When Can I Know the Sex of Baby? (And How Will I Find Out?!)

Choosing whether to find out baby’s sex during your pregnancy is a big decision. But for those who want to know ahead of time, the big reveal usually can’t happen fast enough.

When I was pregnant with my first child, my husband and I decided to wait until our wedding anniversary to learn the news. So, the sonogram technician kindly wrote the information on a card for us, and we opened it up together two weeks later. I’m not sure how we both had that level of willpower, but I’m pretty sure I haven’t been that patient since. I’ve learned the sex of my other three children during my pregnancies in different ways, including while getting an ultrasound and even over a phone call.

While learning baby’s sex used to be reserved for the mid-pregnancy anatomy scan, there are now options that allow you to get that exciting news even sooner like the non-invasive prenatal testing (NIPT). So, exactly when can you find out the sex of baby—and how? Read on for the full rundown.

Key Takeaways

• Sex and gender are different: Baby’s sex is determined by things like their reproductive organs, whereas gender isn’t predetermined.
• You can learn baby’s sex as early as 10 weeks. There’s a variety of testing methods, including NIPT, chorionic villus sampling (CVS) and amniocentesis. You can also find out via ultrasound.
• Baby’s sex is determined by the sperm. The egg always contains the X chromosome, while the sperm could contain the Y chromosome (which would make it XY, a male) or the X chromosome (which would make it XX, a female).

Understanding Sex vs. Gender

First and foremost, it’s important to distinguish between sex and gender. Baby’s sex is determined by things like their reproductive organs, chromosomes and hormones. Gender, on the other hand, isn’t predetermined. “Everyone’s gender is unique to them and can be independent of their chromosomal complement,” explains Mark P. Leondires, MD, medical director at Illume Fertility in Connecticut. So the term “gender reveal” is actually inaccurate—though we don’t want to rain on anyone’s parade.

When Can You Know the Sex of Baby?

You can find out baby’s sex as early as 10 weeks of pregnancy. Many people also choose to find out around weeks 18 to 22, at the mid-pregnancy anatomy scan. See below for how long it’ll take you to find out, based on which testing option you choose.

How to Determine the Sex of Baby

If you’re chomping at the bit (and stressing about baby names!), you may want to find out the sex of your little one—you know, before they make their grand entrance into the world. Nowadays, there are many tests that determine baby’s sex. Here are the many ways you can get this intel—and how long you’ll need to wait to get your answer.

IVF/ PGT before implantation

It’s possible to determine the sex of a potential baby before an embryo is transferred during in vitro fertilization (IVF). According to the American College of Obstetricians and Gynecologists, preimplantation genetic testing involves examining an embryo for any possible genetic abnormalities or birth defects. At this time, the chromosome pairing (XX or XY) can also be identified to indicate sex. Preimplantation genetic testing (PGT) can also be used for sex selection during IVF; that means that parents specifically seek out an XX chromosome pairing for a girl or an XY chromosome pairing for a boy, notes CNY Fertility.

What’s the accuracy in sex determination of baby? Since an XX or XY is actively identified, accuracy is around 97 to 98 percent.

When you can you tell the sex of baby? In this scenario, the embryo’s chromosomes are evaluated in anticipation of it being transferred into a mom’s uterus—so sex determination actually happens before pregnancy.

NIPT at 10 weeks

NIPT, also called cell-free DNA testing, is a blood test that’s designed to look for chromosomal abnormalities and conditions in baby, including Down syndrome, trisomy 13 and trisomy 18, says Maura Parker Quinlan, MD, MPH, clinical assistant professor in the Department of Obstetrics and Gynecology at the Northwestern University Feinberg School of Medicine in Chicago. The test analyzes a sample of your blood, looking at tiny fragments of fetal DNA that are released from the placenta into your bloodstream. While the primary purpose of NIPT is to screen for chromosomal abnormalities, Quinlan says, since the test looks at fetal DNA, it also gives parents the opportunity to find out baby’s sex. If it detects a Y chromosome, you’re carrying a boy; if not, you’re expecting a girl.

What’s the accuracy in sex determination of baby? NIPT is 95 to 97 percent accurate, but it isn’t entirely fool-proof, so “there’s always a risk of getting it wrong,” says Jonathan Schaffir, MD, an ob-gyn at the Ohio State University Wexner Medical Center in Columbus, Ohio. Since NIPT is non-invasive, there’s no risk to you or baby.

