Can Ultrasounds Be Wrong About the Sex of Your Baby?

Pregnancy ultrasound
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Can an ultrasound be wrong? Do you worry about ultrasound gender mistakes? Ultrasound in mid-pregnancy is frequently used to tell the sex of the baby by having the ultrasonographer (sonographer) scan for the baby's genitalia. At this point they will announce, "It's a boy!" or "It's a girl!" Though for some families, this statement turns out to be wrong.

Reasons for Ultrasound to Be Wrong About Sex

Can ultrasound be wrong about baby's sex? Yes. Does it happen frequently? It's hard to track because there isn't really a registry of answers. How does it happen? Here are a few examples.

Too Early

The best time to be able to determine the sex of your baby is between 18 to 20 weeks. An ultrasound done before this relies not necessarily on external genitalia but on the direction of the genital tubercle, depending on how early the ultrasound is performed. An ultrasound done after this point risks the part you are looking at being crowded out as the baby grows.


Not all ultrasound machines are created equally. In fact, some ultrasound machines are simply very old and may not give the best views.

Baby Doesn't Cooperate

Let's face it, not all babies are exhibitionists. I've heard many a mom say, that baby simply wouldn't show off for the sonographer. If that happens, the determination of girl or boy may be made on poor images from a positioning point of view. It is also harder to tell the sex of the baby if the baby is in a breech position, has their legs crossed, hands near their genitals, etc.


We've all heard the old joke about the baby girl being called a boy because she had the umbilical cord between her legs, but there is truth to the topic in that an inexperienced sonographer can make a mistake. An experienced sonographer can too, but they are less frequent.

Maternal Weight

It's a simple fact that if you are heavier, ultrasound image quality is less clear. This can cause difficulty in scanning. Combined with other factors and it may be really difficult to tell the sex of your baby. You may need to rely on other tests.

What You Can Do

There are plenty of reasons why it may happen, some of which you have control over. Don't push the envelope and try to schedule the ultrasound appointment early just because you're anxious, as you risk getting information that isn't right. Ask about the equipment and the experience of the ultrasonographer.

As for baby's cooperation, good luck on that one. Some ultrasonographers recommend you drink a caffeine-free carbonated sugar-filled drink before the ultrasound to get your baby active.

When Mistakes Do Happen

You can imagine the shock, disappointment and even grief that parents feel when their dream baby boy or girl isn't born, but their baby is the other sex. It takes many people a while to recover from this shock.

One small study showed that when women experienced the wrong sex prediction it lead to more than just a distrust of ultrasound; some also experienced marital strife and domestic violence. The earlier the mistake is discovered the easier it can be to shake it off say some.

It's OK to feel horrible about this, despite what others may tell you. This is often referred to as gender disappointment. One mom referred to it as a mental miscarriage. She said it wasn't that she didn't love the baby who was here, but it simply wasn't the baby she's been dreaming about and getting to know for the last nine months. It took her a few weeks to reconcile the new baby with her dream baby.

Other families are able to laugh it off and move on. There is no one way to deal with it. The key is simply being true to yourself.

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