When is the Boy or Girl Gender Reveal Ultrasound?

You wait five minutes. You turn over that white stick. You peer down and see the sign of your dreams—that little pink plus. 

The stork is finally on its way! Now, a million more questions race through your head: What do I eat? How soon will I feel a kick? Will my baby be a boy or a girl—and when will I find out? 

Enter the gender reveal ultrasound—a procedure during the second trimester of your pregnancy, typically around weeks 18 to 21. While parents are usually most excited about learning the gender, this ultrasound also provides more information than that. If you’re curious to learn more, take a look at our guide for everything you need to know about the gender reveal ultrasound (and ultrasounds in general). 

Plus, now you can see if your Chinese Gender Predictor and Gender Quiz predictions are right!

What is an ultrasound? 

The word ultrasound may sound a little intense, but this imaging technology has been safely used for decades to:

• Determine baby gender
• Predict the baby’s due date
• Monitor the health of mothers and their babies during pregnancy

How do ultrasounds work? This technology uses non-ionizing radiation, a.k.a. sound waves. Have no fear, the non-ionizing radiation in ultrasounds does not carry the same risks as ionized radiation (i.e., the type of radiation used in X-rays). This means your little guy or girl will stay safe throughout the procedure.

To create an image of your baby and the inside of your uterus, ultrasound machines project sound waves that bounce off your internal organs and structures. The resulting echoes form a sonogram (i.e., an ultrasound scan) of the interior area. You’ve likely seen sonograms before when friends or family members have announced that they’re expecting. They’re often grainy black and white images that depict the familiar profile of a growing fetus. 

While we may not be able to see much more than a baby profile during an ultrasound, your doctor can actually learn a lot about the health and development of your child. 

Why Ultrasounds are Important

Pregnancy comes with a loooooong to-do list, from preparing the nursery to practicing your one-handed diaper change on that baby doll you bought. During all this pregnancy prep, you might wonder—do I really need to add an ultrasound to my calendar?

The answer is a resounding yes. 

Ultrasounds aren’t just crystal balls for predicting your baby’s gender. They also reduce maternal and fetal health risks, track your baby’s growth, and help you plan for the little bundle on the way.

Depending on when you have your ultrasound, your doctor will be able to detect: 

• Fetal heartbeat 
• Fetal health defects or abnormalities
• Fetal positioning (head-up or head-down)
• Gender
• Potential pregnancy risks (such as low amniotic fluids or preeclampsia)
• Ectopic pregnancy (a condition that occurs when the fertilized egg doesn’t attach to the uterus)

When do you have an ultrasound? 

We get it—once that pink plus sign appears, the desire to learn your baby’s gender tops your wish list. But to determine your baby’s gender with ultrasound, you’ll have to wait just a little bit longer. 

This doesn’t mean you won’t have an ultrasound right away. While the American College of Obstetricians and Gynecology recommends having at least one ultrasound during pregnancy, most pregnant women end up having two—one during the first trimester and one during the second trimester. The exact number of ultrasounds you’ll receive (and when you’ll receive them) depends on your personal health needs. 

For the newly pregnant, if you’re wondering what weeks do you get ultrasounds during pregnancy? Let’s take a closer look:

Early Pregnancy Ultrasound (6 to 8 weeks) 

At the earliest, moms-to-be can receive a prenatal ultrasound around 6 weeks. This initial 6-week ultrasound isn’t necessary for most women, but it’s useful for catching any high-risk pregnancy conditions. Doctors will recommend an early-stage ultrasound in the case of:

• Miscarriage history
• Genetic birth defect history
• Ectopic pregnancy history 
• Abdominal pain
• Vaginal bleeding

Since your baby barely forms a belly bump at this stage (at 6 weeks, the fetus is only the size of a pomegranate seed!), this ultrasound is typically transvaginal. This means a medical professional will insert an ultrasound wand through the vaginal canal, so they can get up close and personal with your little baby pomegranate. 

This early pregnancy ultrasound: 

• Detects the baby’s heartbeat
• Determines if you’re carrying more than one baby
• Estimates your due date

Dating Ultrasound (11 to 14 Weeks) 

If you didn’t receive an early pregnancy ultrasound, a dating ultrasound is usually recommended between 11 to 14 weeks. This 12-week ultrasound check-up allows practitioners to:

• Predict your due date
• Determine the number of babies in your womb
• Detect ectopic pregnancy 
• Monitor the fetal heartbeat 

Around 11 weeks, your baby will be about the size of a prune. This growth from seed to prune has caused your uterus to expand outward, closer to the wall of your abdomen during this gestational age. This means you can receive a transabdominal ultrasound, where a medical professional glides the ultrasound wand over your abdomen to create the sonogram image. 

Gender Reveal Ultrasound (18 to 21 Weeks) 

Finally, gender identification! After 18 to 21 weeks of referring to your baby as an “it,” you get to learn whether to expect a little he or a little she—all thanks to the second–trimester ultrasound. In fact, around week 18, an ultrasound determines a baby’s gender with 99% accuracy.

Compared to first trimester scans, this ultrasound provides a more detailed and thorough examination of your baby. Beyond learning the baby’s sex, your doctor will also check for the following during a second–trimester ultrasound:

• Heart defects
• Organ health
• Placenta positioning
• Amniotic fluid levels
• Chromosomal abnormalities
• Baby gender (it’s so exciting, it’s worth mentioning again)

Can you read a gender reveal sonogram? (H2)

Peering at your gender reveal sonogram, you might feel a bit confused. How could anyone see what gender your growing baby is through these grainy, black-and-white scans?

