21 Weeks Pregnant: Common Symptoms, Baby Development, And Size

21 Weeks Pregnant: Common Symptoms, Baby Development, And Size

20 Dec 2016 | 11 min Read

Sudeshna Chakravarti

Author | 75 Articles

At 21 weeks pregnant, your baby has more control over their limb movements, which is why, starting this week, you will experience more kicks and wiggles. These light movements may feel like butterflies in your stomach and may occur several times a day.

In terms of physical changes, you may notice more prominent stretch marks, which appear purple or reddish-brown in colour and mostly form around your stomach, as a result of your expanding belly. In addition, you will continue to experience pregnancy symptoms like heartburn, indigestion, and body aches.

In this post, we tell you more about the common symptoms and bodily changes experienced during the 21st week of pregnancy, and also discuss your baby’s weekly developmental and growth progress.  

Your Baby’s Development at 21 Weeks

At 21 weeks of pregnancy, you are officially five months pregnant and have only four months to go till you see your little one. During this week, your baby’s organs will continue to develop and your belly will expand more with your navel protruding outward. 

By this week you will also notice a jump in your baby’s length, as your ob-gyn will now begin to measure them from crown to heel, instead of the crown to rump.

Keep reading to know more interesting facts about your baby’s progress in the 21st week of pregnancy.

How Big is Your Baby at 21 Weeks?

At 21 weeks of pregnancy, your baby will be about the size of a carrot, measure 26.7cms (10.51 inches) in length and weigh around 360gms (12.7 ounces). 

If you want detailed insight into your baby’s weekly development, size, and growth progress, you can follow the posts under pregnancy-week-by-week by BabyChakra. These posts contain relevant information that answers all your questions about your little one’s progress and also discusses what symptoms and bodily changes you may experience every week.

Foetal Development at 21 Week Pregnancy

21 weeks pregnant
During the 21st week of pregnancy, your baby’s digestive system will be formed and they will start swallowing a bit of amniotic fluid / Image source: Medical News

In this section, we have discussed how your baby’s body develops inside the womb at 21 weeks of pregnancy and what growth milestones you can expect them to achieve this week.

  • Skin: Your baby’s skin is covered with a waxy coating called vernix.
  • Eyes: Your baby’s eyebrows and eyelashes continue to develop. Their retina is also forming and they can respond to a beam of light.
  • Ears: Your baby will start responding to sounds now. So make sure you are communicating with them and also singing to them.
  • Digestive system: By the 21st week of pregnancy, your baby’s digestive system will begin to function.
  • Lanugo: Your baby’s body will be covered with soft, fine hair, which is referred to as lanugo. This hair will mostly shed on its own after birth.
  • Placenta: Your placenta keeps growing in proportion to your baby’s size, and it also continues to deliver essential nutrients and vitamins to your little one.
  • Mouth: Your baby’s taste buds develop and they can now differentiate between sweet and bitter tastes. By this week, your baby starts to swallow a little bit of amniotic fluid.
  • Liver and spleen: Your baby’s liver and spleen work to produce blood cells.
  • Circadian rhythms: During this week, your baby’s breathing pattern, heart rate, and body movements begin to follow a rhythmic pattern.
  • Limbs: Your baby will now constantly move its hands and legs inside the womb, with its kicks getting stronger with each passing week.
  • Bone marrow: The bone marrow is fully developed by this week and contributes to blood cell formation.
  • Gender: The doctor can determine the gender of the baby through an ultrasound scan.

Common Symptoms That You Will Experience This Week

21 weeks pregnant
In the 21st week of pregnancy, you will experience symptoms like back pain, Braxton Hicks contractions, and frequent urination

At 21 weeks of pregnancy, you will experience symptoms similar to the early signs of pregnancy and also the ones experienced during the earlier weeks. The symptoms experienced this week include:

  • Heartburn or indigestion: The growing uterus exerts pressure on the abdomen, causing the gastric fluids to push upwards into the oesophagus. This causes heartburn or indigestion and can be prevented by avoiding spicy, oily, and processed foods.
  • Weight gain: During pregnancy, it’s normal to gain a certain amount of weight. But make sure that your weight gain is healthy and coincides with your BMI. Your ob-gyn will do a weekly/monthly weight check and suggest dietary modifications in case you are underweight or overweight.
  • Braxton Hicks contractions: In the 21st week of pregnancy, you will also experience Braxton Hicks contractions, which are infrequent, spontaneous, and less painful contractions that help prepare your body for labour.
  • Fast-growing nails: During this time, the increased blood circulation and hormonal changes provide additional nutrients to your nails, making them grow faster than usual.
  • Increase in appetite: By this week, you may notice an increase in hunger pangs. So have smaller meals at frequent intervals. Pack snacks and fruits for your office, and munch on them when you are hungry.
  • Physiological edema: Edema is a common symptom experienced during this time, where water retention in your body causes swelling in your hands and feet.
  • Backache: The extra weight of your baby puts pressure on your lower back, causing backache. To prevent back pain, maintain proper posture, and support yourself with pillows while sitting.
  • Varicose veins: During this time, there is extra blood flow to the lower part of your body, causing your veins to swell. You can keep your legs elevated and avoid standing for long hours to alleviate the pain. Also, support your legs with comfortable pillows while sleeping.
  • Frequent urination: The expanding uterus puts extra pressure on your bladder, increasing your urge to pee.
  • Urinary tract infection: The extra pressure put on your bladder by the growing uterus can sometimes block the urine flow, causing UTI. Some of its symptoms include pain while passing urine, fever, chills, and cramps in the pubic area. In case you notice experience these symptoms, consult your doctor right away. 

