I am going to discuss the actual numbers involved here. Let’s cover the basics first.

What sex acts can lead to pregnancy?
In order for there to be any chance of pregnancy, live sperm has to be inside the vagina.
Thus, you cannot get pregnant from:
-giving a hand job
-being fingered
-oral sex
-anal sex
-dry humping (in clothes or underwear)

Only vaginal intercourse can lead to pregnancy.

Pre-ejaculate from a penis may contain sperm. Medical research has not reached a conclusion on whether or not this is the case, or whether or not the amount of sperm present is enough to have a significant chance of leading to a pregnancy.

If there has been a penis in your vagina, there is a chance you may be pregnant.

Let us now look at what this chance is.


When having unprotected sex at any point in one’s cycle, what is the chance of pregnancy?

Answer: 25%.

Women under the age of 25 have a 25% chance of conception occurring in each cycle.

(At 25, this chance drops to 15%; past 40, it drops to a mere 5%.)

This means that it normally takes four to five months for conception to occur if you and your partner are in optimum health and are having sex on a regular basis. Thus, if you have unprotected sex (even just once), you have a one in four chance of getting pregnant.

What are the chances of having unprotected sex while fertile?

Answer: between 3% and 11%.

Assuming you have a perfectly regular 28 day cycle (not many of us do), you will be fertile for around two days while the egg is traveling down the Fallopian tubes. Sperm can live, on average, for two days in your vagina and uterus.

So, the chance of randomly having sex within that time frame is around 3/28 or 11%.

When egg and sperm meet, pregnancy occurs only 25% of the time. So this number is actually more around 3%.

Why is this the case?

The reasons that we become pregnant only once out of four times when having sex during our fertile time are many. The sperm can get lost and never find the egg. We also know that the egg is not the passive recipient that was thought in the past; the egg actually has defences that can be used to thwart a sperm. So, just as you may turn a guy down, the egg may refuse a sperm; we know little of how this decision is made by the egg. Alternately (and this is quite common) fertilization may take place but be rejected by your body because it is a “defective pregnancy”. Many pregnancies are rejected (miscarried, spontaneously aborted) without our even knowing our egg was fertilized. Source

Well, those sound like good odds…

If, with these chances you have perfectly random unprotected sex 20 times, you have a more than fifty-fifty chance of becoming pregnant. Put another way, if twenty women at your school/work have unprotected sex on any given day, there is a 50 percent chance that someone will become pregnant. Source

What are the chances of getting pregnant on different forms of birth control?



Rates of effectiveness for birth control are based on 100 women having sex for a year. So 4% means 4 women out of 100 would get pregnant while using that method for one year.

Based on where you find these statistics, the numbers for the “less effective” group will vary by around 5%.

What is “typical use” and “perfect use”?
Perfect use means just that – the method is used perfectly. The instructions are followed perfectly (you take the pill at the same time every day, you put the condom on correctly) and used every time.

Typical use allows for failures that, like it or not, we all make. This includes, but is not limited to: misreading directions, incorrect application, missing a pill/shot or forgetting to put on a condom, a condom breaking, being unable to fill a prescription, or receiving incorrect information.

I want a more detailed comparison!
Go here.

I read this, but I still think I have a very unusual scenario that I need to post about on the boards.
You don’t.
If you think you are pregnant, the ONLY way you will know if you are or not is to take a test. We can’t tell you, and all you’re going to get is a bunch of people saying “We don’t know, take a test.”

When can I take a pregnancy test?
One week after your missed period. Using early response tests, the earliest you can take a test is five days before your missed period. As a sidenote, if you go to Planned Parenthood/the ER/a doctor’s office, they are going to give you a urine test just like the one you buy at a drug store. (In other words: there are not many false positives and the Nile is not just a river in Egypt.)

No, but really…. AM I PREGNANT??
Please refer to these handy-dandy chart, created by the awesomeness that is Sumayah.



Sources
www.thebabycorner.com . . .
www.sexinfo101.com . . .
www.plannedparenthood.org . . .
en.wikipedia.org . . .
my big fat brain
Sumayah's awesomeness
your mom