that is very effective at preventing pregnancy. The hormones in the pill act to prevent the ovaries from releasing an egg (known as an ovulation) in between your periods. Without an egg released from the ovaries, pregnancy cannot occur. Despite its near 100% theoretical effectiveness, some women still get pregnancy while on the pill.
Much of the time when a women gets pregnant while on the pill, there is a specific reason why it failed. The most common reason that a women on the pill would get pregnant is a missed pill. If you sometimes forget to take the pill, or if you don't take it at the same time every day, then the effectiveness of it drops. This is true if you forget just one pill. Another reason why the pill fails sometimes is that other medications that you may be taking can reduce its effectiveness. The most well know medications are certain antibiotics, but they are not the only ones.
I suggest that you schedule an appointment with your OBGYN or primary care physician
, whoever you see to get your birth control prescriptions. He or she can discuss the importance of safe sex (with condoms) even when you are on the pill to prevent STDs. If you are having trouble remembering your pill, you can discuss other forms of hormonal birth control that do not require you to remember a pill every day.