When my husband and I decided to have a baby, we knew that we were entering into the unknown but we still thought we had some idea of what to expect; turns out we were wrong about a lot of things.

Here are nine things that surprised me about being a new parent.

1. That nothing will really prepare you for being a parent.

Before I gave birth, I took parenting classes and read parenting books. But the truth is that nothing can really prepare you for your baby. Each baby is different, and you'll get to know your baby and cater to his or her needs.

I still panic sometimes when my daughter cries, but at least by now I recognize what the different cries mean. Also, babies reach the big milestones in their own time, so don't panic if your baby isn't rolling over or crawling when the baby books say they should.

2. That newborns sleep constantly.

Newborns can sleep up to 18 hours a day. When I brought my baby home from the hospital, I kept waiting for her to wake up and play. Turns out that she mostly just slept (and ate and cried and pooped). Feeding her was a challenge because she would constantly fall asleep, and we would spend hours on end tickling her feet, calling her name, and even rubbing water on her to try to get her to wake up and eat.

3. That sleep deprivation is utterly debilitating.

Just because a newborn is sleeping doesn't mean parents will get any rest. The single hardest thing about being a new parent is the sleep deprivation. When you bring home a newborn, there's a good chance you'll never sleep for more than two or three hours at a time — at least in the very beginning. Even though newborns sleep for almost 18 hours a day, they're up every two to three hours to eat — and eating can easily take an hour, meaning that sometimes you'll only be able to sleep for one hour at a time before it's time to start the next feeding. Try to sleep when the baby sleeps.

4. That babies are extremely expensive.

I knew that a baby would be expensive, but I didn't factor in how much the basics really rack up. Consumer Reports estimates that parents will spend at least $2,500 on diapers by the time their child is potty-trained. I signed up for Amazon Mom ($79/year), which offers discounts on diapers and baby essentials as well as free shipping, and it's already paid for itself. Diapers.com also had great deals. Formula can also be really pricey, but it's a necessity if you're planning to formula feed your baby. And then there are the essentials, like cribs and strollers, that can add up to thousands of dollars. If you choose to buy them used, make sure they are up to current safety standards.

But those costs are minor compared to the big picture: It costs an estimated $241,080 for a middle-income couple to raise a child to 18 years of age, according to a 2013 report from the U.S. Department of Agriculture.

5. That breastfeeding can be incredibly difficult.

Before I had a baby, I thought they just grabbed on and started sucking. Turns out it's a lot more complicated than that. There can be difficulty with latching, swallowing, milk supply, clogged milk ducts, and more. And when a baby can't eat, it's terrifying because it can mean a life or death issue. I learned that there's a whole industry devoted to breastfeeding: There are lactation consultants, all sorts of products, and even whole stores devoted entirely to breastfeeding.

6. That babies make a ton of laundry.

It's amazing how such tiny beings can make such an insane mess. Between explosive poops, spraying pee, and spit-up and throw up, be prepared to go through tons of diapers, clothes, burp cloths, bibs, and blankets. And I mean TONS. If you can afford it, hire someone to do the laundry for you — you'll be happy you did.

7. That new parents are late for everything.

Don't even bother scheduling appointments when you're caring for a newborn. Your baby has other plans for you. It's hard enough to get yourself and the baby dressed, but there's always an element of the unknown. Just as you're walking out the door, your baby may start wailing inconsolably or take such a big poop that the clean-up will require a full bath.

8. That everything can be forgiven when your baby smiles.

Don't underestimate the power of cute. You can forgive the messy diapers, the lack of sleep, and everything else when your baby smiles at you. And the first time my baby laughed? That was one of the best moments of my life.

9. That it changes your life in every way possible.

After you become a parent, there's no going back. There's no more late night bar-hopping, no more spontaneous travel, and no more last-minute plans — at least at the beginning. You'll always be responsible for this tiny, helpless being, and that's a terrifying but amazing feeling.