Pregnancy › Week by Week › Week 21
At 21 weeks your baby is about the size of a carrot, and moving with more coordination. You are past halfway and into a lively stretch of pregnancy.
Size
A carrot
head to heel
Length
10.5 in
about 26.7 cm
Weight
12.7 oz
about 360 g
Your baby at 21 weeks
Movements are more coordinated, taste is developing, and the body is learning to make its own blood cells.
Your baby is more active and more capable this week, with steady practice going on behind the scenes. Everything is trending toward the newborn to come.
Movement. Arm and leg movements are stronger and better coordinated, so kicks and rolls are becoming something you feel more regularly. Your baby has more room to move for now, which is part of why the movements can feel so varied.
Taste and swallowing. Your baby swallows small amounts of amniotic fluid, which is good practice for the digestive system, and taste buds are developing. The flavors of what you eat can pass into the fluid, so your baby is getting an early sense of taste.
Inside. The bone marrow is taking over the job of making blood cells, joining the liver and spleen that handled it earlier. It is a quiet but important milestone in how your baby’s body runs itself.
How big is your baby at 21 weeks?
About 10.5 inches (26.7 cm) head to heel and roughly 12.7 ounces (360 g).
From around week 20 your baby is measured head to heel rather than crown to rump, because the legs are now stretched out enough to include. That is why the length numbers took a jump recently. From here the measurement stays head to heel for the rest of pregnancy.
Your body at 21 weeks
Regular kicks, a healthy appetite, and a few of the aches that come with a bigger bump.
Many people are feeling regular movement now, and it is reassuring to start noticing your baby’s busy and quiet times. Your appetite is likely back in full, so steady, balanced meals help more than grazing on empty calories. You may also start to notice Braxton Hicks, occasional painless tightenings of the uterus that are simply your body practicing. They come and go and should not be regular or painful.
With the bump growing, stretch marks may appear on the belly, hips, or breasts as the skin expands, the occasional sharp pull of round ligament pain can catch you when you move quickly, and swelling in the feet and ankles is common by the end of the day. Keeping skin moisturized keeps it comfortable, and roomy maternity clothes make a real difference now. Putting your feet up when you can helps with the swelling.
What is normal, and when to call your provider
Most twinges are normal at 21 weeks, but call your doctor or midwife the same day if you have any of these:
- Regular tightening or cramping, low back or pelvic pressure, or more than four contractions in an hour
- A gush or steady trickle of fluid, or any vaginal bleeding
- A severe or lasting headache, changes in your vision, or sudden swelling of the face and hands
- A noticeable drop in movement once you are regularly feeling your baby
- Burning when you urinate or a fever over 100.4°F (38°C)
Your week 21 checklist
- Start getting to know your baby’s active and quiet times as movement becomes regular
- Keep taking your prenatal vitamin every day
- Moisturize the growing bump and wear comfortable maternity clothes
- Sleep on your side with a pregnancy pillow for support
- Put your feet up when you can and stay hydrated to ease swelling
Appointments and tests around 21 weeks
This is usually a quieter stretch between the anatomy scan and the glucose screening.
If your anatomy scan happened at 18 to 20 weeks, week 21 often has no special test, just your routine prenatal check where your provider measures your bump, checks your blood pressure, and listens to the heartbeat. It is a good time to bring up any questions about movement, Braxton Hicks, or aches. Glucose screening for gestational diabetes usually comes a little later, and if your anatomy scan is still to come, it can happen around now. Otherwise, use these calmer weeks to rest and enjoy feeling your baby move.
A few things worth having on hand now
A note for your partner
Kicks are getting strong enough that you may be able to feel them from the outside soon. Rest a hand on the bump in the evening when your baby tends to be active, and be patient, they move on their own schedule. Feeling that first kick against your palm is a moment worth waiting for.
You are not alone this week
The first Braxton Hicks tightening can be startling, and a new stretch mark can catch you off guard. Both are normal parts of a body doing exactly what it should at 21 weeks. Wherever your bump and your energy are right now, you are in good company.
21 weeks pregnant, common questions
What are Braxton Hicks contractions?
They are occasional, painless tightenings of the uterus, sometimes called practice contractions. They come and go irregularly and are not a sign of labor. If tightenings become regular, painful, or come with pressure or fluid, call your provider.
Can my baby taste what I eat at 21 weeks?
In a way, yes. Your baby swallows amniotic fluid, and flavors from your diet pass into it as the taste buds develop. It gives your baby an early introduction to the tastes of your everyday foods.
Is it too early to worry about counting kicks?
Formal kick counts belong to the third trimester. For now, simply get to know your baby’s usual pattern of active and quiet times. If you notice a clear drop in movement once it has become regular, call your provider to check in.
Can I do anything to prevent stretch marks?
Stretch marks are largely down to genetics and how quickly skin stretches, so there is no guaranteed prevention. Keeping skin well moisturized helps it stay comfortable and less itchy as it grows, and most marks fade to pale lines over time.
Sources
- American College of Obstetricians and Gynecologists (ACOG), second trimester care guidance.
- Mayo Clinic, Fetal development: the 2nd trimester.
- MedlinePlus, National Library of Medicine (NIH), Fetal development and prenatal care.
Medical disclaimer: This page is for information and education only and is not a substitute for professional medical advice. Every pregnancy is different. Always follow the guidance of your doctor, midwife, or qualified provider, and contact them with any concerns.