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When Can You Find Out the Sex of Your Baby?

Learn how accurate these tests are to predict the sex of your baby and determine if you're having a baby girl or baby boy.
Finding Out the Sex of Your Baby
Updated: September 8, 2023
Medically reviewed by  Breanna Herring, CNM, ARNP, MSN, DNP
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Are you excited to know the sex of your baby? 

When a person finds out they are pregnant, they may immediately want to know whether they are having a baby girl or a baby boy. While some pregnant people wait until their due date to find out the baby's sex, more tend to find out the baby's gender well before their little one enters the world.

One Harvard Medical School study found that 58% of expecting parents found out or intended to find out the sex of their baby.

If you find yourself in that group, you probably want to know when and how you can know the sex of the baby that you're carrying around for nine months.

Keep reading as we explore when you can find out, and take you through the different methods and tests used to identify the sex of your baby during pregnancy. We've also included a couple of traditional (non-scientific!) ways that can be fun to try out at home.

Related: The Most Popular Gender-Predicting Old Wives' Tales of All Time


When Do You Know the Sex of Your Baby?

There are a couple of different ways your healthcare team can tell you the sex of your baby. The first is through a blood test performed on the pregnant person, which can be done as early as the first trimester. The second way to determine your baby’s sex is by viewing the baby with an ultrasound at the mid-way point of the pregnancy.

You may have also heard of at-home gender tests. These can also be done on your own at home just a month or two after you find out you are pregnant, but experts feel these at-home tests may be less accurate than tests offered by your healthcare provider.

Methods for Determining Baby’s Sex in the Womb 

As mentioned above, you can find out the sex of your baby by getting a blood test or ultrasound from your healthcare provider. The method used will be based on how far along you are in your pregnancy.

Blood Test (10+ Weeks Pregnant) 

Your healthcare provider can order a blood test as early as 10-12 weeks of pregnancy to determine the baby's sex. Dr. Anar Yukhayev, OB-GYN at Long Island Jewish Medical Center, Northwell Health tells Family Education a bit more about this method.

"One (way to find out) is with a blood test in the office looking at cell-free fetal DNA with a NIPT test and that I do around 10 weeks of pregnancy. This is 99.9% accurate," says Yukhayev.

The non-invasive prenatal testing (NIPT) is a medical test that is meant to screen for Down syndrome (trisomy 21)  and other chromosomal abnormalities or genetic disorders. 

Because the test works by isolating fetal DNA in the bloodstream of the pregnant person, this test not only checks for chromosomal problems, but it also tells you the sex of your baby. 

NIPT analyzes your baby’s DNA. If the test detects a Y chromosome – it would indicate that your baby is male. And if this test only detects X chromosomes, that would mean your baby is a female. 

How Accurate is a Blood Test to Determine Sex? 

Because it is a medical test, not everyone is able to get this test performed. This test may also be less accurate if you are pregnant with more than one baby, but the science in this area is improving rapidly. 

Not all healthcare providers have this test available, so if you are interested, you should talk to your OB/GYN or midwife about whether this blood test is an option for you.

Ultrasound (14+ Weeks Pregnant)

The most common way people find out if they are having a boy or girl is through a pregnancy ultrasound. Pregnancy ultrasound has been standard practice for many years. Because this method directly views your baby, it requires your baby to grow a bit and develop more. This means that an ultrasound to determine the sex of your baby is most accurate in the second trimester. 

Using sound waves through an ultrasound machine, sonographers view the baby and take pictures of the different body parts. This is called an anatomy scan and is typically performed about halfway through the pregnancy. This is an important test for checking on your baby’s development. 

How Accurate is an Ultrasound to Determine Sex? 

The sonographer can accurately identify the sex of the baby anywhere from 97% of the time up to 99% of the time. Sometimes an ultrasound technician cannot detect the baby's sex with an ultrasound because the baby is too small or might not be in the best position to view the baby's genitals or sex organs. 

Sometimes the baby is moving too much, and won’t hold still for good views. There may also be something obstructing the view. Whatever the case, if the results aren't there to plan your gender reveal party just yet, the sonographer may ask you to go back for another ultrasound scan a bit later for a clearer sex determination. 

In addition to the cell-free fetal DNA test and ultrasound imaging, which are both common in pregnancy, there are a couple of other tests that could give you information about your baby’s sex. These tests, called chorionic villus sampling (CVS) or amniocentesis, take samples of either placental tissue or amniotic fluid which can be used to evaluate your baby’s chromosomes. 

These tests are more invasive and carry some risk, so they are typically only offered when your pregnancy is high risk, or if your healthcare provider is worried about the health of your baby.

IVF Sex Selection 

Some people know that they are having a boy or girl before they are even pregnant. For some couples who are going through in vitro fertilization (IVF) to conceive a pregnancy, determining the sex of the baby before implanting the pregnancy is important. 

This is commonly done by families that carry genetic disorders which only affect boys or girls. These families can undergo genetic testing on the embryo, and then choose the sex of the embryo that is least likely to be affected by the illness. This can increase their chances of giving birth to a healthy child.