Medical professionals have a few solid pointers for reading your gender reveal sonogram. Let’s break down the top markers for determining a boy or girl ultrasound image. 

Boy Sonogram Images 

With male fetuses, sonographers can make a few identifying mistakes. The earlier the ultrasound (regardless of whether 3D ultrasound or 4D ultrasound), the more likely a professional will mischaracterize a boy as a girl, which is why using an ultrasound to determine gender is most accurate beginning at 18 weeks. When examining the image, your sonographer will look for these male-leaning signs:

• Sagittal sign (male) – When looking at an ultrasound, you typically see the side profile (or sagittal plane) of the baby. From this view, sonographers track the baby’s spine down to the tailbone to find the caudal notch—a little nub at the base of the spine. If this little notch is pointed upwards by more than 30 degrees, then the fetus is male. If the angle is less than 30 degrees, predictions are less accurate.
• Urine flow – Between weeks 18 and 20, ultrasounds can also detect a baby’s urine flow inside the womb. If the urine is flowing upwards, then the fetus is likely a boy (cause…well, you know).
• Male genitalia appearance – In the case of baby boys, it’s more about what you can see rather than what you can’t see. Identifying any male genitalia at all (the penis, scrotum, testicles, you name it) is the easiest way to determine a male baby.

Girl Sonogram Images 

With less visible genitalia, girl fetuses are a little more difficult to identify. By week 18, though, a sonographer can usually tell if pink will be your nursery room’s color. Medical professionals will check for these female-leaning signs:

• Sagittal sign (female) – Like boy babies, girl babies can be identified via the caudal notch. If that little nub is pointed downwards by around 10 degrees, then you’re likely carrying a baby girl. 
• “Hamburger” sign – The hamburger sign means there’s a visible clitoris or labia folds in the sonogram image. Inside the womb, these sexual growths often look like a hamburger, which explains the name of this sign.
• Lack of visible male genitalia – Occasionally, a female fetus’ genitalia isn’t clear on the ultrasound. In these cases, you can rule out a boy baby if there are no signs of male genitalia around 18 weeks or later.

Learn Your Baby’s Gender As Early As 6 Weeks with SneakPeak 

After waiting months to become pregnant, waiting another 18 weeks to learn your baby’s gender can feel like an entire lifetime. If you can’t wait any longer, we don’t blame you. In fact, that’s exactly why our team created a faster solution—the SneakPeak Gender Blood Test.

The SneakPeek test is the #1 OBGYN-recommended at-home gender test. At just 6 weeks into pregnancy, this easy-to-use test can reveal your baby’s gender with over 99% clinical accuracy¹. That’s weeks earlier than a gender reveal ultrasound (and more accurate, too!)

Simply use our at-home kit to collect a DNA sample in the comfort and privacy of your own home. Before you know it, you’ll learn whether you’re going to be the parent of a handsome boy or a sweet girl. So forget waiting—join the over 1 million moms who learned their baby’s gender sooner – with SneakPeek Test.

Editorial Policy

At SneakPeek, our commitment is to provide accurate, up-to-date, and reliable information to empower our readers. Our content is thoroughly researched, reviewed by medical experts, and fact-checked to ensure its credibility. We prioritize the well-being and education of our readers, and our editorial policy adheres to the highest standards of integrity and accuracy in all our articles.

This post has been reviewed for accuracy by:

Haley Milot

Haley Milot, a highly skilled laboratory professional, currently serves as the Associate Director of Lab Operations at Gateway Genomics, the parent company of SneakPeek. Her extensive experience in laboratory management, spanning over seven years with Gateway Genomics, showcases her expertise in quality assurance, quality control, and the development of laboratory procedures. Haley's background includes pivotal roles in DNA extraction and purification, real-time qPCR, and specimen accessioning, underscoring her comprehensive understanding of laboratory operations and diagnostics. Her adeptness in managing complex laboratory functions and her deep knowledge of medical diagnostics make her a vital contributor to SneakPeek's innovative approach to prenatal testing.

Sources:

1. American College of Obstetricians and Gynecologists. Ultrasound Exams. https://www.acog.org/womens-health/faqs/ultrasound-exams
2. Beth Israel Deaconess Medical Center. Ultrasounds During Pregnancy: How Many and How Often? https://www.bidmc.org/about-bidmc/wellness-insights/pregnancy/2018/09/ultrasounds-during-pregnancy-how-many-and-how-often
3. Healthline. Pregnancy Ultrasound. https://www.healthline.com/health/pregnancy/ultrasound
4. Parents Magazine. Pregnancy Ultrasounds Week by Week. https://www.parents.com/pregnancy/stages/ultrasound/ultrasound-a-trimester-by-trimester-guide/
5. US Food and Drug Administration. Ultrasound Imaging. https://www.fda.gov/radiation-emitting-products/medical-imaging/ultrasound-imaging
6. Very Well Family. How to Tell a Baby’s Gender on the Ultrasound. https://www.verywellfamily.com/ultrasound-photos-of-girls-and-boys-in-pregnancy-2758367
7. What to Expect. ​​Ultrasound During Pregnancy. https://www.whattoexpect.com/pregnancy/pregnancy-health/prenatal-testing-ultrasound/
8. Healthline. 6 Weeks Pregnant: Symptoms, Tips, and More. https://www.healthline.com/health/pregnancy/pregnancy-symptoms-week-6#:~:text=At%20week%206%2C%20your%20baby,arms%2C%20legs%2C%20and%20ears. 
9. Medical News Today. Your pregnancy at 10 weeks. https://www.medicalnewstoday.com/articles/299161#baby-development