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
Backaches
Backaches
Bleeding gums
Bleeding gums
Fast-growing nails
Fast-growing nails

Tips for You This Week

Put your feet up

Finding it harder to tie your shoes than usual? Swollen feet and ankles may be to blame. So go ahead, put your feet up!

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-kick-back sessions throughout the day.

Write some reminders

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, jotting down notes for yourself, and outsourcing some of your regular tasks to your partner, friends and family.

Take a walk

Is your plumbing clogged? Then start walking for exercise. Both during pregnancy and in those early 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 (or 30 minutes spread out in smaller increments) 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.

Break the big sibling news

You’ve already made the announcement to your family and friends, to much fanfare — but telling your toddler that you’re expecting is likely to be met with … crickets.

It’s not surprising: Your toddler’s whole world will be changing, and that can be upsetting (not to mention a little scary). To help ease the transition, read your child books about pregnancy like Before You Were Born: The Inside Story or pull up some old pictures of when you were pregnant with her.

Once you can feel the baby move, put her hand on your belly so she can feel the tiny flutters, or ask her to weigh in on potential baby names.

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. It can lead to trouble sleeping and even a new habit of snoring.

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. Nasal strips can also help.

Rethink hair removal

Shaving used to be a cinch — but now, you might have trouble seeing below your belly. While a shower can soften your hair and skin, making it easier to remove, always shave after you've finished, since a slip-up could be serious.

If your skin isn't too sensitive, you might want to try waxing and sugaring (ask your doctor if it's okay first), which is a long-term solution to unwanted hair.

As for bleaches, lasers and hair removal creams, the jury is still out on whether they're safe to use during pregnancy, so consider shelving them until after you give birth.

Go for a swim

Want a reprieve from your achy muscles and joints? Try taking a dip in the pool. In the water, you weigh just a tenth of what you do on land, allowing you to feel lighter and more limber. Bonus: Many women say that the cool water helps ease pregnancy stomach woes. 

Just tread carefully when you’re on deck — the pool deck, that is. The slippery surface, along with your growing belly, can throw off your balance.

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.

  1. What to Expect When You’re Expecting, 5th edition, Heidi Murkoff.
  2. WhatToExpect.com, How to Remove Hair During Pregnancy Safely, March 2021.
  3. WhatToExpect.com, "Pregnancy Brain" or Forgetfulness During Pregnancy, August 2022.
  4. WhatToExpect.com, Stuffy Nose and Nosebleeds During Pregnancy, June 2023.
  5. WhatToExpect.com, Constipation During Pregnancy, October 2022.
  6. WhatToExpect.com, Allergies During Pregnancy, August 2022.
  7. National Institutes of Health, National Library of Medicine, Fetal Development, July 2021.
  8. National Institutes of Health, National Library of Medicine, Cell Reports, Development of the Fetal Bone Marrow Niche and Regulation of HSC Quiescence and Homing Ability by Emerging Osteolineage Cells, October 2014.
  9. Current Biology, Early Influences on the Development of Food Preferences, May 2013.
  10. American Academy of Dermatology, Stretch Marks: Why They Appear and How to Get Rid of Them, November 2023.
  11. National Institutes of Health, National Library of Medicine, Stretch Marks, August 2023.
  12. American College of Obstetricians and Gynecologists, Weight Gain During Pregnancy, January 2013, reaffirmed 2023.
  13. American College of Obstetricians and Gynecologists, Nutrition During Pregnancy, June 2023.
  14. National Institutes of Health, National Library of Medicine, Eating Right During Pregnancy, November 2022.
  15. National Institutes of Health, National Library of Medicine, Canadian Family Physician, Safety of Skin Care Products During Pregnancy, June 2011.
  16. American College of Obstetricians and Gynecologists, Skin Conditions During Pregnancy, July 2022.
  17. National Institutes of Health, Office of Dietary Supplements, Iron, June 2023.
  18. Clinics in Dermatology, Striae Gravidarum, March 2006.
  19. National Institutes of Health, National Library of Medicine, American Journal of Obstetrics and Gynecology, Risk Factors for the Development of Striae Gravidarum, January 2007.
  20. WhatToExpect.com, Stretch Marks During and After Pregnancy, April 2021.
  21. WhatToExpect.com, How Many Weeks, Months and Trimesters in a Pregnancy?, May 2022.
  22. WhatToExpect.com, When Babies Develop Taste Buds and Start Tasting Food, May 2021.
  23. WhatToExpect.com, Anxiety During Pregnancy, April 2021.
  24. WhatToExpect.com, Edema (Swelling of the Ankles and Feet) During Pregnancy, October 2022.
  25. WhatToExpect.com, Walking During Pregnancy, November 2021.
  26. WhatToExpect.com, How to Help Your Child Prepare for Your New Baby, February 2019.
  27. WhatToExpect.com, The Best Pregnancy Workouts and Exercises You Can Do While Expecting, July 2021.
  28. WhatToExpect.com, Clumsiness During Pregnancy, September 2022.
  29. WhatToExpect.com, When Can You Feel Your Baby Move and Kick?, February 2023.
  30. WhatToExpect.com, Has Your Appetite Increased During Pregnancy?, December 2022.
  31. WhatToExpect.com, What to Do About Bloating During Pregnancy, February 2021.
  32. WhatToExpect.com, Back Pain During Pregnancy, January 2022.
  33. WhatToExpect.com, Sore and Bleeding Gums During Pregnancy, January 2022.
  34. WhatToExpect.com, Nail Changes During Pregnancy, November 2022.

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