When my mom was pregnant with my oldest brother, she was certain he was a girl. This was in the early 1980s before a sonogram could tell you the sex of your baby.

But my mom says she just knew he was a girl. She was so sure, she and my dad named him Isabelle and called him that while he was still in the womb.

Imagine their surprise when he popped out and was definitely not an Isabelle.

Stuff like this happened all the time before the 1980s when it became pretty common to get a sonogram that could tell you the sex of your baby.

But these days, most people aren't usually surprised by the sex of their newborn. Sonograms can tell you what sex your baby will be as early as 18 weeks into pregnancy. There are even sonograms that can give you a 3D image of your baby while it's growing inside you if you're really desperate to get a peak. (Although personally, I think the 3D sonograms make all babies look like squished aliens and they scare me, but that's something I can work out in therapy).

Some people still choose to be surprised by the sex of their baby.

But most people already know when they go into labor if they are having a boy or a girl.

There isn't a lot of data on the subject of how many parents decide to find out the sex of their baby.

A study from 2001 says about 58% of couples know before having a baby if it will be a girl or a boy.

Couples who decide not to know the sex of their baby may be surprised at birth, but couples who do find out rarely are in for a surprise.

Ultrasound techs are usually pretty good at determining sex by looking at the baby. But apparently...not always.

That was the case for a couple in North Carolina.

Nancy Ray was pregnant with their third baby.

Ray is a wedding photographer and podcaster from North Carolina.

You can find her absolutely beautiful Instagram here.

Nancy and her husband Will already had two girls, so they decided not to be surprised by their third.

They hadn't found out the gender for her last two births, but according to Nancy, her husband needed some time to mentally prepare in case he was about to be the dad to yet another girl.

So they decided to find out the sex.

And it turned out her husband needed that time because the sonogram showed Nancy was having another girl!

The couple was excited, of course, but a little disappointed.

The whole family, including their daughters Millie and Lyndon, had been hoping for a little brother.

They decided to hire a birth photographer to document the birth.

Photographer Lauren Jolly showed up just in time to get some photos of Nancy in labor.

Jolly is a birth and lifestyle photographer from Winston-Salem, North Carolina.

She's shot over 25 births.

But this one was about to be one of the more surprising she'd ever shot.

Nobody knew it, but something completely unexpected was about to happen.

According to Jolly, Nancy only pushed for a few minutes before delivering her baby.

via: Lauren Jolly Photography

Then Nancy pulled the new baby into her arms and said, "Our daughter is here."

But that's when she noticed something...a little extra.

The sonogram was wrong.

It wasn't a girl at all, it was a boy!

They had their son, after all!

Jolly managed to capture a photo of the exact moment Nancy realized she wasn't holding her daughter, she was holding her son.

via: Lauren Jolly Photography

And it's hilarious.

The expression on her face really says it all.

via: Lauren Jolly Photography

Excitement, joy, and absolute shock.

In the photo, you can even see her husband lifting the baby's leg to double check.

via: Lauren Jolly Photography

According to Jolly, Nancy said, "Wait is this a boy baby?!"

Her husband fell to his knees after realizing he had a son after all.

via: Lauren Jolly Photography

And they had to think of a new name, fast! The name they had planned, Rosie, probably wasn't going to work on this baby.

They ended up naming the baby Beaufort.

via: Lauren Jolly Photography

Jolly said everyone was in complete shock and she's mostly glad she had the sound mind to keep shooting photos.

The birth was attended by midwives, and although the midwives noticed the gender right away, they decided not to tell Nancy and let her figure it out when they put the baby in her arms.

Which was the perfect decision, because otherwise, she would not have gotten her hilarious photo.

Jolly says this was definitely the biggest surprise she's ever had in her career as a birth photographer.

It was an extra special moment for her, because Jolly wasn't just Nancy's photographer, the two have been friends since high school.

The photo has gone completely viral.

Everyone seems to love this story.

But this had me wondering: how often does this happen?

It turns out the answer is almost never. It's really rare for ultrasound predictions to be wrong. Sometimes a baby is positioned in a way that makes it hard to tell if it's a boy or a girl, but in that case, the ultrasound tech will usually tell the parents that their prediction is not 100% certain.

Predicting the sex of a baby through ultrasound is not super technical.

They basically just do what anyone else would do. Look for a penis. If they see one: congrats, it's a boy!

If they can't see a penis, it's a girl.

Pretty simple.

And also pretty accurate.

Ultrasound gender predictions are only wrong about 2% of the time.

But there is always a possibility the penis could be hiding.

In Nancy's case, they only had one ultrasound since she was delivering with midwives at a birthing center, not an OBGYN.

They only got to look at the baby once before he was born.

And apparently, he was feeling particularly shy that day because from what they could see, he looked like a girl.

Nancy and her husband now have a beautiful family of five.

Beaufort was born in December 2018.

Welcome to the world, Beaufort!

You sure know how to make a dramatic entrance.