I had sex with my boyfriend the 3rd day of my period... I took a day after pill one hour later, would my period go away if I was pregnant?

1. Always assume you are fertile;
2. That in mind, you are actually fertile within a certain window of time around ovulation, which is supposed to happen once every 28 days. This is not generally when you have your period;
3. Some women bleed when they ovulate, so you can't rely for sure on timing and need another form of birth control;
4. That said, you probably are not pregnant;
5. If a pregnancy resulted from this incident, your period would not immediately stop. It doesn't work that way. The egg and sperm both travel through your body, and into the uterus, then implant and this does not happen instantaneously, so you can't go by whether your period continues.
If you miss your next one, take a pregnancy test. I'm not sure what the timing is for day-after pills and whether they are effective just one hour after intercourse... did you read the package insert on when to take it? If not, call a pharmacist and ask.

You are probably not pregnant but better either stop having sex or start using reliable birth control - it sounds like you are playing with fire.

Odds are in your favour that you are not pregnant. While it can happen, ovulation usually doesn't occur early enough in a cycle for you to become pregnant from sex on the third day. That you took the morning after pill also lowers the risk.

However, as dontknownuthin said, no sense in taking any chances as there are no guaranteed safe times. Use reliable birth control every time you engage in sex, preferably two forms of birth control, or refrain from having sex until you are in a position where you could provide for an unplanned pregnancy.

Also, keep in mind that you would not want to rely on the morning after pills on a regular basis. They are high dose pills and are meant for emergencies, such as failure of a current contraception method.

Because you took the morning after pill, you may find your cycle gets a bit off. You may have some bleeding when you don't expect to. See what happens when your next period is due.

Most likely you were not pregnant and if you were the morning after pill ( I will assume that was what the pill was, not just a normal birth control pill)

But remember the morning after is for emergency, not use all the time, so if you are going to be having sex, please start using at least two methods of regular birth control.

Also remember that the morning after pill will effect your cycle, so you can expect your next couple of periods to be off

And one other thing - one form of contraception MUST be a condom because nothing else prevents the spread of sexually transmitted diseases like HIV/AIDS, Heptatitis and many others. But condoms are notoriously unreliable as they break or can fall off, particularly with less experienced users and the other form should be something highly reliable - talk to your doctor. And if you take any type of prescription, do not smoke - serious risks are associated with combining smoking and birth control.