All 40 weeks·Trimester 2 weeks·Dashboard

Trimester 2 · Week 21 of 40

Week 21 of pregnancy: Feeling Movements

Why the size figure jumps this week, how blood-making moves to your baby's bone marrow, and telling normal swelling from swelling that needs a check.

Last updated 28 September 2026

What's happening this week?

Your baby's own bone marrow is beginning to make blood cells, and movements are becoming harder to miss. The length quoted this week looks much bigger than last week's because it is now measured head to heel. For you, the extra fluid your body holds often shows up as puffy ankles by evening, and some people notice tingling fingers or the first stretch marks. Most of this is expected, but sudden swelling of the face or hands is not, so it is worth knowing the difference.

Baby's development

Early in pregnancy, the liver and spleen make most of your baby's blood cells. From about 21–25 weeks, the bone marrow inside the growing bones begins to take over this job, and by the third trimester it is the main site of red-cell production, as it will be for life. Blood-cell production in the marrow keeps increasing through the rest of pregnancy.

Movements are now frequent and well coordinated. Many first-time mothers feel them clearly for the first time around now, often as taps, rolls or flicks, and you may notice that your baby is more active at certain times of day. That is the start of learning your baby's own pattern. There is no fixed number of kicks to aim for at this stage.

Your baby keeps swallowing amniotic fluid, and the gut is practising the work it will do after birth. Most of the fluid around your baby is now fetal urine, recycled continuously. Flavours from what you eat can reach the fluid, and taste buds are present, but claims that your baby is already forming food preferences go beyond the evidence.

Your baby's size

About the size of a papaya

26.7 cm

10.5 in · Length

360 g

Weight

Week 21

Gestational age

This week's 26.7 cm looks like a leap from last week's 16.4 cm, but it is a change of ruler, not a growth spurt. Charts switch from crown–rump to crown–heel length around 20 weeks, adding the legs. About 26–27 cm and 360–400 g are typical now, with plenty of healthy variation.

Your body this week

Your blood volume has risen substantially; studies estimate plasma volume is about 29% higher than before pregnancy at weeks 21–27. Plasma rises faster than red cells, which is why haemoglobin normally dips a little. Iron-deficiency anaemia is also very common in India, so keep taking your iron tablets and having your haemoglobin checked.

Your body is holding more fluid, and the growing uterus slows blood returning from the legs. Gradual swelling of the feet and ankles, worse in the evening and in hot weather and better after a night's sleep, is common. Fluid can also press on a nerve at the wrist, causing carpal tunnel symptoms: tingling, numbness or aching in the thumb and fingers, often worse at night. This usually settles within a few months after birth.

As your skin stretches, stretch marks may appear on the bump, breasts or thighs, often pink, red or darker than your skin tone at first. They are very common and are not harmful.

Symptoms you may notice

Every pregnancy is different - you may have some, all or none of these.

Swollen feet and ankles: Gradual swelling by evening is common. Rest with your feet up, avoid long standing and wear comfortable shoes. Sudden swelling of the face, hands or feet needs a same-day check for pre-eclampsia.
Tingling or numb fingers: Fluid pressing on the wrist nerve can cause carpal tunnel symptoms, often at night. Keep wrists straight in bed; a wrist splint can help. Mention it at your next visit.
Stretch marks: The skin is stretching over a growing bump. Moisturiser may ease dryness and itch; no product can guarantee prevention.
Varicose veins: Swollen, aching veins in the legs can appear as pressure rises. Raise your legs when resting and keep moving. A hot, red, painful area of one leg needs checking.
Itchy bump: Mild itching of stretching skin is common. Severe itching, or itching of the palms and soles, should be reported.

Medical care and tests

Routine antenatal check
Routine
India: second visit within 14 to 26 weeks
Blood pressure, weight, urine and haemoglobin are checked, along with your abdomen. If you have not had a second-trimester visit yet, arrange one. Tell your doctor about any swelling so they can judge it alongside your blood pressure and urine results.
Haemoglobin and iron
Routine
At antenatal visits
In India, anaemia is defined as haemoglobin below 11 g/dl. If yours is low, your doctor may prescribe a treatment dose of iron and recheck your level after about a month. Keep taking IFA and calcium tablets as prescribed.
Late anomaly scan
Only if needed
UK up to 23 weeks in some cases
If views were incomplete at the first anomaly scan, some centres repeat part of it now, often because the baby's position hid part of the anatomy. Ask whether your report needs any follow-up and when it should happen.

