When and How Can You Find Out Your Baby’s Sex?

With that said, not all sex determination methods are appropriate for all pregnancies. Keep reading to learn about your options and how early you can find out your baby’s sex.

Your baby’s sex is determined from the moment of conception. Although babies take DNA from both partners, the father’s genes dictate the baby’s sex. 1

Humans typically have 46 chromosomes, which come in pairs. Two of them are sex chromosomes. Females usually have two X chromosomes, and males have one X and one Y chromosome. 2

Every egg cell contains one X chromosome. Sperm cells, on the other hand, can carry either an X or Y sex. The type of chromosome carried by the sperm cell that fertilizes the egg will determine the baby’s gender. 3

What about intersex babies?

The picture we just painted is slightly simplified. You may have heard of intersex people, who often have more complicated chromosomal situations leading to sexual characteristics that make it hard to categorize them as “male” or “female.”

For instance, some intersex people have the external genitalia of one sex, but internal structures that are more like the other (e.g., they possess a penis as well as ovaries and a uterus).

There are many conditions that can cause this, not just one. There’s some controversy around which conditions should be considered genuinely intersex; depending on how broad the definition is, anywhere between 2 in 10,000 (0.018%) and 1.7% in 100 (nearly 1 in 50) babies are born this way. 4

While your baby’s sex is set at the moment of fertilization, you’ll typically have to wait until at least the end of the first trimester to see the signs you’re having a boy or girl. You’ll usually find out via genetic screening or an ultrasound.

Here are the main methods that reveal your baby’s sex:

1. Non-invasive prenatal testing (NIPT)

This is also known as cell-free DNA screening (cfDNA) or noninvasive prenatal screening (NIPS). It’s a blood test that analyzes placental cell DNA (which is identical to your fetus’s DNA) in your bloodstream. 5

With this screening, doctors can detect early on if your baby might have chromosomal disorders like Down syndrome, trisomy 18, or trisomy 13. Since NIPT checks your baby’s chromosomes, it can also determine her sex.

You can get the screening as early as 10 weeks of pregnancy. It has an accuracy rate of 98%–99%.

Only moms with single or twin pregnancies can take the test. You can’t take the test if you’re carrying three or more babies. 6

2. Chorionic villus sampling (CVS)

Chorionic villus sampling (CVS) is another prenatal genetic test that looks for chromosome disorders. 7 It works by taking and analyzing chorionic villus cells from your placenta. Since these cells have the same chromosomes as your baby, they’ll reveal her sex.

You can take the CVS test between weeks 10 to 13 of your pregnancy. While it’s very accurate, it’s an invasive test that comes with certain risks, including infection, bleeding, and miscarriage (in rare cases), so your doctor will only assign it if it’s medically necessary. They won’t test you just to check your baby’s sex. 7

3. Amniocentesis

Amniocentesis, or an amniotic fluid test, is another diagnostic test that doctors can use to screen for potential birth defects, as well as infection.

Your baby is wrapped in an amniotic sac in your womb. The fluid in the sac contains your baby’s cells, which show her genetic makeup and sex. To test this amniotic fluid, your doctor will insert a long needle into your belly and womb. They’ll monitor your baby with an ultrasound during the procedure.

Doctors typically conduct this test between weeks 15 and 20 of pregnancy. 8 It’s able to determine fetal sex with a high degree of confidence. 9 However, like CVS, this is an invasive procedure that you’ll only undergo if it’s medically necessary.

4. Ultrasound

An ultrasound creates images of your baby in the womb with sound waves. It lets your doctor check on her development. 10 When you go in for an ultrasound, your doctor will spread some gel on your belly and use a handheld probe to move around it.

Most women get an ultrasound called the anatomy or gender scan between 18 and 22 weeks pregnant. By this point, most babies are developed enough to determine their sex just by looking at their genitals, which means this is when many moms find out whether they’re having a boy or girl. 11

Because this test relies on line of sight, if your baby doesn’t feel like cooperating, it’s possible you won’t be able to see her sex the way you were expecting when you get the anatomy scan. If so, you’ll just have to wait for a few more weeks until your next ultrasound.

5. Preimplantation genetic diagnosis (PGD)

Preimplantation genetic diagnosis (PGD) isn’t applicable to all pregnancies. PGD is for couples trying to get pregnant through assisted reproductive techniques, such as in vitro fertilization (IVF). The procedure reduces the risk of having an unhealthy baby. 12

Your doctor will take and test cells from the embryos you’re using for genetic disorders before transferring them to your uterus. They won’t implant any that come back positive.

The primary purpose of PGD is to test for genetic disorders, but it can also tell the baby’s sex.

With this method, you can find out the sex of your baby even before you technically become pregnant. In fact, while this is somewhat controversial, some parents use this as a chance to select the sex of their baby.

There are a lot of folk beliefs that certain pregnancy symptoms can correspond to the sex of your baby. Often, the idea is that if your symptoms are worse (e.g., you have stronger nausea or wilder mood swings), you’re having a girl.

Similarly, many people believe that the side of your uterus that your placenta develops on provides a hint as to your baby’s sex (this belief, which is known as the Ramzi theory, popped up on the internet several years back).

Unfortunately, all of these beliefs lack scientific validity. There just isn’t any evidence for any of them. They’re able to persist because parents who use them end up being right 50% of the time, but the research suggests these “correct” predictions are almost certainly just coincidences.

There are home gender prediction tests that claim to reveal your baby’s sex via a simple urine or blood sample.

Before you grab your purse, know that experts don’t think urine-based tests are reliable, as your urine doesn’t contain any genetic information that’s linked to your baby’s sex. If you take one of these tests, treat it purely as entertainment and don’t put any stock in the result.

Blood tests are on firmer footing, at least theoretically—as mentioned, NIPT works by taking a blood sample—but these at-home kits aren’t regulated by major medical organizations like the FDA, and there’s no guarantee the test you get will be legitimate.

If you’re curious enough to try out a gender prediction test for fun, run it by your doctor first. If they approve it, be sure to follow the safety instructions, and don’t expect the results to be that accurate.

While you may be desperate to start planning your gender reveal party, if you got pregnant relatively recently, you may have to wait a while before you stock up on those pink or blue balloons.

Talk to your doctor about your options. Depending on your situation, you might be able to find out your baby’s sex as early as the first trimester—but if none of the early tests we mentioned are right for you, you’ll just have to be a little patient.