In an average 28 day cycle, a woman is fertile for about two days. Sperm generally survive inside of the woman's body for about 48 hours. They CAN live up to 5 days, but very few make it that long, and the odds of pregnancy from those few remaining sperm are virtually nil, so we'll use the 48 hour life-span as our estimate, since it's more reasonable. Now, this gives the average woman about a three day window period every month for pregnancy to occur. From this alone, the odds of getting pregnant from a one-time sexual encounter are about 11%.

Now, it's estimated that pregnancy only occurs (according to medical websites) about 1/4 to 1/2 of the time that sperm and the egg are present together, due to a variety of reasons. This lowers the odds of pregnancy from a single sexual encounter to about 3-5%. This is why there are so many women who are frusturated because, as hard as they try, they just seem to be unable to conceive.

Now, PLEASE do not use these odds in support of unprotected sex. Many, MANY girls have become pregnant from a single, unprotected sexual act, and in essence you're playing Russian Roulette with your own body. Sure, the odds are in your favor, but it's still a huge risk if you're not ready for a child. To put these odds in perspective, 85% of all couples who have unprotected sex will become pregnant within the first year. And, of course, STDs are always a risk, as well. So please, safe sex only. The odds of both pregnancy and disease might be low, but using protection will prevent STDs and lower the pregnancy odds even further.

Ive got 3 kids the above statement is NOT true. I pulled out every time, she was on the pill, and she STILL got pregnant. M8 i eventually ended up haveing the snip, POTENT STUFF. How old are you? Your probably still shooting Blanks lol .

Yes because someone with three kids is arguing on the Internet with teenagers about pregnancy.

I'm liking your fantasy-reality; it's a shame the real world doesn't work like that.