Everything you need to know about pregnancy

Pregnancy is possible any time sperm has a chance to meet up with an egg. That can happen if you’re having sex and not using birth control, including condoms, and sperm gets inside the vagina or onto the vulva, where it can then travel into the vagina. (Pregnancy can also happen if you’re using birth control, but it is much less likely.) Typically, pregnancy happens when someone with a penis ejaculates into the vagina or onto the vulva of another person. Ejaculation is when semen, a whitish fluid containing sperm, comes out of the penis.

How likely you are to get pregnant from having sex without using birth control depends on where you are in your cycle when you have sex.

Why does it matter where you are in the menstrual cycle?

To understand why it matters where you are in the menstrual cycle when you have sex without birth control, it helps to understand how the menstrual cycle works. Every new menstrual cycle starts with your period. Day one of your period is day one of that cycle. An average cycle, from the first day of your period to the day before your next period, is 28 days, but it can be longer or shorter and still be considered normal. You can only get pregnant from penis-in-vagina sex on six days during your menstrual cycle—the five days before you ovulate and the 24 hours after ovulation. These are your fertile days. If you have an average menstrual cycle, you usually ovulate in the middle of your cycle.

The problem is that you can’t know for sure exactly when you’re ovulating, especially if you don’t have a regular menstrual cycle (more on that later). And sperm can live inside your body for up to 5 days, whether or not you’re on your period. That means if you ovulate today, you could get pregnant from sex you had up to 5 days ago. So if you’re going to have penis-in-vagina sex, no matter where you are in your cycle, your best bet for preventing pregnancy is to use some form of birth control, like the pill, condoms, an IUD, the pull-out method, emergency contraception (EC), or any one (or more!) of your many other choices.

What is a regular menstrual cycle?

A regular menstrual cycle is one that comes at about the same time each month. It’s normal for most people with a uterus to have cycles lasting between 21 and 35 days, but having a regular menstrual cycle means that your cycle is between 26 and 32 days long. If your menstrual cycle is regular, your cycles are close to the same length every month, and ovulation happens on approximately the same day every cycle. If you have a regular, 28-day cycle, ovulation is most likely happening in the middle of your cycle, between days 12 and 16.

Here’s how to figure out long your menstrual cycle is:

• Step 1: Start by counting the first day that your period begins as day one.
• Step 2: Count each day after that until you get your period again, which is day one of the next cycle. So the first day of your period until the last day before your next period is one menstrual cycle.
• Step 3: Start over with day one to count the next cycle. That’s it!

If you count the number of days in each cycle for a few cycles, and all your periods are between 26 and 32 days, then you have a regular period. Not every cycle has to be the exact same number of days—it’s normal for it to be a few days longer or shorter from month to month.  As long as it’s between 26 and 32 days long, your cycle is considered regular.

Your menstrual cycle is considered irregular if it is less than 26 days or more than 32 days long more than twice a year, but if it’s between 21 days and 35 days, it could still be normal; it’s just not regular. If two or more months go by and you don’t have a period, that’s also considered an irregular menstrual cycle (or it may be a sign that you are pregnant).

How do I know when I’m ovulating?

If you’ve counted the length of a few cycles, and your cycle is regular, there are a few different ways that you can estimate when you’re ovulating. You can track what day of your menstrual cycle you’re on, check your cervical mucus, track your body temperature, and/or monitor your hormone levels. Your best bet for preventing pregnancy by monitoring your ovulation is to use more than one of these ways to estimate when you’re ovulating.

Tracking your menstrual cycles and paying close attention to your signs of fertility to predict ovulation and then avoiding sex without using another form of birth control (like condoms or a diaphragm) on those days is a type of birth control called fertility awareness. It can be effective at preventing pregnancy, but it’s not the most effective birth control option out there. Typically, about one in four people using this method will get pregnant within a year of using it.

If your cycle is irregular though, it will be hard to predict when you are ovulating, and mistakes are likely to happen—meaning that at some point, it’s likely you will think you’re not ovulating when you are. Using a birth control method other than one of the fertility awareness methods, like condoms or the pill, is going to be a more effective way to prevent pregnancy.

Can I get pregnant during my period?

The short answer is YES! If your menstrual cycle is regular, you are much less likely to get pregnant while on your period than if your menstrual cycle is irregular—but that doesn’t mean it’s impossible even with a regular cycle.

How soon can you test for a pregnancy after sex?

Pregnancy doesn’t start the moment you have unprotected sex. In fact, it doesn’t start until a fertilized egg implants in the lining of your uterus, which takes about a week. So it doesn’t work to take a pregnancy test the day after you had sex.

Once implantation occurs, your body begins making a pregnancy hormone called human chorionic gonadotropin (hCG). Home pregnancy tests measure hCG in urine to determine if you’re pregnant. Clinics can measure hCG in urine or in a blood sample. It takes up to two weeks after having sex for there to be enough hCG to measure with any test.

So you have to wait for about two weeks after having sex to get an accurate pregnancy test result.

It’s too early for a pregnancy test…but is it too late for EC?

If you’ve had sex in the last five days and don’t want to be pregnant, you can use emergency contraception (EC) right now. EC prevents ovulation and thus prevents pregnancy before it starts (which means that EC is not the same thing as abortion pills). There are a two types of EC pills and two IUDs that work as EC. EC pills can be effective if you take them up to five days after sex, but they are more effective the sooner you take them. The IUDs that work as EC are equally effective no matter when in those five days you get one, but you’ll need to see a provider in person to do so. Tell them it’s for EC so they can get you scheduled asap.

What if I’m pregnant and don’t want to be?

Abortion is when you end a pregnancy on purpose, either with the abortion pill or with an abortion procedure. If you want to get an abortion, check out AbortionFinder to find a provider.