21st Week Pregnancy: Symptoms, Baby Development, And Tips

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How Many Months Are 21 Weeks Of Pregnancy?

At 21 weeks, you are in the fifth month of pregnancy. By now, you would’ve felt your baby move a little, although these movements are infrequent and feel like you have butterflies in the stomach.

Here, MomJunction tells you more about how your body changes and your baby grows in the 21st week.

How Big Is Your Baby At 21 Weeks?

In the 21st week, your baby is about the size of a carrot and measures 10.51in (26.7cm) in length and weighs 12.7oz (360g) (1) (2).

What Is The Baby’s Development At 21 Weeks?

Here is how your baby’s body is developing in this week:

Body parts Developmental stage
EarsThe baby starts responding to sounds
Eyes (3)Eyebrows and eyelashes are developing
Digestive systemStarts working
SkinCovered with a waxy coating called vernix
PlacentaKeeps growing
Lanugo (4)The body is covered with soft, fine hair
Mouth (5)Taste buds develop, and the baby starts swallowing amniotic fluid
Circadian rhythms (6)Heart rate, breathing pattern, and body movements follow a rhythmic pattern
Liver and spleen (7)Make blood cells
Bone marrowDeveloped and contributes to blood cell formation
LimbsThe kicks get stronger, and the baby constantly moves inside the womb
GenderCan be determined through an ultrasound scan

As the baby grows and develops new functions, you will experience certain symptoms. Read about that next.

What Symptoms Do You Experience In The 21st Week Of Pregnancy?

Here are some common symptoms you might experience during this week:

  1. Weight gain: It should be based on your BMI (8).
BMIBelow 18.518.5 – 24.925 – 29.930 and Above
RECOMMENDED WEIGHT GAINAbout 13 Kg11- 16 Kgs7-11kgs5-9kgs
  1. Heartburn/indigestion: The gastric fluids in the stomach are pushed up into the esophagus due to the pressure exerted by the growing uterus, causing heartburn.
  1. Braxton Hicks contractions: These are irregular, spontaneous, and less painful contractions that help prepare the body for labor.
  1. Increased appetite: The hunger pangs may increase, so have small meals at frequent intervals. Pack snacks or fruits for your office and eat them whenever you are hungry.
Hunger pangs may increase when pregnant

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  1. Fast-growing nails: The hormonal changes and increased blood circulation provide extra nutrients to your hair and nails and make them grow faster.
  1. Backache: The extra weight of the baby puts pressure on the lower back causing backache.
  1. Physiological edema: Water retention in the body causes swelling of hands and feet.
  1. Frequent urination: The pressure exerted by the growing uterus on the bladder increases the frequency of urination.
  1. Varicose veins: The extra blood flow to the lower part of the body causes the veins to swell.

Tip: Keep the legs elevated and avoid standing for long hours. Maintain a healthy weight during pregnancy and add more fiber to your diet to avoid constipation.

  1. Urinary tract infection (UTI): The extra pressure put on the bladder by the growing uterus can block the urine flow, causing UTI. Symptoms of UTI include:
UTI is common when 21 weeks pregnant

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  • Pain or burning sensation while passing urine
  • Fever
  • Chills
  • Urinating more frequently than before
  • Pain or cramps in the pubic area
  • Foul smelling or turbid urine

Tip: Drink plenty of water. Avoid holding urine for long as it promotes bacterial growth in the urinary tract.

What Changes Occur In The Body At 21 Weeks Of Pregnancy?

  1. Enlarged belly: As the baby attains good growth by this week, the uterus enlarges and your belly bump shows.
  1. Enlarged breast: The breasts grow in size as the body starts preparing for milk production.
  1. Blue veins: The veins surrounding the breasts become more prominent due to an increased blood supply.
  1. Colostrum leak: The yellow fluids (the first milk) may start leaking from the nipples.
  1. Oily skin and acne: The hormonal changes cause excess production of sebum (oil produced from skin), resulting in acne.
You may have oily skin and acne at 21 week pregnancy

Image: Shutterstock

Tips: Clean the face with lukewarm water and use oil-free creams and cosmetics. Wash your hair daily or as often as needed to remove the excess oil.

  1. Stretch marks: The skin stretches with the growing uterus, creating stretch marks. The skin may also become dry and itchy. Applying a good moisturizing lotion can help reduce the itchiness.

The symptoms you experience now are not all pleasant. But if they are making you uneasy, talk to your doctor about them during the regular prenatal visit.

What Is Your OB/GYN Visit Like?

In this week, the doctor will check the:

  • Blood pressure
  • Weight gain
  • Fundal height
  • Fetal heart rate

The doctor may also recommend a urine test, besides other tests, to determine the protein and sugar levels.

What Tests Are Done In The 21st Week?

  1. Anomaly scan: Done between 18 weeks and 20+6 weeks, this ultrasound scan determines the physical abnormalities in the baby (9) It can check for 11 physical conditions including:
Anomaly scan is done when you're 21 weeks pregnant

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  • Open spina bifida
  • Anencephaly
  • Diaphragmatic hernia
  • Cleft lip
  • Exomphalos
  • Gastroschisis
  • Cardiac abnormalities
  • Lethal skeletal dysplasia
  • Bilateral renal agenesis
  • Patau’s syndrome or T13
  • Edwards’ syndrome or T18

All anomalies cannot be detected by this scan; the detection rate is 80%.

