There are many things I wish someone had told me before I gave birth 429, and at the top of the list is that I would shake like I was naked in a snowstorm for an hour afterward. You’d think head-to-toe quaking would be something to mention to a newbie. When I experienced this after delivering my first child, I thought something was terribly wrong.

Turns out, even if it was unpleasant, all that shaking was normal.

Not everyone has intense shivering during labor or after delivering, but whether you have a vaginal birth or a C-section—or this is your first baby or your last—studies have indicated that you have between a 44% and 55% chance of it happening to you. Those are some pretty big stats.

The exact cause of postpartum shaking, trembling or teeth-chattering isn’t fully understood. But several factors could be in play.

Giving birth is hard, physical work

Hormones regulate everything—how our hearts beat, our metabolism, temperature control, growth, cell recovery, how much we pee, how we handle stress, our moods, sleep patterns… and when and how we give birth. During labor, subtle shifts in hormone levels create an avalanche of physical and emotional responses. The oxytocin that causes uterine contractions can also produce muscle contractions in your legs, back, arms and feet. Add to that some mega doses of stress hormones like adrenaline, cortisol and epinephrine, plus the rapidly shifting hormones that transition you through labor and delivery, and your body’s massive physical reactions may cause you to shake.

What causes postpartum shaking?

Your body temperature can fluctuate postpartum and make you shake.

With all the energy it takes to push out your baby, your body temperature can rise a degree or two during labor, making you feel hot. But shivering usually occurs as a regulatory response to cold, causing muscle contractions to increase body heat as a protective mechanism.

You can shiver whether the room is cold or perfectly warm. Anesthesia can lessen your body’s natural ability to regulate its own temperature. Having an epidural opens up blood vessels to your skin, increasing blood flow that results in heat loss, causing a small decrease in your core (central) body temperature.

Knowing postpartum shaking is a possibility gives you one less thing to worry about if it does happen. Generally, shivering can’t hurt you, so try not to fight it. It is possible that straining to reduce the shaking that comes after a C-section could actually lead to some problems at the incision site.

There are safe ways to help or prevent postpartum shaking

If you do shake after you deliver your baby, usually you will be given warm blankets to help your muscles relax and reduce the shivering. And some research has indicated that the shaking can be lessened by warming IV fluids before they are administered. Scientists still aren’t sure how this works, but many studies suggest that temperature sensing receptors in your spinal canal are responsible.

It’s good to remember that postpartum shaking might not happen to you

So many factors contribute to postpartum shaking. And just because you experienced shivering in the past births, doesn’t mean that you will shiver in the future.

Lastly, shaking is usually normal but if you are worried, never hesitate to ask your provider—especially if it happens in the days following your birth. If you feel chills like you do when you have the flu in the days following your delivery, you may have a fever, and that could indicate an infection and should notify your provider right away.

A version of this story was originally published on Feb. 18, 2021. It has been updated.