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Pregnancy: When can you find out the sex of your baby?

You may be in for some really big news soon—finding out the sex of your baby. 

Maybe you want to wait and be surprised. Or maybe you really, really want to know—ASAP! If the suspense and excitement is just too much to bear, read on and learn when you can find out if you're having a boy or girl. 

What determines a boy or girl?

Let's talk for a moment about how your baby's sex was determined in the first place. That happened not so long ago in your life, when egg met sperm during conception. To understand this a little better, it's helpful to review what you may have learned in high school biology.

A human's genetic material contains 46 chromosomes—23 from the mom's egg and 23 from the dad's sperm. The mom and dad each contribute one sex chromosome. A woman's egg always contributes an X sex chromosome. A man's sperm can contain either an X or Y sex chromosome. The combination of the two is what determines a girl (XX) or a boy (XY).  

When can you find out?

If you want to know the sex of your baby, you may be able to find out between the 18th and 20th week of your pregnancy, according to the March of Dimes. 

Around this time, you may have a mid-pregnancy ultrasound exam to check on baby's development. During this test, your provider may be able to tell you the baby's sex. (If you don't want to know, say so before the scan!)

How does an ultrasound work?

An ultrasound uses soundwaves to produce a black-and-white image of your baby inside your womb. Ultrasound scans are very accurate. But they can't always show the baby's sex. Depending on your baby's position, his or her genitals might not be in full view. This might make it difficult for your provider to tell you if you're having a boy or girl with any certainty. 

What about other ways?

A couple of other tests that can also tell the sex of your baby are chorionic villus sampling (CVS) and noninvasive prenatal testing (NIPT). CVS is an invasive test in which cell samples are gathered from the placenta. NIPT is a blood test. Both CVS and NIPT are diagnostic exams done primarily to diagnose certain genetic conditions, like Down syndrome. So you likely won't have them unless your provider recommends you do. 

More pregnancy news

Too excited to keep your pregnancy to yourself? For ideas on going public with your baby news, try these creative ideas for announcing your pregnancy

Sources: American Pregnancy Association; March of Dimes; Office on Women's Health

Reviewed 2/28/2021

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