You can avoid pregnancy by not having sex or using both condoms and birth control every time you have sex.
Emergency contraception (the morning-after pill) can prevent pregnancy up to five days AFTER unprotected sex.
How do you get pregnant?
Here's what CAN cause pregnancy: semen (ejaculate) or pre-ejaculate (pre-cum ) getting inside the vagina. Most often, this happens from vaginal sex (penis-in-vagina). Less often, it happens when semen gets on the vulva.
Semen comes out of the penis during orgasm, and it's chock full of sperm. Pre-ejaculate (pre-cum) is a much smaller amount of fluid (usually just a few drops) that's sometimes released from the penis before and during sex. It's usually such a small amount that it can be hard to tell if any has come out, but it can have a little bit of sperm in it. The chance of getting pregnant from pre-cum is much less than the chance of getting pregnant from semen, but it still might be possible.
Since guys can't control when pre-cum comes out, and it can happen anytime, you need to put on a condom BEFORE you start having sex and wear it the entire time.
Here's what CAN'T cause pregnancy (unless sperm somehow comes into contact with the vagina or vulva):
Pregnancy can also happen with the aid of doctors and fertility treatments, like IVF and alternative insemination. People may choose these treatments if they have health conditions that make getting pregnant more difficult, because they are single, because they are in a relationship with another woman, or lots of other reasons. Learn more about fertility treatments.
How can I avoid pregnancy?
There are two ways to avoid pregnancy:
Don't have sex.
Use both a condom AND birth control every time (and the entire time) you have sex.
Can I get pregnant if his penis gets near my vagina but not in it?
Pregnancy can happen when sperm (from cum or pre-cum) gets in the vagina or on the vulva. This usually happens when two people have vaginal (penis-in-vagina) sex.
If sperm comes in contact with the vagina or vulva during body rubbing/dry humping without clothes, there’s a small chance of pregnancy (even if you don't actually have his penis in your vagina).
If you’re concerned about the risk of pregnancy, use birth control like the pill or IUD. And use condoms along with the birth control to reduce the risk of STDs.
If you’re thinking about having vaginal sex, talk about what kind of birth control you want to use with your boyfriend/girlfriend. It’s also a good idea to talk with a parent or another trusted adult, and then visit a doctor, nurse, or health care provider to choose a method and get on birth control. The staff at your local Planned Parenthood health center can help. You can also take our quiz to find out what method of birth control may be best for you.
Can I get pregnant only at certain times of the month?
There are certain times of the month when it’s more likely that you’ll get pregnant from having sex. But, it’s possible to get pregnant anytime you have unprotected vaginal (penis-in-vagina) sex.
Even if you’re on your period, about to get your period, or just had your period, it’s possible to get pregnant from unprotected sex. It’s even possible to get pregnant before you have your first period. And the number of times you’ve had sex doesn’t matter either: whether it’s your first time having sex or the 100th time, you could get pregnant.
So having vaginal sex — at any time — means you need to make choices about birth control and preventing STDs.
How long does it take to get pregnant after sex?
Pregnancy doesn't start the moment a penis ejaculates in a vagina. It can take up to six whole days for the sperm and egg to join and form a fertilized egg. During these six days, sperm are hanging out in the reproductive organs, waiting for an egg to show up.
But since sperm swims through the vagina up to organs deep in your body, you can’t avoid pregnancy by trying to wash out the sperm. Once they’re in there, there’s no catching them.
Then, it takes another six to ten days for the fertilized egg to attach itself to the lining of the uterus. Pregnancy begins once all this happens.
If you’re concerned about unintended pregnancy after having unprotected vaginal sex, you may want to consider emergency contraception (EC), also known as the morning-after pill. EC prevents pregnancy AFTER unprotected sex. EC is not the same thing as the abortion pill, and it will not work if you’re already pregnant.
EC only works if you take it within 120 hours (5 days) after unprotected sex. And the sooner you take it, the better.
Should I take the morning-after pill (emergency contraception)?
If you had vaginal sex in the last five days and did not use a condom or birth control or if the condom broke or slipped off, you should use emergency contraception if you do not want to get pregnant. It prevents pregnancy after unprotected sex, but it does not end a pregnancy (cause an abortion).
It is effective if started within 120 hours (5 days) after unprotected sex. The sooner you take it, the better it works.
Plan B One-Step is a brand that’s available in the family planning aisle (where the condoms are) of many drugstores. Anyone can buy it, no matter how old you are. Other brands of EC, like Next Choice One Step, are available without prescription at many pharmacies for anyone 17 or over. Teens under 17 can still get these other brands of EC with a prescription.
Missing your period after having unprotected sex is the biggest sign that you might be pregnant. If your period is late, take a pregnancy test.
But there are a lot of things besides pregnancy that can cause a late or missed period, including stress, illness, not eating enough, too much exercise, or using a birth control method that contains hormones. Having a period that comes later than usual or missing a period is pretty common in teens, because it can take a few years for your cycle to become regular.
So the only way to know for sure if you're pregnant is to take a pregnancy test. You can get a pregnancy test at a drugstore or health center. At-home pregnancy tests are 99 percent accurate when taken after a missed period.
- See more at: http://www.plannedparenthood.org/teens/sex/how-pregnancy-happens#sthash.zeh847kf.dpuf