Can I Use an At-Home Test to Find Out Baby’s Sex? 

While many pregnant women go to their healthcare provider when they want to know the sex of their baby, others turn to at-home tests to see what that form of gender prediction has to say. 

These at-home tests work by taking a small blood sample using a lancet to collect blood from the finger of the pregnant person, which is then put in a collecting device. The collecting device is sent out to a lab for analysis to see if you're having a boy or girl. Within a week, sometimes sooner, you receive the results of the sex of your baby.

But, Yukhayev warns pregnant women about using this test if they want the most accurate gender test.

"The at-home gender reveal kits are tricky because they claim to use the same technology as the NIPT to look for gender, but they are run in unaccredited labs," says Yukhayev. There is also a chance for contamination as the sample is obtained by the pregnant person instead of by a trained lab technician or nurse.

He says there is only a small amount of blood drawn for the test, which can lead to an inconclusive result. These results could also be inaccurate if there is contamination with DNA from someone else in your home. While contamination could occur in a formal lab setting as well, it is likely less common due to strict procedure controls.

"The study that they cite as showing 99.9% accuracy is an industry-sponsored trial and in all of their patients, blood was drawn as opposed to a simple finger prick which is actually advertised with their product," Yukhayev points out.

Yukhayev says the clinic-based blood test and ultrasound scans are the most accurate ways to find out if you're having a baby boy or baby girl.

If you are considering an at-home test, talk to your healthcare provider to get their opinion about whether you should use it to determine your baby's sex.

Old Wives’ Tales for Determining Baby’s Sex

Some pregnant women look for gender-predicting old wives' tales or other non-scientific ways of determining if their baby is a boy or a girl. While these are fun to try out, none of them have been shown to accurately predict the sex of the baby.

Heart Rate 

Many people have heard from a friend or a family member that the heart rate of their baby can indicate if they are expecting a boy or a girl. According to Johns Hopkins, there is no evidence to support this idea. The heart rate may follow a predictable trend of climbing until about 9 weeks gestation, then dropping back down a bit, but this does not vary based on whether your baby is a boy or a girl.

Morning Sickness 

morning sickness
Image Source: Getty Images

Another common myth is that morning sickness is worse in pregnancies where the baby is a girl. There may be a little bit of truth to this, but some people experience no morning sickness with a baby girl, or debilitating morning sickness with a baby boy. Unfortunately, guessing the baby’s sex based on the degree of morning sickness is just that - a guess.

Urine Baking Soda Test 

There is a home test some people do the baking soda test. This test involves combining a pregnant person’s urine with baking soda to see if it fizzes. If the urine fizzes, then a woman is preparing for a baby boy. According to the old wives' tale, a baby girl is on the way if the urine does not fizz.

The Ring Test

Another old wives' tale is the ring test. To perform this test, you tie a ring on a piece of string and dangle it over your belly. If it swings in a circular motion, the test predicts that you are having a girl. If it swings side to side, the test predicts that you are having a boy. 

You can do this fun little test during your first trimester or at any other point during your pregnancy. It may even be fun to do it once you've had the NIPT test or your anomaly scan to see if they match up with the predicted sex of your little one.

Carrying High vs. Carrying Low 

One other old wives’ tale is based on how you're carrying your baby. If you're carrying high, rumor has it you're having a girl while carrying low could indicate a boy.

In the end, we all know the only foolproof way to find out your baby's sex is at birth. But, if you just can't wait and feel like you need to know, you can ask your OB-GYN about the blood test or an ultrasound scan. These are the most accurate ways to determine the sex of a baby.

Once your healthcare provider tells you if you're expecting a boy or girl, you can start planning, picking baby names, and shopping for your little one's arrival. It may seem like a long time until you meet, but it will be here before you know it.

Sources +

Ammar, A., Husnain, M.A.Z., Arshad, M., Mirza, T.M.,Arshad, Z., Arshad, T, Arshad, D. & Amjad, M. (2021). Accuracy of ultrasound for determination of fetal gender. PJMHS 15(6).

Costa, J.M. & Ernault, P. (2002). Automated assay for fetal DNA analysis in maternal serum. Clinical Chemistry 48(4).

Ralph, K. & Polson, D. (2012) A woman's decision to know the sex of her child prior to birth. BMUS 20(3).

Shipp, T.D., Shipp, D.Z., Bromley, B., Sheahan, R., Cohen, A. Lieberman, E. & Benacerraf, B. (2004). What factors are associated with parent’s desire to know the sex of their unborn child? Birth Issues In Perinatal Care 31(4).

Villela, D., Che, H., Van Ghelue, M.,Dehaspe, L., Brison, N., Can Den Bogaert, K., Devriendt, K., Lewi, L. Bavindir, B. & Vermeesch, J.R. (2019). Fetal sex determination in twin pregnancies using non-invasive prenatal testing. NPI Genomic Medicine 4(15).


Kristina Cappetta

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