Hilary Duff is opening up about experiencing a common yet not-talked-about-enough pregnancy symptom: lightning crotch.

Appearing on The Ellen DeGeneres Show, Duff told fill-in host Brooke Baldwin how her current pregnancy has been great—except for the painful condition.

"I didn't have it with the other kids," the actress explained. "So, I texted my midwife the other day, and was like, 'What's up with the stabbing pains in my vagina?'"

Duff continued, "It feels awful, like you're being struck by lightning."

The Younger actress said she was surprised by her midwife's relaxed reply.

"She just wrote back, and she was like, 'Oh, lightning crotch'—like it was no big thing. I was like, 'This is quite traumatic,'" Duff laughed.

"Like, it'll just strike and all of a sudden you're doubled over. And then it's gone," she added.

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Duff is far from alone in experiencing lightning crotch.

"Yes, this is what we actually call it, because as you may already know, that's exactly what it feels like—a sudden, sharp pain in your vagina," writes Diana Spalding, MSN CNM in The Motherly Guide to Becoming Mama.

"It usually happens toward the end of pregnancy in response to the baby moving or because of the increasing pressure being applied to your cervix by the baby's head. So, it is a good sign that things are moving in the right direction.

Unfortunately, there is not much you can do about it when it strikes, though you can try lying down on your left side to decrease some of the pressure."

Staying active throughout your pregnancy can help keep the condition at bay. If you get this pain over five times in an hour and you are earlier than 37 weeks pregnant, call your doctor or midwife to make sure it's not preterm labor, recommends Spalding.

We feel for Duff—lightning crotch might sound funny, but it's no joke!

Thankfully, she won't have to deal with the condition much longer.

Duff says she only has a few weeks left in her pregnancy.

The actor is already mom to an 8-year-old son, Luca, from a previous marriage. She and husband Matthew Koma also share a 2-year-old daughter, Banks. And in a few weeks, they'll add a third little one to the mix!

Duff says she and Koma don't know the gender of their baby.

"We don't know the gender of the baby," she insisted. "We found out with Banks what we were having, and I found out with Luca. And we were just like, 'You know what? This has been a crazy year, let's do something even more crazy and not find out what kind of baby we're having.'"

We love that approach! Best of luck to the growing family—and we hope Duff has a pain-free end to this pregnancy!