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Korin Miller

When (and How) You Can Find Out Baby's Sex

Learning whether you’re having a boy or girl is a major pregnancy milestone. Here’s when you can expect to hear the big news, and how.

If you’ve decided to find out baby’s sex during your pregnancy, the news probably can’t come soon enough. After all, it’s a huge moment in your prenatal experience, when you can envision life as the parent of a little boy or girl. While it used to be that learning baby’s sex was reserved for the anatomy scan around 20 weeks of pregnancy, there are now some options for finding out way sooner. So how and when can you find out the sex of the baby? Keep reading.

1. Non-Invasive Prenatal Testing

Non-invasive prenatal testing (NIPT), also called cell-free DNA testing, is a newer blood test that’s designed to look for chromosomal abnormalities and conditions in baby, including Down syndrome, trisomy 13 and trisomy 18, says Maura Quinlan, MD, MPH, an 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.

Accuracy: NIPT is 95 to 97 percent accurate, but it isn’t entirely fool-proof, so “there is 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. Cost is generally the biggest drawback of this test, since some insurances don’t cover it, Quinlan says.

When you can get results: The test is most reliable starting at 10 weeks of pregnancy, Schaffir says, and results usually take about 10 days.

2. Chorionic Villus Sampling

Chorionic villus sampling (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.

Accuracy: CVS is close to 99 percent accurate at predicting baby’s gender. That said, it is invasive and comes with a risk of miscarriage (in up to one in 100 women, with transcervical CVS having a higher risk), so this really isn’t recommended for gender prediction alone, says Christine Greves, MD, an ob-gyn at the Winnie Palmer Hospital for Women & Babies in Orlando, Florida. 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 get results: 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.

3. Amniocentesis

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.

Accuracy: “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 is invasive, so there’s a small amount of pain involved and there is a risk of causing infection or bleeding within the pregnancy sac that could at worst cause miscarriage.” Because of this, amnio is not 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 you can get results: Amniocentesis is typically performed as early as 15 weeks of pregnancy, and results usually take between seven to 10 days, Schaffir says.

4. Ultrasound

Baby’s external genitals are fully formed by about 14 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 20 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.

Accuracy: “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 is a risk of getting it wrong.”

When you can get results: The results are instant—you can find out baby’s sex in real time during your ultrasound appointment. Plus, the ultrasound poses no risk to you or baby.

5. Home Gender Predictor Test Kit

You may have spotted these at your local drugstore and wondered what they were all about. They vary, both in how they work and how accurate they are. Some test urine while others test blood. But across the board, they’re not sanctioned by any major medical organization.

Accuracy: “There are some completely baseless tests out there that claim to determine gender based on maternal urine, and they’re very unreliable,” Schaffir says. Others have you collect a blood sample and mail it in for a DNA test. “Since these are mailed to laboratories of uncertain reputation that may or may not have gone through the certification process needed to prove their reliability, the results may or may not be accurate,” he says. “I’d say it’s better to go through a lab recommended by your prenatal care provider.” Quinlan agrees: “They’re not FDA-approved. I wouldn’t rely on the results.”

When you can get the results: How quickly you can get results varies based on what kind of gender predictor test you use, but some, like the SneakPeek Early Gender DNA Test, promise to give you results in less than 72 hours after you place your order. Remember, these aren’t FDA-approved and it’s hard to say how reliable they actually are.

In general, doctors say the anatomy scan and non-invasive prenatal testing are the best, most reliable and safest options for determining baby’s sex. If you’re not sure what you want to do, talk to your doctor, who’ll be able to guide you.

Updated April 2019

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