When a woman finds out that she’s expecting, she’s bound to have a lot of questions. One of the first things that a new mom is most curious about is… just what exactly is going on in there? How big is that baby? And how big will that baby actually GET?
A lot of books and websites offer helpful comparisons to fruit and vegetables. Some of them we’re pretty familiar with. But some of them aren’t exactly very helpful. Just how big is a dragonfruit, anyway? Haven’t seen any of those in the produce department at the grocery store recently!
By the end of their pregnancy, most women feel like they’re carrying around a beach ball… or a basketball… or a bowling ball. Well, that’s because they kind of are! Babies born at 40 weeks measure, on average, just over 20 inches (51 centimeters) long. The normal range for baby length is between 18 inches (46 centimeters) to 22 inches (56 centimeters.) The average weight of a baby who’s made it to 40 weeks is a little over 7.5 pounds (3.5 kilograms.) Anywhere between 5.5 pounds and 10 pounds is considered normal.
Newborns grow at a rapid pace after they enter the world. Although they may lose as much as half a pound in the first week or so after birth, babies usually gain it back by their two-week visit to the pediatrician. And they’ll continue to pack on about a half a pound a week during their first month, in addition to growing about two inches longer!
Of course, that big, healthy baby started out teeny-tiny! Read on to see just how small babies are at 4 weeks… and how big they get during pregnancy!
17 Week 4 - A Speck Of Glitter
At four weeks, you probably don’t even know your pregnant yet. But that embryo is already growing, and is just about as big (uh… I mean small!) as a tiny speck of glitter. In other words, that’s about 0.014 to 0.04 inches long. As for weight? We’re talking 0.04 ounces. Tiny!
The embryo consists of two layers – the epiblast and the hypoblast; this is from where all of her organs and body parts will develop. Your baby’s organs will start developing from now until 10 weeks, and some will even begin functioning.
The early placenta is also made up of two layers at this point. Cells are growing into the lining of your uterus, creating spaces for your blood to flow so that when fully-developed, the placenta will be able to carry nutrients and oxygen to the baby.
And, at only 4 weeks, the amniotic sac and amniotic fluid are also present. The embryo also has a yolk sac, which is responsible for making the baby’s red blood cells and carrying nutrients to her until the placenta is ready to take over.
16 Week 6 - A Mini Chocolate Chip
By now, at six weeks pregnant, you might be starting to deal with annoying and uncomfortable pregnancy symptoms. On the bright side, your baby is growing like crazy! The folds of tissue in the prominent bump on top (the baby’s head) are developing into the baby’s jaw, cheeks, and chin. Little dimples are forming on either side of the baby’s head, which will eventually become ear canals. Little itty-bitty dots on the face will eventually be eyes and a nose in a couple weeks. This week, the baby’s kidney, liver, lungs, and heart are also taking shape! The baby’s heart beat is probably somewhere around 110 beats a minute.
All of this is going on in something the size of a miniature chocolate chip!
As baby grows, the doctor will measure her from crown to rump (top of the head to her butt) because her legs will be curled up and it will be hard to get an accurate measurement of the full length of her body. At six weeks, the baby’s crown-to-rump measurement is anywhere from one-fifth to one quarter of an inch!
15 Week 8 - An App Icon
During your 8th week of pregnancy, your baby weight about .04 ounces and measures a little over half an inch. Pull out your iPhone – she’s probably about the size of an app icon! And she probably grows about a millimeter every day! Her fingers and toes are now only a little webbed, and her tail is now gone. (Ever wonder why it’s called a tail bone?) Her taste buds are also starting to form.
Speaking of taste buds, let’s talk about your pregnancy symptoms. By now, you could be dealing with all kinds of weird pregnancy side effects, like weird cravings, a heightened sense of smell, morning sickness, sore boobs, fatigue, and crazy pregnancy dreams.
Around this time, you’ll probably be heading to your first prenatal appointment, if you haven’t done so already. You’ll get an exam and a pap smear to check for infections, and will have to give a urine sample to monitor your glucose and protein levels. It’s also likely that you’ll have a blood draw at this appointment to check your hormone levels and red and white blood cells. You’ll also be screened for different STDs and immunities to common diseases.
14 Week 10: A Tater Tot
At ten weeks along, your baby is anywhere from 1.20 inches to 2 inches in length and weighs about 0.14 ounces. She’s still so tiny that she’s got lots of room to float around in your amniotic fluid. But, even though your little tater tot is small, she’s growing a little bit more proportionately; her head doesn’t seem as big when compared to the rest of her. She also has wrists and ankle joints and fully-formed fingers and toes, now!
In addition to her appendages, several more of her organs are forming and starting to function. Her intestines are still actually a part of the umbilical cord, but will soon start to move into her abdomen. Her lung tissue is continuing to develop, her thyroid is now operating, her pancreas is making digestive enzymes, and her gallbladder is already secreting bile – all signs that her digestive system is already working!
13 Week 11 - A Golf Ball
Even though you can’t tell your baby’s gender yet, it’s around this time that she’ll start developing ovaries – if she’s a girl. By week 11, she definitely resembles a tiny little human. She has tiny hands and feet, her ears are almost in their final shape, and there are open nasal passages on the end of her nose. Fingernail and toenail beds begin developing sometime this week, and soon, her nails will begin growing!