When can you tell the sex of baby? The test is most reliable starting at 10 weeks of pregnancy, Schaffir says, and results usually take about 10 days.

CVS at 10 weeks

CVS is a test used to diagnose certain chromosomal abnormalities (like Down syndrome) and genetic problems (like cystic fibrosis) in baby. It can be done one of two ways: By inserting a thin plastic tube through your cervix (known as a transcervical CVS) or a needle through your belly (a transabdominal CVS) to reach the placenta and gather a small sample of placental tissue to test. Your doctor will use ultrasound images to help guide the tube or needle to the best spot for sampling. Like NIPT, CVS looks for genetic abnormalities, but it can also reveal baby’s sex through its testing of cells from the placenta.

What’s the accuracy in sex determination of baby? CVS is close to 99 percent accurate at predicting baby’s sex. That said, it is invasive and comes with a small risk of miscarriage (approximately one in 300 to 500 women, with transcervical CVS having a higher risk), so this really isn’t recommended for sex determination alone, explains Christine Greves, MD, an ob-gyn at the Orlando Health Women’s Institute. It’s also not a test that’s used very often anymore, given that noninvasive prenatal testing can accurately predict genetic issues, she adds. However, if you’re already having CVS to detect genetic problems in baby, you can find out whether you’re having a boy or girl in the process.

When you can tell the sex of baby? CVS can be done starting at 10 weeks of pregnancy. After the test is performed, the sample is placed in a dish and sent off to a lab, and it can take about two weeks to get the test results.

Amniocentesis at 15 weeks

Amniocentesis (you may hear it referred to as an “amnio”) is a diagnostic test that’s usually done between 15 and 20 weeks of pregnancy. To do the test, a technician will insert a very thin needle into your amniotic sac to draw a little amniotic fluid. That fluid, which contains cells that baby has shed, is then analyzed to look for genetic abnormalities.

What’s the accuracy in sex determination of baby? “Amnio is considered the ‘gold standard’ for determining information from fetal DNA, including gender, because it’s nearly 100 percent accurate,” Schaffir says. “However, it’s invasive, so there’s a small amount of pain involved and there’s a risk of causing infection or bleeding within the pregnancy sac that could at worst cause miscarriage.” Because of this, amnio isn’t recommended if you’re just trying to find out baby’s sex, given that the test does pose some risk to baby, Quinlan says.

When can you tell the sex of baby? Amniocentesis is typically performed as early as 15 weeks of pregnancy, and results usually take between seven to 10 days, Schaffir says, but could take up to approximately two weeks.

Ultrasound at 18 to 22 weeks

Baby’s external genitals are fully formed by about 13 weeks of gestation, so technically an ultrasound done anytime after that could help determine baby’s sex, Schaffir says. But since all of their anatomical development isn’t complete until around 18 to 22 weeks, that’s usually when the anatomy scan is performed. Unless your little one’s position makes it hard to see, your ultrasound technician can provide a visual confirmation of baby’s sex.

What’s the accuracy in sex determination of baby? “Accuracy is around 97 to 99 percent, depending on the skill of the sonographer and the position of the fetus,” Schaffir says. “So, again, there’s a risk of getting it wrong.”

When can you tell the sex of baby? The results are instant—you can find out baby’s sex in real time during your ultrasound appointment between week 18 and 22 of pregnancy. Better yet, the ultrasound poses no risk to you or baby.

Can you find out baby’s sex at an earlier ultrasound?

It’s possible. Again, around 13 weeks is when baby’s external genitals are fully formed. So you may be able to learn baby’s sex around that time or even sooner via ultrasound, according to Eran Bornstein, MD, vice chair of ob-gyn and director of the Center for Maternal-Fetal Medicine at Northwell Lenox Hill Hospital in New York City.

What Determines the Sex of Baby

It all comes down to sperm, Bornstein says. “Since the egg always contains the X chromosome, if the sperm contains Y chromosome it would be a male (XY),” he explains, “whereas a sperm that contains X chromosome a female (XX).”

To Sum It Up

There’s a lot to navigate when it comes to learning baby’s sex during pregnancy, but your healthcare provider should be able to walk you through it. But if you prefer to wait until the grand finale (or the new beginning, whichever way you want to look at it!), that’s perfectly fine too!

Please note: The Bump and the materials and information it contains are not intended to, and do not constitute, medical or other health advice or diagnosis and should not be used as such. You should always consult with a qualified physician or health professional about your specific circumstances.