Twin Pregnancy Week 21: Symptoms, Baby Size, Body Changes & more

21 Weeks Pregnant With Twins or Multiples

Medically Reviewed By
Dr. Sabiha Anjum (Gynecologist/Obstetrician)
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Now that you’re 21 weeks pregnant with twins, you can’t really wait to meet your babies. You must be thinking about the due date already, but your little ones are still developing and they need their due time so that they can grow properly. At 21 weeks, your little ones will continue to grow and you should continue to expect changes in your body too. These changes could exhaust you, but they are essential for accommodating the little ones growing inside you. Read this article to learn how your babies are developing at week 21, the changes you should expect in your body, and more.

The Growth of the Babies at 21 Weeks

With the halfway point way behind you now, the babies also begin to realise that they need to catch up with their growth and keep themselves ready to survive in the outside world. Most of the progress is focused on ensuring all those systems are functioning appropriately.

Food is the key to survival and this also becomes one of the top priorities for the growth of the babies this week. The digestive system, having appropriately developed, initiates its processing and begins attempts at digesting the food. This is precisely where the black coloured meconium is formed inside the baby and stays there until it is flushed out in the baby’s first poop. The initial digestion processes within the child also generate enzymes and acids to support the function correctly.

The acts of sucking and swallowing also progress rapidly, as your babies tend to take in a lot more amniotic fluid and may even prefer sucking on their thumbs more than usual. All of these are the methods which assure the body that it is fit to survive outside.

With all these inputs focused on food and digestion ensuring that it can be synthesised, the excretory systems within the babies also begin to function at a higher degree. Kidneys and urinary organs start to process the amniotic fluid that the babies intake and flush it outside again. This is a cycle of sorts that orients the body’s functioning in the right manner.

Apart from these, the endocrinal system and the spleen begin working too, while the muscles and bone structure continues to develop speedily.

What Is the Size of the Babies?

Around the 21st week of pregnancy, doctors usually start measuring the babies from head to toe, since their bodies would have begun to stretch themselves properly. This often puts children at a length of approximately 25 centimetres and would be lesser for multiples. Similarly, the weight also seems to be closer to 250-300 grams and can fluctuate for twins or triplets. Your little ones would now be as large as carrots inside your tummy.

What Is the Size of the Babies?

Common Bodily Changes

The 21st week of pregnancy is one of the key milestones biologically since it provides a strong signal for the babies as well as the mother to begin adjusting to the upcoming changes before delivery.

  • Although being so far deep into your pregnancy would have rid you of most anxiety and worry surrounding your babies, your body is still getting used to numerous changes happening within it. The only issue in the matter of the changes is that they are rarely in sync with each other, causing you to handle one after the other. While you may be looking forward to resting in the afternoon, you might be grappled with thoughts around your future and any other aspects concerning the babies. And if you finally end up being successful in putting yourself to sleep, your bladder may make you run to the toilet to pee frequently. Insomnia can strike many women in such situations, making them extremely restless.
  • If the creation of life for a woman is one of the mysterious processes, the cravings that ensue as a result of it might come as a close second. You might be well aware of the food items you wish to gobble and binge on in these previous months. However, as your little ones begin to initiate their digestion processes, these cravings could either stay the same or might sway entirely in a different direction. The babies now have a direct line to your food consumption via the amniotic fluid. Therefore, if their choices of food differ from yours, there is a good chance your body will signal you to have what the baby wants, which can get confusing.
  • You might continue to notice a transparent discharge from your vagina during this week or even later. While some women expect it to reduce, there usually isn’t the possibility for it. The discharge tends to increase up until you deliver your child since this is the perfect way the body ensures a hygienic vagina and a clean birth canal to keep the baby safe when it travels through it.

Common Bodily Changes

Symptoms of Twin Pregnancy at 21 Weeks

On one hand, you might be saying goodbye to the previous symptoms that you had initially. But from the 21st week, the teaser for what might arrive in the final trimester might begin to reveal itself to you.

  • Many women who are pregnant for the first time, and that too with twins or triplets, tend to freak out when they feel contractions early on in the pregnancy. Some women experience slight ones as soon as in the 17th week, while many tend to experience them from here on out. These contractions are termed as Braxton Hicks contractions. Usually lasting around half a minute or so, any change in orientation or positions tends to fade them away. Just the way the babies are practising different bodily functions, these contractions are your body’s way of exercising the process of childbirth.
  • The uterus has only one job which it continues to do without any interruption. It goes on expanding to make room for the babies that will soon be jostling for space inside it with their speedy growth. This expansion has also to be accommodated by your skin, which ends up in stretching and pulling itself. Stretch marks, which might have been only in a couple of body regions, might start being visible in other places, too. At times, these could even irritate the skin and cause itching, which can be taken care of with a light massage.
  • Yes, your breasts will also increase in size with your tummy, now that they know that your due date is approaching in a few months. While the growth usually reaches its full completion around the 24th week, early lactation might commence right now causing you to spot leaks around your nipples or in your bra intermittently.

Twin Pregnancy – Belly at 21 Weeks

Your baby bump will be visible now. In the case of multiple babies, since the skin stretches extensively, certain movements of the babies might be visible occasionally.

Twin Pregnancy at 21 Weeks – Ultrasound

Any ultrasound scans that were skipped in the previous week would be completed this week around, along with all the tests and checkups. Your babies would be visible very clearly, with occasional moments where you could see them swallowing and moving around, too.

What to Eat

What to Eat

When it comes to pregnancy, it is important that you stay healthy. No matter which week you are in, eating healthy foods and avoiding any foods that have an intense smell is important.

Pregnancy Care Tips

Most of the changes that occur in the 21st week of the pregnancy usually revolves around taking good care of your own body and setting up a habit routine to suit the latter months.


  • Undertake a screening test for glucose if you can to check for any conditions in advance.
  • Organize a baby shower or celebration if you can, since this would be one of those weeks where you’d still have your energy intact.


  • Binging on sweets should be a no-no since those could affect your baby as well as ruin the dental hygiene.
  • There’s no need to stop exercising entirely but you can tone down the intensity by this week.

What You Need to Shop For

Knowing that your babies are in sync with your progress, you can go a step ahead and purchase some necessary items, such as:

  • A moisturiser or a stretch marks cream for your skin.
  • Paraphernalia for the babies right from shampoos to baby oil and so on.

The development of twins at 21 weeks pregnant picks up its pace from this week. Reassure yourself that you will be ready for the babies when they arrive and keep your mental and physical health optimal to be at your best when the time comes.

Previous Week: Twin Pregnancy Week 20

Next Week: Twin Pregnancy Week 22

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