Help! Could I be Pregnant?
At SexInfo, we answer a lot of questions about whether or not a woman could be pregnant due to a variety of different situations. For examples, check out our Pregnancy FAQs or our Pregnancy Q&As. The frequency of these questions has demonstrated to us that we need to clearly spell out what has to happen for a woman to become pregnant. This article summarizes the key points, and then provides more information about those points. Much of the information in this article will overlap with our FAQs and Q&As, but we have put all of the relevant information into one article in an effort to provide a clear outline of how a woman can become pregnant. This article does not contain information about in vitro fertilization or surrogate mothers; it is directed towards those who wish to avoid pregnancy.
There are four things that need to happen for a woman to become pregnant. If all of these things happen, through any means, then the woman is pregnant:
- Sperm enter the vagina,
- where they swim through the cervix and uterus into the fallopian tubes,
- where one sperm meets an egg and fertilizes it (this is called conception),
- then the fertilized egg travels to the uterus and implants itself into the uterine wall.
Step 1: Sperm enter the vagina
**Note: please see the Anatomy section for more information about the different parts of the male and female body.**
- If sperm enter the vagina, then they are in a position to complete the other three steps.
- If they only reach the vulva (the outer genital area), they can still swim up to the vagina and continue on. However, this is much more difficult, so the chance of pregnancy is much smaller.
- Cowper's gland secretions (also known as precum) can also carry sperm, so precum can cause a pregnancy. This is one reason why the withdrawal method is not very effective.
- It is possible (but unlikely) for sperm to travel through thin clothing (like underwear), but they cannot travel through thicker clothing (like jeans). Multiple layers of thin clothing (like underwear and pajama bottoms or both partners wearing underwear) also can stop sperm.
- Sperm have a very difficult time traveling through water, so if the man ejaculates into the water of a bathtub or shower, away from the woman's vulva, pregnancy is very unlikely. However, sexual intercourse in a pool or a bathtub is not an effective way to stop sperm. If the man ejaculates into the vagina or even on the vulva while in water, there chance of pregnancy is just as high as in the corresponding activity in dry air.
- The best way to keep sperm from entering the vagina is to use a condom.
Step 2: Sperm swim through the cervix and uterus into the fallopian tubes.
- Once sperm are in the vagina, they can swim through the cervix, uterus, and fallopian tubes. The more sperm that enter the vagina, the greater the chance of pregnancy.
- Certain birth control methods interfere with the sperm's ability to enter the cervix and continue on.
- Hormonal methods like the pill or the shot change the cervical mucous, which makes it harder for the sperm to pass through the cervix.
- Emergency contraception pills (also called the "morning-after pill" or Plan B) also interfere with the sperm entering the fallopian tubes.
- Barrier methods like the diaphragm or the cervical cap create a physical obstruction, which is why they are called barrier methods.
Step 3: One sperm meets an egg and fertilizes it, which is called the moment of conception.
- There has to be an egg in the outer third of a fallopian tube for the woman to become pregnant.
- A woman has to ovulate shortly before or after intercourse to become pregnant.
- Sperm can live for up to five days in the woman's body, so if intercourse happens even a few days before ovulation, a sperm could still be present to fertilize the egg.
- An egg can live for about one to two days, so intercourse after ovulation can still result in pregnancy.
- A woman can ovulate before she has her first period, so intercourse before menarche (when the woman has her first period) can result in pregnancy.
- Virginity has nothing to do with ovulation, thus a virgin can get pregnant her first time just as easily as her 100th time.
- Many hormonal birth control methods like the pill or the shot inhibit ovulation, so an egg is not available to fertilize.
- Emergency contraception pills also inhibit ovulation.
Step 4: The egg implants itself into the uterine wall, which is the start of pregnancy.
- A fertilized egg travels down the fallopian tubes and may succeed in implanting into the uterine wall.
- Many hormonal birth control methods like the pill or the shot change the uterine lining, making it inhospitable to the fertilized egg (meaning the conceptus won't have a place to implant and grow).
- Emergency contraception pills also make the uterine lining inhospitabletion to implant.
If you now read the FAQs on pregnancy or the Q&As on pregnancy, you will see how the information in this section helps answer most of the pregnancy questions.