Free antenatal check-ups for women in the second and third trimesters are available at government facilities on the 9th of each month under PMSMA, including haemoglobin checks.

Nutrition this week

Salt and fluids are this week's focus. Use iodised salt as ICMR-NIN advises, but go easy on salty extras such as pickles, papad, packaged namkeen, chips and instant noodles.
Keep drinking well even if your ankles are puffy. ICMR-NIN advises more than 2 litres of fluid a day, from water, chaas, soups and dal.
Coconut water can be one of your drinks, but it does not increase amniotic fluid or change your baby's skin colour; those are myths.
With blood volume rising, keep iron foods coming: rajma, chana, masoor, soya, bajra and green leafy vegetables, paired with amla, guava, tomato or lemon.
Keep tea and coffee at least an hour away from meals and from your iron tablet.

Movement and exercise

Walking and swimming both help circulation in the legs. Water-based exercise can feel especially comfortable when your ankles are swollen, because the water supports your weight.
When sitting, circle your ankles and point and flex your feet every so often. Avoid crossing your legs for long periods, and try lying on your side with a pillow under your feet for a short rest.
Stop and check with your doctor if one leg becomes painful and swollen, or if swelling appears suddenly.

Things to keep in mind

Take off tight rings before your fingers swell and wear loose, comfortable shoes and socks without tight bands.
If you stand at work, ask for a stool or regular short breaks to sit with your feet up. In hot weather, stay in the shade and keep cool, since heat can make swelling worse.
Tracking your weight gain can help you and your doctor spot changes early; gradual gain is expected now.
Avoid ibuprofen or diclofenac gels and tablets for hand or joint pain unless your doctor advises; ask about safer options.

When to contact your doctor

Call your doctor or midwife the same day if you have

Sudden swelling of your face, hands or feet.
A headache that will not go away.
One leg painful, red, warm or much more swollen than the other.
Numbness or weakness in the hand that is getting worse.
Any vaginal bleeding.
Burning when passing urine, or a fever of 38°C or more.

Get emergency care now if you have

Severe headache with vision changes, or pain below the ribs on the right.
A fit (seizure).
Bleeding that soaks a pad, or abdominal pain that is severe.
Chest pain or sudden breathlessness.

In India, call 108 for an ambulance, 102 for free transport for pregnant women in many states, or 112 for any emergency - or go straight to your nearest hospital with a maternity unit.

If something feels wrong, trust that feeling and call - you never need to wait for your next appointment.

Questions to ask your doctor

Is the swelling I have normal, given my blood pressure and urine results?
What was my latest haemoglobin, and do I need a higher iron dose?
Would a wrist splint help my tingling fingers?
Does my anomaly scan need any follow-up views?

Week 21 checklist

Feet raised for a rest each afternoon
Rings removed if fingers feel tight
Haemoglobin result noted from your last visit
Salty snacks cut back, iodised salt kept
More than 2 litres of fluid most days

Frequently asked questions

Why did my baby's length suddenly jump from last week?

Your baby did not grow ten centimetres in a week. Until about 20 weeks, length is measured from head to bottom, because the legs are curled up. From around 20 weeks, many charts switch to head-to-heel length, which adds the legs. Your baby's growth is steady; only the measuring method changed.

How do I know if my swelling is normal?

Swelling that builds slowly through the day, mainly in the feet and ankles, and improves overnight is common. Swelling that appears suddenly, especially in the face or hands, or comes with a headache, vision changes or pain under the ribs, can be a sign of pre-eclampsia. Get checked the same day, and treat severe symptoms as an emergency.

Can I prevent stretch marks with oils or creams?

Many oils and creams are sold for this, but do not expect any product to guarantee prevention, and there is no need to spend a lot. A plain moisturiser can ease the dryness and mild itching of stretching skin. Stretch marks are common and harmless. Itching of the palms and soles is different and should be reported.

This page is general information, not a diagnosis or a substitute for care from your own doctor or midwife. Pregnancies differ, and timings here are typical ranges rather than deadlines. Read our medical disclaimer and editorial policy.