Motherhood is rough.

I'm not talking about emotions here. I'm talking physically rough. I'm talking just-got-back-from-the-doctor-with-a-minor-concussion rough. Seriously. My preschooler gave me a concussion.

In what will forever be known in our family as the day mom officially became a wimp, my 4-year-old daughter slammed her head into the back of mine. She was fine; I screamed in pain. A week of headaches later, I went to the doctor (despite my husband's mockery) and was told I likely have a concussion.

It’s not my first injury of motherhood. From scratches to bruises to an almost broken nose, I find myself constantly putting my hands up to protect my face when I see either of my daughters barreling toward me.

My 4-year-old and I have talked about personal space bubbles many times. She thinks it is hilarious to pop mine.

The 1-year-old isn’t much better. You wouldn’t think such a little thing could get so much momentum behind her enormous noggin. But I’ve learned to get out of the way when I see that melon coming at me.

I expected the physical trauma of motherhood to be over when you leave the delivery room. Oh no. Then you’ve got a child who will spend the next 10 years pile-driving you in the living room and throwing her head into your nose.

I would have expected this kind of roughhousing from boys. Boys come home from the hospital with a small tag clamped to their umbilical cord reading, "Warning: This baby will one day jump off the roof of the house with a grocery bag as a parachute."

But I have daughters. Aren't girls supposed to have tea parties? I didn't expect my sweet little daughter to be doing kamikaze dives off the back of the couch, or into my skull.

Then again, I was never the play-by-herself-quietly type of child, either. I was stitched up multiple times — once for using the countertops as mini-parallel bars to propel my chin directly into the floor, and once for stepping on a hanger while dancing around with a pillowcase on my head. I was what you might call a moron.

So maybe this is payback for all the grief I caused my own mother. Or perhaps it's all part of the immutable law of motherhood: A child at rest never stays at rest, and a child in motion will stay in motion until he hits someone square in the face.

Erin Stewart is a regular blogger for Deseret News. From stretch marks to the latest news for moms, Stewart discusses it all while her 4-year-old daughter crams Mr. Potato Head pieces in her little sister's nose.