At 21 weeks pregnant, your baby has more control over limb movements, which explains why you might be feeling more kicking and stretching going on in there.

From the outside, your little one may be leaving his mark in the form of stretch marks — pink, red, purple, reddish-brown or dark brown streaks that can appear as your belly expands.

Your Baby at Week 21

At a Glance

He's got the moves
He's got the moves
Your baby's arms and legs are in proportion this week and his movements are now much more coordinated. Also, notice a jump in baby's length this week? Up until now, we've been measuring from crown to rump, but now we start to measure from crown to heel, which explains why he suddenly "grew" so much.
More blood cells
More blood cells
Your baby-to-be's liver and spleen have been working hard producing blood cells, but now the bone marrow is developed enough to help too.
Baby's drinking
Baby's drinking
While the placenta is still #1 when it comes to nourishment, now your baby takes in small amounts of amniotic fluid, too.

21 weeks pregnant is how many months?

If you're 21 weeks pregnant, you're in month 5 of your pregnancy. Only 4 months left to go! Still have questions? Here's some more information on how weeks, months and trimesters are broken down in pregnancy.

How big is my baby at 21 weeks?

How big is your baby? Switching from crown-to-rump to crown-to-heel length, he's 10½ inches long and weighs 11 to 12½ ounces, about the size of a large banana.

Your developing baby still has a great deal of room in your womb — though like anyone who lives in one space for a long time, this tenant will soon begin to feel cramped.

Baby's moving and sleeping

Until those uterine walls start closing in, however, there's plenty of space for twisting, turning and even an occasional somersault — so that's what you were feeling last night!

With all that belly dancing going on, it's hard to believe your baby is getting any shut-eye at all. But believe it or not, your fetus sleeps as much as a newborn. Now if only you could get some sleep yourself!

Baby's taste buds develop

Speaking of milestones, whatever you eat this week, there's a good chance your baby will taste it, too. That's because when you're 21 weeks pregnant, your baby swallows a bit of amniotic fluid each day — not only for nutrition and hydration, but also to practice swallowing and digesting, skills he'll need as soon as he arrives in your arms.

And keep this in mind: The taste of the amniotic fluid differs from day to day depending on what you've eaten — spicy enchilada one day, sweet banana the next. That smorgasbord of flavors won't be lost on your baby since your little one has very developed taste buds already.

In fact, researchers have noted that babies who were exposed to certain tastes in utero via the amniotic fluid were more eager to eat foods with those same tastes after birth. Want your peanut to eat his broccoli later? Eat yours now!

Baby's getting coordinated

Your little action figure is able to choreograph Matrix-like moves at 21 weeks pregnant. Arms and legs are finally in proportion, neurons are now connected between the brain and muscles, and cartilage throughout the body is turning to bone.

All these upgrades combine to give your baby more control over limb movements, which explains all that kicking, stretching and bodysurfing, or rather bellysurfing, you may have started feeling.

Your Body at Week 21

21 weeks pregnant woman

Stretch marks

At 21 weeks pregnant, your baby might be starting to leave his mark — in the form of stretch marks, that is — all over your stomach, butt, thighs, hips and breasts.

These pink, red, purple, reddish-brown or dark brown streaks appear as your body expands and your tummy and breasts just keep on growing: The supporting tissue under your skin gets torn as the skin stretches.

Estimates vary, but at least 1 in 2 women get stretch marks, though you're a likely candidate if your mom had them during pregnancy.

Rapid weight gain can also predispose you to getting stretch marks — another good reason to add your pounds slowly and steadily, at an average of about a pound a week these days. 

Depending on your complexion and the genes you inherited, these lines first show up as red, pink or brown streaks, and with time, will eventually fade.

There's no proven way to prevent stretch marks from zigzagging their way across your body (though there's no harm in applying moisturizers like cocoa butter; if nothing else, it will prevent the dryness and itching associated with pregnancy-stretched skin). After delivery, they usually fade to a less noticeable shade.

Relieving anxiety

Now that you're starting to look pregnant — and not just like you ate a particularly large lunch — and those kicks can no longer be mistaken for gas, the reality of pregnancy is probably beginning to sink in.

And with it, you may find, a few ambivalent or anxious feelings you're even ambivalent about admitting: Me, a mom? There must be some mistake! Don't worry — and hang on.