Currently about the size of a golf ball, your baby’s body is lengthening and straightening out in there. She can now start stretching, rolling, and tumbling around in there – although you can’t feel her yet. (Just wait! It’s coming!)
If you were experiencing morning sickness, hopefully by now it’s easing up and you’re getting your appetite back. You need to eat well to nourish you – and that growing baby! Just remember that you don’t really have to eat for two. About 300 extra calories a day is all you need!
12 Week 12 - A Wine Cork
You still have several weeks to go before you can enjoy a glass of wine again, but by now, at 12 weeks along, your baby is the size of a wine cork! It's around this time that your baby finishes developing new body parts and now just has to focus on growing and evolving! Her digestive system starts contracting, which is what it will need to do to push food through it. Her bone marrow is making white blood cells, which is what will eventually help her fight infection. And it’s hard to believe, but the pituitary gland at the base of her brain is already producing hormones!
At this month’s checkup, you might get to hear your baby’s heartbeat. It kind of sounds like a washing machine, but it’s still one of the most beautiful sounds you’ll ever hear!
Know what else? The end of week 12 marks the end of the first trimester! Congratulations, mama!
11 Week 14 - A Rubik's Cube
Welcome to week 14! This is the second trimester. Hopefully you’re feeling more healthy and energetic. A lot of women tend to feel better during the second trimester, so enjoy it while it lasts! Use this time to start preparing for baby: start planning the nursery, registering for gifts, looking into childbirth classes and thinking about what kind of delivery you’d like to have. Also, if your doctor gives you the go-ahead, consider getting into a prenatal yoga class or picking up some gentle exercise.
By now, all of your baby’s organs, nerves, and muscles are starting to do their jobs. If you could see her little face right now, you might see her smiling, wincing, and grimacing – her facial muscles are developing and flexing. Your baby is about 4 to 4 ½ inches long and now weighs around 1 ¾ of an ounce, making her about the size of an old school Rubik’s cube; remember those things?
10 Week 15 - A Baseball
By week 15, your uterus is now starting to grow up and out of your pelvis, so you might finally have a noticeable bump going on. You might actually look pregnant, instead of just a little thicker in the middle! But even though you might finally be showing, your baby is still only about 5 inches long; she probably weighs around two ounces. She’s about the size of a baseball!
And even though you’ve still got a way to go, your body is doing what it needs to do to get you ready for labor and delivery. You might be feeling Braxton-Hicks contractions, which help warm up your uterus for the real contractions that will eventually deliver your baby. These contractions don’t hurt like the real thing, and just feel like your abdominal area is tightening and then releasing.
Your milk glands might be kicking into production, which means you might see what looks like droplets of water sitting on the ends of your nipples. You might even have tiny wet spots on your bra or shirt. If you have to, you can start using breast pads (or even trim up a pantyliner) inside your bra to guard against leaks.
9 Week 16 - A Cell Phone
At week 16, your baby weighs somewhere around 3 to 4 ounces and is about 4 to 5 inches in length. Back in week 8 of your pregnancy, your baby was only the size of an app icon on your iPhone screen. Now your baby is as big as the whole cell phone! Can you hear me now?
Actually, yes, your baby can hear in there already. Your baby can hear you when you talk on the phone and can hear you when you're singing along to the radio in the car. In fact, some studies have found that babies that hear songs in the womb can recognize them after they're born!
Although her eyes are still shut, her eyes are working and can move back and forth. She can even tell if it’s light or dark. She’s also working on growing her eyebrows and eyelashes. Her, skin, however, is still pretty see-through at this point.
8 Week 19 - A Pint Of Ice Cream
How are you doing, mama? Feeling pretty big? Well, be prepared: your belly is going to start growing even more in the next few several weeks. During all this growth, you may notice that your lower abdomen seems to ache, and you might even notice a quick, stabbing pain on one or both sides. This is probably round ligament pain – the ligaments that support your uterus are stretching to hold that growing belly! If you get uncomfortable, sit down and put your feet up. Maybe even dig into a pint of your favorite ice cream?
That’s actually about how big your baby is right about now, at week 19 – about the size of a pint of ice cream. She probably weighs in somewhere around 8 ½ ounces and measures around 6 inches long. Her arms and legs are proportionate to the rest of her body now.
And congratulations are in order – you’re almost halfway there!
7 Week 20 - A Top Knot
You’re halfway there! Your baby weighs about 10 ½ ounces now. She’s also probably about 6 ½ inches from head to rump, and looking more and more human every day! Her lungs are still developing and she might be swallowing amniotic fluid – a practice that helps her digestive system function properly.
Your baby will also be making herself known by now, and you should be feeling it. She’s in there twisting and turning, curling up and stretching out, but thankfully, she still has plenty of room – for now, anyway!
Her skin is developing different layers. And her hair and fingernails are continuing to grow. Speaking of hair and nails, you might be enjoying one of the benefits of pregnancy – thick, luxurious hair and strong nails! Put all that hair up in a top knot; your bun in the oven is about as big as a bun on top of your head!