  1. Maternal serum quad screen (10): This screening test will be done if you have missed the sequential screening tests in the first trimester. It checks for the level of four substances in the blood like alpha-fetoprotein (AFP), estriol, human chorionic gonadotropin, and inhibin-A. These tests detect Down syndrome and neural tube defects in babies (10).

Make sure you get all the recommended tests done and follow a healthy lifestyle. Next, we have a few tips on how to stay healthy this week.

What Are Some Tips For Moms-To-Be?

Here are some tips for you to follow during this week:

  • Drink plenty of water to stay hydrated.
  • Eat small meals at regular intervals and have home cooked food.
  • Add fruits, vegetables, dairy products, beans, and meat in the diet. Some recipes you can add to your diet include celeriac and watercress soup, and sweet apple lamb.
  • Exercise moderately; walking is ideal to keep up your energy level.
  • Maintain oral hygiene by brushing and flossing your teeth regularly.
  • Avoid smoking, drinking alcohol, and using illicit drugs, as it can affect the growth of the fetus.
  • Keep stress at bay.
  • Wear loose, breathable clothes.
  • Give your body enough rest.
  • Do not take any medicines without the doctor’s permission.
  • Avoid sitting with your legs crossed as it can cause a backache.
  • Avoid oily and fatty foods and add more fiber to your diet. It helps reduce constipation.
  • Wear comfortable footwear.
Wear comfortable footwear when pregnant

Image: Shutterstock

  • Avoid sitting for long hours if you are working. Try to get up and walk around the office as often as you can.
  • Enroll in childbirth classes to prepare for labor and delivery.
  • Spend time with family and friends.

Whenever needed, seek your partner’s help and support.

What Are Some Tips For Dads-To-Be?

Here are some tips for the dad-to-be:

  • Share the household chores to lessen your burden.
  • Create a pleasant environment at home.
  • Accompany you to all prenatal visits.
  • Go for maternal shopping or plan a romantic date.
  • Give you a good neck or foot massage to ease your discomfort.

Frequently Asked Questions

1. What pains are normal at 21 weeks pregnant?

If you are 21 weeks pregnant, you may experience (11) (12)

  • Round ligaments pain caused on the sides of your bump due to the expanding uterus
  • Breast pain
  • Sharp pain in the abdomen that may travel to your thighs
  • Back pain
  • Pain due to hemorrhoids
  • Sharp pain in the legs

2. Why is my stomach so tight at 21 weeks pregnant?

Your stomach may feel tight if you experience Braxton Hicks contractions. During these contractions, the uterus tightens, making your stomach also feel tight and firm (13).

Another cause of tightness in the stomach may be a condition called polyhydramnios, where the excess amniotic fluid collects in the uterus. This makes the uterus larger than normal, leading to a tight stomach (14).

3. What is the position of my baby at 21 weeks?

At 21 weeks, your baby is small and may frequently be changing positions in the uterus (15). The position of the baby is not fixed.

You are halfway through your pregnancy at 21 weeks and may experience a slew of physical and emotional changes. You may also gain some weight and experience increased appetite, heartburn, backache, and an urge to urinate frequently. However, keep yourself calm, eat a balanced diet, and drink plenty of water. In addition, exercise moderately and avoid drinking alcohol and smoking. Though uneasiness is common during this time, do not let it take a toll on your mental health. Instead, find ways to stay stress-free and engage in safe leisurely activities.


MomJunction's articles are written after analyzing the research works of expert authors and institutions. Our references consist of resources established by authorities in their respective fields. You can learn more about the authenticity of the information we present in our editorial policy.
  1. Week by Week Fetus Size Demonstrated by Fruits.
  2. Fetal Development.
  3. Stages of pregnancy.
  4. You and your baby at 21 weeks pregnant.
  5. Baby’s Palate And Food Memories Shaped Before Birth.
  6. Prenatal Summary.
  7. Week 21.
  8. Pregnancy Weight Gain.
  9. 20-week screening scan.
  10. Prenatal Genetic Testing.
  11. Week-by-week guide to pregnancy.
  12. Pregnancy Discomforts: Back Pain Round Ligament Pain Nausea.
  13. Stomach Pain in Pregnancy.
  14. Polyhydramnios.
  15. Your pregnancy: weeks 21 to 24.
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shreeja pillai

Shreeja holds a postgraduate degree in Chemistry and diploma in Drug Regulatory Affairs from the University of Mumbai. Before joining MomJunction, she worked as a research analyst with a leading multinational pharmaceutical company. Her interest in the field of medical research has developed her passion for writing research-based articles. As a writer, she aims at providing informative articles on health...
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Subhashis Samajder

( MS, DNB)
Dr. Subhashis Samajder is a consultant Gynecologist-Obstetrician currently practising at Narayana Multispeciality Hospital, Howrah. His area of expertise includes abortion, colposcopy surgery, hysterectomy, hysteroscopy, infertility treatment, and menopausal problems. Dr. Samajder believes in sending his patients back home healthy and satisfied with the treatment. He also takes up women’s health awareness through his YT videos.