You’ve heard about the morning sickness and weird cravings, but did you know that pregnant people also have to deal with something called “lightning crotch?” It’s a sudden, sharp pelvic pain. Lightning crotch doesn’t mean labor has started, and it usually isn’t serious. It’s thought to be caused by the fetus’s position within the parent’s body.

Only 4 percent of babies are born on their due date. And pregnancy can cause long-term changes to someone’s body: from shrinking the amount of gray matter in the brain, to causing the pelvis to separate.

In our latest episode of The List Show, we’re covering some surprising—and occasionally horrifying—facts about pregnancy.

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This article was originally published on www.mentalfloss.com as 20 Surprising (and Horrifying) Facts About Pregnancy.