Our Baby Journey21 weeks pregnant
21 weeks pregnant is about 5 months. It falls in the fifth month of pregnancy. You are in week 21 of 40, in the second trimester. Here is what is happening with your baby and your body this week.
Your baby is about the size of a carrot.
Length: about 26.7 cm (10.5 in) from crown to heel · Weight: about 360 g (12.7 oz)
Your baby at 21 weeks
Movements are getting stronger and more coordinated. The baby has regular sleep and wake cycles.
Your baby's digestive system is getting regular practice. By now your baby swallows amniotic fluid every day, and the intestines absorb some of the water and sugar from it. What is left behind starts to build up as meconium, the dark, sticky substance that usually becomes your baby's first poop after birth.
Inside the bones, bone marrow is starting to take over the job of making blood cells, a task that the liver and spleen have handled until now. Your baby's arms and legs are now in proportion with the rest of the body, and the limbs have enough muscle to produce kicks and jabs you can feel clearly.
Your baby's taste buds are also maturing. Because the flavors of what you eat can pass into the amniotic fluid, your baby may already be getting a first introduction to the foods your family enjoys.
Your body at 21 weeks
Swelling in your feet and ankles may begin. Stretch marks may appear.
Your uterus now reaches roughly to the level of your belly button or a little above, and your growing belly may start to change how you move and balance. Increased blood volume and the pressure of the uterus on the veins in your pelvis slow blood returning from your legs, which is why mild swelling and visible veins can appear. Hormones that loosen your ligaments for birth can also make your hips, lower back, and pelvis feel achy. Many people find their energy is still relatively good this week, which makes it a practical time to stay active with walking or swimming.
Your belly at week 21
In month 5 (weeks 18–22) your bump is usually clearly visible. At about 20 weeks the top of the uterus reaches your belly button. From around 20 weeks, your fundal height (the distance in centimeters from your pubic bone to the top of the uterus) roughly matches the number of weeks you are pregnant, give or take about 2 cm.
Belly size and shape vary a lot depending on your build, whether this is your first pregnancy, your baby's position and the amount of amniotic fluid. At checkups your doctor or midwife may measure your fundal height to track your baby's growth, and may arrange an ultrasound if the measurement is quite different from what they expect.
Symptoms at 21 weeks pregnant
- Stronger, more frequent kicks and rolls
- Mild swelling in the feet and ankles by the end of the day
- Varicose or more visible veins in the legs
- Pink or reddish stretch marks on the belly, hips, or breasts
- Increased vaginal discharge that is thin and milky
- Lower back or round ligament aches
Checkups around week 21
If you had your mid-pregnancy anatomy ultrasound at around 18 to 20 weeks, this may be when you get or discuss the results. Some people have this scan a little later, around 20 to 22 weeks, and timing varies by country and clinic. If anything needed a closer look, your provider may book a follow-up scan.
Tips for week 21
- Put your feet up when you can to reduce swelling.
- Avoid standing for long periods.
- Report sudden swelling of the face or hands to your provider.
Common symptoms in the second trimester
The second trimester runs from week 14 to week 27. Nausea often eases, energy returns, your bump starts to show, and you will begin to feel your baby move. Not everyone has every symptom, and it is normal for symptoms to come and go. Common ones include:
- A growing bump and weight gain
- First baby movements, usually felt between weeks 16 and 25
- Round ligament pain (sharp pains low in the belly or groin)
- Heartburn and indigestion
- Back ache
- A blocked nose or nosebleeds
- Leg cramps
- Skin changes such as a dark line on the belly or darker patches on the face
Read the full second trimester guide.
When to call your doctor or midwife
Contact your healthcare provider or maternity unit straight away, or get emergency care, if you have:
- Vaginal bleeding
- Severe or persistent abdominal pain or cramping
- A severe headache, blurred vision, or sudden swelling of your face, hands or feet
- A fever of 38°C (100.4°F) or higher
- Fluid leaking from your vagina
- Severe vomiting where you cannot keep fluids down
- Your baby moving less than usual or a change in their pattern of movements (later in pregnancy)
- Regular contractions before 37 weeks
- Pain or burning when you urinate
- Feeling very low, anxious, or having thoughts of harming yourself
Have a question about week 21?
Ask our AI pregnancy assistant about symptoms, nutrition, scans or anything else on your mind this week.
Frequently asked questions
How big is my baby at 21 weeks pregnant?
At 21 weeks pregnant, your baby is about the size of a carrot. That is about 26.7 cm (10.5 in) from crown to heel, weighing about 360 g (12.7 oz).
How big is my belly at week 21 of pregnancy?
In month 5 (weeks 18–22) your bump is usually clearly visible. At about 20 weeks the top of the uterus reaches your belly button. From around 20 weeks, your fundal height (the distance in centimeters from your pubic bone to the top of the uterus) roughly matches the number of weeks you are pregnant, give or take about 2 cm. Bump size, shape and when you start to show vary a lot from person to person.
How much should my baby be moving at 21 weeks?
At 21 weeks, movements are often felt but can still be irregular, and many people notice them more when resting or lying down. There is no set number of movements you should count at this stage. If you are a first-time parent or your placenta is at the front of the uterus, movements may feel softer. Later in pregnancy, regular movement becomes an important sign of wellbeing, so if you are ever worried, contact your doctor or midwife.
Can I prevent stretch marks at 21 weeks?
Stretch marks are largely influenced by genetics, skin type, and how quickly your skin stretches, so they cannot always be prevented. Moisturizing creams and oils can ease the itching and dryness that often come with a growing belly, even if they do not stop stretch marks forming. Gaining weight gradually and in line with your provider's advice may help. Most stretch marks fade to a paler, silvery color in the months after birth.
Is it safe to exercise at 21 weeks pregnant?
For most people with an uncomplicated pregnancy, regular moderate exercise such as walking, swimming, stationary cycling, or prenatal yoga is encouraged. Avoid contact sports, activities with a high risk of falling, and lying flat on your back for long periods. You should be able to hold a conversation while exercising. Stop and contact your doctor or midwife if you have bleeding, dizziness, chest pain, fluid leaking, or painful contractions.
What trimester is 21 weeks pregnant?
Week 21 is in the second trimester, which covers weeks 14 to 27.
How many months is 21 weeks pregnant?
21 weeks pregnant is about 5 months. It falls in the fifth month of pregnancy. The fifth month covers weeks 18 to 22. Pregnancy is about 40 weeks, or roughly 9 months, counted from the first day of your last period.
This page is general educational information and is not a substitute for advice from your doctor or midwife. Every pregnancy is different, and baby sizes are approximate averages. Last updated 2026-11-07. See our medical disclaimer.