6 Week 24 - A Big Burrito
At week 24, your baby is about 11 to 11 ½ inches long and probably weighs about 1 1/3 pounds. She’s about the size of a big burrito. She’s gaining weight steadily and packing on about six ounces a week. Most of the weight that she’s been putting on comes from growing organs, muscles, bones, and baby fat. Until that fat gets deposited under the baby’s skin, her skin is still transparent – if you could see in there, you could see straight through her skin to all of those organs, bones, and blood vessels. Don’t worry! She’ll plump up soon! At this point, her face is almost fully formed, complete with eyelashes, eyebrows and hair. (But there’s no pigment in the hair yet!)
Heads up! Most women have a glucose screening test between now and 28 weeks. This test checks for gestational diabetes. Untreated diabetes can increase your risk of having a difficult delivery or needing a C-section because it causes your baby to grow too large. It also raises the risk of complications for your baby right after birth. While a positive result on your glucose screening doesn’t mean that you have gestational diabetes, it does mean that you’ll need to take another test, the glucose tolerance test, to find out for sure.
5 Week 28 - A Baseball Cap
Welcome to the third trimester! Moms-to-be who are 28 weeks pregnant or further along usually end up having trouble sleeping. For one thing, it’s hard to get comfortable with that big belly. Another problem causing you to lose sleep might also be your little one. You go to bed to get some shut-eye, but she’s up and moving around in there! Even though you might feel like getting up and doing something (because you’re likely nesting at this point) try to rest and relax. Baby time is getting closer!
Your baby can blink her eyes, and she may be able to see the light that filters in through your skin. She’s developing billions (with a B!) of neurons in her brain and is finally plumping up and adding more body fat to her frame. By this week, she weighs a little over two pounds and is probably 14 to 15 inches from the top of her head to her heels. She’s as big as a baseball cap!
4 Week 30 - A Garden Gnome
Your baby is getting bigger every day. By week 30, she is about the size of a garden gnome! She weighs in around 3 pounds. She’ll continue to pack on about half a pound a week for the next seven weeks! Her brain is also growing like crazy. Up until now, her brain tissue has been smooth, but now it’s starting to wrinkle up; those wrinkles actually allow for even more brain tissue to grow. By now, your baby’s bone marrow has completely taken over the job of making red blood cells.
Now that your little one has finally packed on some fat cells, she’s been able to regulate her body temperature a little more on her own. That means that the soft, fuzzy hair called lanugo that’s been covering her skin, is starting to disappear. (Although she may still have a few leftover strands of fuzz and fur on her back and shoulders when she’s born.)
3 Week 33 - A Cute Little Chihuahua
It’s week 33 and your baby may be anywhere from 16 to 17 inches in length. She probably weighs a little over four pounds and is still gaining weight. With her size, she’s taking up most of the space in your uterus now. You probably have more baby in there than amniotic fluid, which means that she’s starting to run out of room. That means it probably feels like she’s doing more kicking and punching than rolling around like a little puppy in there. Speaking of puppies, she’s about the size of a chihuahua!
But forget the puppy comparison for now; your baby is now acting more and more like a baby! Her eyes close when she goes to sleep and open when she’s awake. She’s doing a better job of differentiating between day and night, so hopefully she remembers the difference after she’s born and you’re trying to catch up on some much needed sleep!
2 Week 37 - Zach Morris' Giant Cell Phone
You’re almost at the finish line! At week 37, your baby is now considered full term! Of course, you want to keep that bun in the oven as long as you possibly can. She probably weighs around 6 pounds and is close to 20 inches long. Your doctor can’t really tell how big she’ll be at birth, but you if you want an idea of how big she is right now, picture Zach Morris from Saved by the Bell with his giant cell phone. That’s a big phone! And a big baby!
And your baby is going to continue to grow, every single day. At this point, some babies are still in a breech position, but most babies should be in a head-down position, getting ready to… head out! It might feel like your baby is less active than she was a few weeks ago, but it just seems that way because she’s so cramped in there!
1 Week 39 'til You Deliver - A Beach Ball
We know, mama. You probably feel like you’re carrying a beach ball in there. That’s because you kind of are. That baby is about as big as a beach ball! That baby is probably 20 inches long and weighing around 7 pounds by now.
At this point, any fear you had of childbirth has probably been replaced by impatience and just wanting to get this show on the road! At 39 weeks pregnant, you might not have any signs of labor yet. On the other hand, some women may start to show a dilated and/or effaced cervix and even experience some contractions… although it might still be days or weeks before they go into labor. The average first-time mom-to-be goes into labor naturally at 41 weeks. Second-timers tend to deliver at 40 weeks.
No matter what the calendar says, call your doctor if you think your water breaks. It might not be like the movies. No huge gush, but a slow trickle of liquid. If you have a watery discharge, it probably means the amniotic sac has ruptured. That means… labor is near! Not everyone’s water breaks, though, or you might not be able to tell. If that’s the case, give your doctor a call when you start feeling regular contractions that come closer and closer together.