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Your 21-Week-Old Baby – development & growth

Table of Contents

21-Week-Old Baby

Table of Contents

Learning more about the constantly evolving baby eyesight, whole solid baby foods, and how to make your picky eater nourishing, nurturing, and yummy solid food purees at home.

Your baby's twenty-first week after birth

At 21 weeks, your baby will display remarkable developments both physically and mentally. Your little one’s hearing and vision will continue to improve. Try calling out their name because they’ll look in your direction. Also, your baby will start to show a wide range of emotions such as enjoyment, pleasure, anxiety, irritability, and boredom. By now, your baby might start showing some uneasiness when you get separated from them. If you pass your baby onto someone else, they could start crying. If this happens, give adequate time to your baby to become familiar with new people. 

It’s almost time for your little one’s first words! Usually, your baby will try to duplicate the sounds that they hear.

Your 21-week-old baby's development and physical growth

Your baby’s weight:

  • Due to the continuous diet of breast milk or formula and solids, your little boy will weigh around 13 to 23 pounds and measure around 24 to 29 inches.
  • Whereas your little girl will weigh around 12 to 22 pounds and measure around 23 to 28 inches.

Your baby’s diet:

  • Your little one’s appetite is likely to increase. 
  • At 21 weeks, your baby should have around 24 to 30 ounces (up to 32 to 36 ounces at most) of breast milk or formula over 24 hours.
  • Plus, it’s time to introduce solids to your little one!
  • You can start with 1 to 2 tablespoons to 3 to 9 tablespoons of cereal, fruit, and vegetables. 
  • Moreover, as you’re introducing solid food, offer just one at a time. 
  • Give your baby that one food for a couple of days as it helps to determine if it’ll cause an allergic reaction.
  • Also, don’t force the food, if your baby is crying, not interested, or turn their head away from it. 
  • As of now, simply go back to your usual bottle or breastfeeding schedule.
  • You can start trying a couple of days later.
  • Remember to give your baby time to get used to it. 
  • You can start with just a teaspoon or two until they get the hang of keeping the food in their mouth. 
  • Remember, to not stress about the amount of solid food your baby is eating. 
  • Your little one still gets the nutrition they need from breastmilk and/or formula.

Your baby’s sleep:

  • 21-week old babies need sleep about 11 hours during the night and around 2 daily naps that add up to 3 to 4 hours. 
  • Remember this can vary because every baby is different. 
  • Although there’s a sudden change in your baby’s sleep pattern, it might start getting regular. 
  • Here are some key points about your 21-week-old baby’s sleeping patterns:
    • During the nighttime, they might not sleep throughout it but might sleep for longer hours.
    • If they wake up during the night, simply breastfeeding your baby will help them settle down and get back to sleep.
    • Their naps are going to be chunkier (around 45 min) instead of frequent small naps throughout the day.
    • Do not feed your baby too much before sleep time. Overfeeding can lead to colic and might cause added wakefulness.
    • At 21-week-old babies usually have sleep regression. Due to growth spurts, your baby might undergo sleep regression. They might unexpectedly begin to wake up in the night or develop napping issues.

Your 21-week-old baby's reflexes

Babies develop at their own pace and the developmental milestones for every baby will be different.

  • By now, your little one’s taste buds are more developed so you can expect your baby to put random objects that they can hold into their mouth.
  • By this week, some babies might be sitting. However, while sitting up most babies might still need some support.
  • Your little one’s vision is constantly improving. By now, they could be able to focus on small-sized and moving objects.
  • Their muscles are getting stronger. For some tummy time, your baby might be able to roll over to their side or flip over.
  • You might notice that your little one is adding new sounds to their typical babble, such as a gurgle or a squeak. Also, you’ll more often see your baby repeating sounds that they get to hear around them.
  • It’s time to bring out your funny faces and weird sounds! Because your little one will more likely laugh at or enjoy them.
  • Additionally, some babies will begin teething as of this week. Be on the lookout for the symptoms of teething. You can expect to see some excessive drooling, swollen gums, heightened irritability, etc.

Your 21-week-old baby's health

Here are some tips to ensure that your 21-week old baby is healthy and growing appropriately:

  • As your little one is capable of rolling or flipping themselves over, be sensible and opt for ground settings or mattresses to prevent any falls or accidents.
  • In case your baby starts teething, offer some soothing and safe teething toys or rings to your baby.
  • Make sure their toys are sterilized as they are more likely to put them in their mouth.
  • Whenever your little one is playing with small objects or toys that can come loose, keep an eye on your baby as they can be choking hazards.
  • Remember to childproof your house and get rid of anything that’ll cause accidents.
  • Your little one might start drooling too much. So, keeping a good supply of bibs can come in handy.
  • Change your baby’s soiled diaper, clean the area properly and allow your baby to remain without diapers for some time every day. This will prevent diaper rash.
  • If you missed any of your little one’s 4-month immunization vaccinations, scheduling an appointment with your doctor should be on top of your priority list.

