You can’t exactly see it, but your body (and baby) are accomplishing amazing things during pregnancy. From what’s happening with your uterus and placenta to what baby can sense, we’ve got the scoop on the mind-blowing things going on inside you.

  1. Your Uterus Is Growing to 14 Times Its Original Size Yep, it will stretch from the size of a pear to the size of a watermelon (and go back down again), says Sherry A. Ross, MD, an ob-gyn and women’s health expert at Providence Saint John’s Health Center in Santa Monica, California. The uterus holds between four and six pounds of liquid (that’s almost two pint glasses full!), like mucus and amniotic fluid to cushion baby in utero.

  2. Your Heart Is Pumping a Whopping 40 to 50 Percent More Blood Than It Did Pre-Pregnancy It’s also beating 10 to 20 more times per minute than it did before. This is to fuel the umbilical cord and placenta—and to prep for the main event: baby’s birth. It totally makes sense now why you get tired so much faster than you did in your prebump life, doesn’t it?

  3. Baby Can Hear You By 18 weeks gestation, the ears will have fully developed, and baby can very likely hear your voice, the vacuum and the dog barking. When you sing to baby, they’re actually listening and may recognize the songs after birth as being extra-soothing.

  4. If It’s a Boy, He Could Be Having Erections Even before birth, baby’s tiny reproductive system has started prepping. Between 20 weeks and 23 weeks, a boy has already started making sperm. At that time, a girl’s ovaries and uterus are also fully formed, with a lifetime supply of eggs.

  5. The Placenta Is Doing the Work of Four Organs Sometimes called the “tree of life,” this organ (that you just recently grew!) is extremely elaborate and helps baby eliminate waste, filters away bad things, supplies all their blood and feeds them. Talk about the ultimate multitasker!

  6. Baby Tastes Their Meals Believe it or not, by week 20 of pregnancy, baby has developed taste buds and is already learning to prefer the foods you eat. Some experts even believe you can shape baby’s palate by eating a wide variety of (healthy!) foods during your pregnancy. You’re probably already paying attention to what you’re eating, but here’s extra motivation to order a side of broccoli instead of French fries! Related Video

  7. Your Breasts Are Full-Fledged Milk Producers Nope, this isn’t just a postpregnancy thing. Hormones trigger milk production pretty much right after you become pregnant, and by 20 weeks, baby’s first milk (a thin yellow liquid called colostrum) is already in there, Ross says. You may notice leaking during the third trimester—nothing that nursing pads can’t fix.

  8. Baby Is Making Poop As you near the midpoint of pregnancy, baby starts producing meconium, the black, tarry substance that they’ll expel soon after birth to fill their first dirty diaper.

  9. Baby Can See Light Around week 30, the irises are completely formed, meaning baby can see and might even react to light. And surprisingly, it’s not always completely dark in your womb. If you lie in the direct sunshine, you might notice baby move to try to shield their eyes.

  10. Baby Is Rehearsing for Their Crying Debut Anticipating what it will be like to hear that first cry? Baby is too. Ultrasound photos have shown babies making crying and other facial expressions in the womb. This doesn’t mean baby’s sad, though. Crying is actually an important skill for baby to master, since it will be the primary way of communicating with you during those first exciting weeks. About the expert: Sherry A. Ross, MD, is an ob-gyn and women’s health expert at Providence Saint John’s Health Center in Santa Monica, California, and author of she-ology and she-ology, the she-quel: let’s continue the conversation. Please note: The Bump and the materials and information it contains are not intended to, and do not constitute, medical or other health advice or diagnosis and should not be used as such. You should always consult with a qualified physician or health professional about your specific circumstances. This post contains affiliate links, some of which may be sponsored by paying vendors. Plus, More from The Bump: Pregnancy Symptoms You Will Actually Like 10 Surprising Pregnancy Symptoms No One Warned You About How to Deal with Body Aches During Pregnancy

1. Your Uterus Is Growing to 14 Times Its Original Size

2. Your Heart Is Pumping a Whopping 40 to 50 Percent More Blood Than It Did Pre-Pregnancy

3. Baby Can Hear You

4. If It’s a Boy, He Could Be Having Erections

5. The Placenta Is Doing the Work of Four Organs

6. Baby Tastes Their Meals

7. Your Breasts Are Full-Fledged Milk Producers

8. Baby Is Making Poop

9. Baby Can See Light

10. Baby Is Rehearsing for Their Crying Debut