How Soon After Sex Can I Know If I’m Pregnant?
If you’ve had unprotected sex or a contraception “fail”, you might be wondering whether you could be pregnant. It’s important to understand the facts about ovulation and fertilization, as well as be informed about emergency contraception, or the “Plan B” pill.
Once you start menstruating, about every month, a mature egg within one of your ovaries is released into the fallopian tube. This process is called ovulation. The egg can survive in the fallopian tube for about 24 hours. Fertilization happens when, about 20 minutes after sexual intercourse, a single sperm (from the 150 million released) successfully fertilizes the egg cell and creates a zygote. About a week later, the fertilized egg has made its way down the fallopian tube and into the uterus. Implantation happens if the fertilized egg attaches itself to the lining of the uterus.
Did you know that you can get pregnant on a day you didn’t have sex?
The “ovulation window” is tricky to pin down. Women’s monthly cycles are typically between 28-32 days, measuring from the first day of their period to the first day of their next period. Most women ovulate anywhere from Day 11 to Day 21 of their cycle. It’s important to note that under the right conditions, sperm can survive inside a woman’s reproductive tract for as long as five days after sexual intercourse. So even if you had sex outside your “ovulation window”, there is still a chance you can be pregnant.
What about the “Plan B” pill?
The morning-after pill is considered an “emergency contraceptive” and is often taken within the 3 days after unprotected sex or a contraceptive failure (like a condom tear) to prevent pregnancy. The “Plan B” pill may prevent ovulation, prevent sperm from reaching the egg, or irritate the lining of your uterus making it difficult for an embryo to implant. There are side effects with taking the pill and it’s important to know that the morning-after pill does not end ectopic pregnancy. This is when an embryo implants outside the uterus and is a serious condition that requires immediate medical attention. The morning-after pill also doesn’t guarantee that you won’t get pregnant, and it doesn’t protect you from HIV or other sexually-transmitted diseases.
When should I take a pregnancy test?
A missed period is usually one of the first signs of a possible pregnancy. Pregnancy tests measure the hCG hormone, which is only present in a woman’s body after fertilization. Since conception, or the fertilization process, happens about two weeks before your period, and it takes about two weeks for your hCG levels to be high enough to be detected in urine, you can take a pregnancy test one day after a missed period, though the FDA recommends waiting for 1-2 weeks “for most reliable results”. It’s also important to note that a missed period is not always a sign of pregnancy. Read more about that here.
If you think you might be pregnant, reach out to your local pregnancy resource center! We are here to listen and help you without judgement. We are here for you!