Postpartum baby tips: Week 21 after birth

Understanding your baby’s immune system

  • Your 21 weeks old baby’s immunity is not fully developed as of yet. 
  • This makes your little one vulnerable to the common cold and flu. 
  • If your little one has a runny nose, fever, or is constantly crying, you should consult a doctor. 
  • Babies are also prone to colic.
  • If you feel something is amiss, follow your mother’s instinct and consult a pediatrician.

Understanding your baby’s eyesight

  • At this age, your little one’s eyesight is constantly evolving. 
  • The American Optometric Association stated that babies have a good color vision by month five. 
  • The bold, bright toys, that were taking over your house, are extra exciting for your little one.
  • You can add some rotating mobiles to the list. 
  • When your baby is chilling in their crib, he’ll love watching bright shapes move over their head. 
  • You can attach some colorful toys to the stroller bar.

The parents after childbirth: What is happening in the twenty-first week after giving birth?

You’re making your baby food

  • When you’re on the go, baby food jars and pouches come in handy however, store-bought food is quite expensive. 
  • Fortunately, it’s pretty easy to make your own. 
  • Now, you can control the ingredients and quality added to your baby’s food. 
  • Also, you can get fun and creative and see your baby delight in your latest combos. 
  • Plus, sneak in some spinach while you’re at it.
  • The type of gadget you go with does not matter. 
  • The process to make some food for your little one is the same: Simply prep food, then steam it, and finally puree or chop it. Viola, you’re done!
  • Make sure you’ve wipes within arm’s reach because things are about to get messy!

Your baby’s first words

  • At this stage, you’ll be able to hear the sweet you were waiting for. 
  • Any day now, your little one will be uttering their first blessed word (hopefully “mama”).
  • You might’ve noticed your babies imitating the sounds they hear from their loved ones.
  • Also, they’re exploring their communication abilities. 
  • Whenever you talk to your baby, make sure they can see your face. 
  • This way they’ll watch your lips move and attempt to do the same.
  • Eventually, your baby will start imitating everything you say. 
  • So remember to keep the colorful language to a minimum. 
  • The last thing you want is for your baby to say something that they shouldn’t.

Final Thoughts

You’ll be able to see some exciting changes in your little one during this week. You can delightfully watch your baby try to pull themself into a sitting position or attempt to crawl. You might notice your little one responding or showing affection towards you. You might experience some truly heartwarming moments like your baby stretching out their arms to be lifted or when you pick them up, they’ll embrace you affectionately. Embrace yourself because there’ll be more moments to come! 

Sometimes this journey can be tiring or overwhelming, but it’s worth it! As your little one is growing out of it soon, try and spend as much time as possible to bond with your baby. Enjoy the joys of motherhood!

FAQs- Your 21-Week-Old Baby: Development & Growth

1. How do you know if your baby is having a growth spurt?

If your little one is suddenly hungrier and crankier than usual they could be having a growth spurt. Also, one day, your little one might fit into that sweet little onesie, and the next day, they don't. It might not be your sleep-deprived eyes playing tricks on you.

2. What can babies do at 21 weeks old?

At 21 weeks, your little one is setting up the foundation to crawl and sit in the next few months. Moreover, this will increase their appetite.

3. What are some games and activities that you can enjoy with your 21-week old baby?

Here are some games and activities that you can enjoy with your 21-week old baby:
  • Ground time - Let your baby enjoy playing on a baby play mat.
  • Sitting up - Help your little sit up with some pillow around them.
  • Trace the direction of the sound - Get your little one to look at the rattling sound made by toys or music.
  • Sounds - Talk to your baby frequently so that they can pick up on sounds and imitate you.
  • Keep them entertained - Use some bright colored toys (preferably something to chew on), musical toys, roly-poly toys, etc. to hold your baby’s attention.
  • Baby games - Play peekaboo, the little piggy, itsy bitsy spider, where is the toy/object, etc.
  • Reviewed By-

    Nimrat, Pediatrics

    Nimrat, Pediatrics

    Dr. Nimrat S Sidhu is a practicing pediatrician for about 5 years now and holds an MD pediatrics degree. She was the topper of her batch, has always had a keen interest in her core medical field, and is specially trained for neonatal resuscitation.

    On behalf of the editorial team at Parenthoodbliss, we follow strict reporting guidelines and only use credible sources, along with peer-reviewed studies, academic research institutions, and highly respected health organizations. To learn about how we maintain content accurate and up-to-date by reading our medical review and editorial policy.

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