Your Body at The 21st Week of Pregnancy

The bodily changes that occur in the 21st week of pregnancy are much different than those felt in the first trimester. You can expect the following bodily changes as you hit the five-month pregnancy mark.

  • Enlarged breasts: Your breasts will grow in size as your body prepares for milk production.
  • Enlarged belly: Your baby will attain good growth by this week, causing your uterus to expand, and resulting in an enlarged baby bump.
  • Stretch marks: With the uterus growing each week, your skin undergoes small tears, creating stretch marks on your belly. You may also experience itchy and dry skin during this time. Applying a nourishing moisturiser or lotion can hydrate and soothe your skin.
  • Oily skin and acne: The hormonal fluctuations in your body cause excess sebum production, resulting in oily skin and acne.
  • Blue veins: The veins surrounding your breasts become more prominent due to an increase in blood supply.
  • Colostrum leak: During this week, the yellow fluids (referred to as the first milk) may start to leak from your nipples.

21 Weeks Pregnant Belly

At 21 weeks, your belly will appear protruded and as your little one has sufficient place to move inside the womb, you will also notice an increase in their kicks and movements. Also, as your baby has more control over their limbs, their movements will start to become more coordinated this week.

If you want to know more about your baby’s activity in the womb and how it progresses each week, you can use the pregnancy month calculator to find out more details and information.

Do You Need an Ultrasound at The 21st Week Of Pregnancy?

When you are 21 weeks pregnant, you will have a set of physical checkups during your prenatal visit.  The ob-gyn will check your blood pressure, weight gain, fundal height, as well as foetal heart rate. 

In addition to these tests, the ob-gyn will also suggest an ultrasound or anomaly scan, which detects the possibility of any physical abnormalities in your baby. The scan checks for several physical conditions, including cleft lip, diaphragmatic hernia, cardiac abnormalities, and anencephaly.

Self-care Tips for 21 Weeks Pregnancy

21 weeks pregnant
Make sure to get plenty of rest during this time to maintain good health

To maintain optimal health and well-being, follow these essential self-care tips in the 21st week of pregnancy.

  • Add fresh fruits, veggies, fish, dairy products, and legumes to your diet. These foods are fibre-rich and prevent conditions like constipation.
  • Drink 8-10 glasses of water to keep yourself hydrated throughout the day.
  • Have smaller but more frequent meals to prevent indigestion or heartburn.
  • Engage in moderate physical activities, such as walking and prenatal yoga to keep up your energy level.
  • De-stress and give your body enough rest.
  • Read pregnancy and maternity books to learn more about labour and childcare. 
  • Try to wear loose clothes for added comfort. Also, switch to good-quality slippers or shoes that support your weight and keep leg pain at bay.
  • Avoid consuming fatty and spicy foods, and stick to eating home-cooked meals.
  • Don’t sit in one position for long hours. Try to stand up and walk frequently to prevent back pain and leg cramps.
  • Indulge in activities that make you happy.

Pregnancy Checklist at 21 Weeks

 A set of checklists for the 21st week of pregnancy:

  • Make an appointment with your sonographer for the next ultrasound scan.
  • Schedule your next prenatal appointment with your ob-gyn.
  • Prepare your baby’s nursery and purchase essential baby care items.
  • Make a list of questions that you may want to ask your doctor during the next appointment.

What to Ask Your Doctor?

By the time you reach your 21st week of pregnancy, your baby will be rapidly growing, and you may feel curious about its progress in the upcoming weeks and the common pregnancy symptoms that you may experience. Some crucial questions to ask your doctor include:

  • Will I experience any new symptoms the next week?
  • What growth milestones will my baby achieve in the next week?
  • Is my baby growing healthily?
  • Is it safe for me to exercise in the coming weeks?
  • How many hours of sleep should I get per day?
  • Do you suggest any additional tests for the next week?


When you are 21 weeks pregnant, you may experience a slew of physical and emotional changes, increased appetite, weight gain, mood swings, and anxiety. While some of these symptoms can feel uneasy, your main focus should be to get adequate rest and follow a healthy lifestyle to maintain good health and support your little one’s growth.


How many months are 21 weeks pregnant?

21 weeks pregnant means that you’ve hit the five-month pregnancy mark, and have just four months left to meet your baby.

Is 21 weeks pregnant equal to 5 months of pregnancy?

Yes, 21 weeks pregnant roughly equals five months of pregnancy.

What should I be doing during 21 weeks of pregnancy?

You should be following a healthy lifestyle, engaging in moderate exercises, visiting your ob-gyn regularly, and taking adequate rest during 21 weeks of pregnancy.

Can I feel my baby’s kicks at 21 weeks?

Yes. Since your baby has more control over their limb movements now, you can feel an increase in their kicks by this time.

Can you see the baby’s kicks in the ultrasound?

Yes. You will be able to see your baby kicking during an ultrasound. You may also notice them sucking their thumb in the scan.

When does the 6th month of pregnancy start?

The sixth month of pregnancy starts from week 23 of pregnancy. 

Also read:

22 weeks pregnant symptoms: Check out this post to learn all about the different symptoms experienced in the 22nd week of pregnancy.

Ovulation calculator: Do you know the benefits of using an ovulation calculator for planning a pregnancy? Check out this post for details.

Featured image: Freepik.com











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