Most people know the basics of pregnancy, but do you know some of the more in-depth and amazing things that happen inside your body when you're pregnant? We've picked 10 of the most impressive things that happen during pregnancy to share with you. There really is so much more to it than you realize!

1. Conception

As sperm meets egg and cells begin to divide you are in the earliest stages of being pregnant. If your pregnancy was achieved the old-fashioned way, sperm swam through your uterus and into your fallopian tubes to find a single tiny egg (unless you're expecting fraternal multiples). That two microscopic cells can find each other inside your body is really amazing. If you conceived with scientific help, that's equally as amazing for different reasons. Either way, conception is a mind-blowing and truly random kind of miracle.

2. Implantation

Now that your baby-to-be is a rapidly dividing ball of cells, it's traveling through your fallopian tubes and into your uterus. Your uterus has been building up a lining of blood for the last few weeks on the off chance that a little ball might make its way down and implant. If you're pregnant, that means that it did. The odds seem stacked against a little speck of cells just happening to settle in and attach itself to the inside of your body in just the right place. Again—amazing and miraculous.

3. Humans have Yolks, Too!

After your baby implants, but before the placenta has formed, how does he get the nourishment to grow? It turns out that even humans have yolks. The yolk sac forms and provides nutrition and early blood circulation. By about 12 weeks of development the placenta will begin to work so the yolk sac will be absorbed and eventually become part of your baby's gut.

4. You Grow a New Organ

There are so many incredible things about the placenta—like, it's the only organ that you grow and then get rid of when you're done with it. While your baby is growing, the placenta acts as a liver, lungs, and kidneys for the baby, and as an endocrine system for both of you. Since the placenta is made of about 50% maternal cells and 50% fetal cells, it's a joint effort that keeps both of you running until the birth.

5. Your Body Creates an Antibacterial Barrier

The opening from your vagina into your uterus is called the cervix—and it never fully closes. When you're pregnant it is obviously not good for bacteria to get into your uterus, but how do you do that when there isn't a natural closing? To help protect the baby and placenta, your body creates a seal called the mucus plug. The mucus plug contains antimicrobial agents to deter passage of harmful germs, keeping your baby safe.

6. Your Breasts are No Longer Just for Show

After about two months of pregnancy you'll start to notice that your breasts are getting fuller or larger. When you're pregnant, part of your body's preparation for baby is getting your breasts ready for nursing. You'll likely notice that your areolas become darker—which is great because newborns have really bad vision; the contrast makes them easier for baby to find. Many expecting moms also find that colostrum begins to leak a bit, resulting in a strange (but totally normal) crust forming on nipples or inside of bras.

7. Your Pelvis "Relaxes"

OK, there's so much going on down there right now it's impossible to imagine your pelvis is doing anything other than freaking out, but, a hormone named Relaxin is already working on loosening things up. In order for your baby to have enough wiggle room to pass through your pelvis your joints need to stretch out a bit. Relaxin helps pelvic ligaments stretch enough to let baby through more easily when the time comes.

8. Your Uterus is Practicing for the Big Day

While most people assume that contractions only happen during labor, your uterus has been practicing all along. Braxton Hicks contractions can start as early as six weeks into pregnancy—though it's unlikely you'll feel any of them until the second or third trimester. Practice contractions may help your uterine tone, but are unlikely to have any effect on your cervix. If they become painful or are accompanied by bleeding, call your doctor, otherwise, try to relax—they usually only last for a minute.

9. Your Cervix Might Already Be Dilating

As you reach the end of your pregnancy you know that labor will happen soon (but not soon enough, right?). As you've read in every baby book and seen in movies, the big moment everyone is waiting for is for you to be dilated to ten centimeters (almost four inches). What most people never mention is that dilation can happen well before labor. It isn't unusual for women to stay two or three centimeters dilated during the last month of pregnancy. The relatively large size of your baby's head and the fact that your cervix hasn't begun to thin out, or efface, is what keeps everything in place.

10. You Go Into Labor

Women have been having babies forever, but we're still not sure what exactly causes real labor contractions to begin. It's thought that it might be something in the baby's brain that triggers a chain reaction of hormones that start real uterine contractions—but nobody is absolutely certain how it works. All we know is that at the end of it, your baby is born, and all of the amazing things your body has gone through during the last nine months are what got her here.