At some point in pregnancy, and usually once that pregnancy becomes a very visible reality, just about every expectant parent begins to feel anxiety and fear — almost as if you're on a runaway train and there's enormous changes coming round the bend.

And not only is it completely normal to feel anxious, it's especially healthy to acknowledge it. Talk your feelings over with your friends who've had babies — they’ll reassure you that they experienced the same kind of thoughts. Most important, discuss your fears with your partner, if you have one, who's probably just as in need of a good heart-to-heart.

Learn more about anxiety during and after pregnancy.

Pregnancy Symptoms Week 21

Fetal movement
Fetal movement
Increased appetite
Increased appetite
Bloating and gas
Bloating and gas
Bleeding gums
Bleeding gums
Fast-growing nails
Fast-growing nails

Tips for You This Week

Unstuff your nose

Seasonal allergies may not be to blame for all that nasal congestion you've been experiencing. Alas, starting in the second trimester, a stuffy nose is a common pregnancy symptom — one that tends to stick around until delivery.

To clear your nasal passages, use your thumb to close one nostril, while gently blowing out the other. Then, repeat on the other side. If you're really stuffed up, ask your doctor if there's a safe OTC decongestant or antihistamine you can use.

Elevate your feet

Finding it harder to tie your shoes than usual? Swollen feet and ankles may be to blame. Because your body has about 50 percent more blood and fluid than it did pre-baby, your extremities are more prone to swelling. So be sure to clock in a few sit-and-elevate sessions throughout the day.

Slow and steady wins the race

Chances are your practitioner advised you on your target weight gain at your first prenatal appointment — and that it was calculated based on a number of factors, including what your pre-pregnancy weight and BMI were.

Your practitioner probably also talks to you at every visit about where you are on that upward curve — and where you should aim to be.

If you've been instructed to gain the standard 25-to-35-pound total in your pregnancy, by this week you're likely to have gained anywhere from 10 to 16 of those pounds.

If you raced past that number weeks ago, or are gaining faster than your practitioner recommended, you'll want to slow down. And if you’re not gaining enough, you'll want to speed things up. Ask your doctor or midwife for tips.

Walk for 30 minutes a day

Is your plumbing clogged? Then start walking for exercise. Both during pregnancy and in those first postpartum weeks, physical activity like a brisk walk is one of the best ways to stimulate your bowels and fight constipation.

Just a half-hour walk a day can do the trick, especially if you drink plenty of water and favor fiber-rich foods. Just remember to take some trail mix when you hit the trail. And even if you’re not doing it to relieve constipation or other pregnancy symptoms, walking is a great way to get the exercise you need when you’re pregnant.

Avoid lasers

Your legs, armpits, bikini line and upper lip may be hairier than usual due to all those raging hormones. But think twice before you turn to lasers, electrolysis, depilatories and bleaching.

No reliable studies have been done to determine for sure whether these popular hair-removal and lightening treatments are harmful or not, but it's probably best to skip them until after you give birth.

Take heart, though — you may pluck or shave to your heart's content. Even waxing is fine if your skin's not too sensitive. That's not making you feel better? Chin up — you're more than halfway to the finish line!

Clear your calendar

It's not a lack of sleep that's causing you to forget where you put your keys (though that certainly doesn't help). Brain fog is a common pregnancy symptom, and causes forgetfulness and trouble concentrating.

Since so-called “pregnancy brain” could well be here to stay for the remainder of your pregnancy, now's the time to start making to-do lists, leaving notes for yourself in obvious places and outsourcing some of your regular tasks to your partner or non-pregnant friends and family.

Limit empty calories

Emphasis on “empty.” You still want to consume enough nutrients to keep your baby fed and growing. After all, the idea isn't to lose weight — losing weight is always a bad idea when you're pregnant — it’s to eat a healthy diet and keep your weight gain slow and steady.

Easy, nutritious strategies, like substituting fresh fruit for dried, baked potatoes or yams for French fries, and grilled white-meat chicken with no skin for fried dark meat with skin, can make a big difference.

Other calories that can go? The ones you'll find in sugary treats.

From the What to Expect editorial team and Heidi Murkoff, author of What to Expect When You're Expecting. What to Expect follows strict reporting guidelines and uses only credible sources, such as peer-reviewed studies, academic research institutions and highly respected health organizations. Learn how we keep our content accurate and up-to-date by reading our medical review and editorial policy.

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