you're 21 weeks pregnant.
last revised · baby is about 26.7 cm (10.5") · 360 g (12.7 oz)
At 21 weeks pregnant, your baby is about 26.7 cm and 360 g — Now measured head-to-heel, your baby is the length of a carrot.
about the size of a…
Now measured head-to-heel, your baby is the length of a carrot. They can swallow amniotic fluid and even hiccup.
this week's highlights
- Head-to-heel measurement starts
- Hiccups begin
- Eyebrows and eyelashes visible
- Strong reflexes
how your baby looks
Long and lean. Eyebrows and eyelashes are clear, lips are taking shape, and the eyes can move under closed eyelids.
body in focus
- head
- Eyebrows and eyelashes are visible.
- body
- Hiccups happen as breathing reflex develops.
- hands
- Fingers grasp the umbilical cord and play with it.
- feet
- Toes wiggle and kicks press against the uterine wall.
what's happening in your body
You may feel little rhythmic jumps — those are baby hiccups. Belly is rounding out and may itch as skin stretches.
symptoms at 21 weeks
- Round ligament pain
- Sharp or pulling twinges at the sides of your bump as the ligaments supporting your uterus stretch. Moving slowly when you stand or turn over usually eases it.
- Increased appetite
- Your baby is growing fast and your body asks for more fuel. Aim for steady, balanced meals rather than large ones, which can worsen heartburn later.
- Mild backache
- Your centre of gravity is shifting forward, which loads the lower back. Gentle stretching and supportive shoes make a real difference.
- Vivid dreams
- Hormones and lighter sleep make dreams more intense and memorable in mid-pregnancy. It is common and nothing to worry about.
- Nasal congestion
- Extra blood flow swells the lining of your nose, a condition called pregnancy rhinitis. Saline sprays and a humidifier at night can help.
- Faster-growing nails and hair
- Pregnancy hormones speed up growth cycles, so nails and hair may feel thicker. This usually settles again after the birth.
gentle tips
- Apply belly oil or balm twice daily to soothe stretching skin.
- Eat protein at every meal — your baby's tissues need it.
- Stand up slowly to prevent dizziness.
- Save energy: nap when possible.
- Plan a baby moon if travel is comfortable for you.
your week 21 checklist
- Book your whooping cough (pertussis) vaccination — it is recommended between weeks 16 and 32 to protect your newborn.
- Start researching antenatal classes in your area; popular ones fill up early.
- Review your maternity leave entitlement and note key notification deadlines for your employer.
- Begin a simple list of newborn essentials so purchases can be spread over the coming months.
what to expect next
Many people feel a noticeable bump grow each week from now. Sleep gets a bit harder as the belly changes positions.
common questions at week 21
How big is the baby at 21 weeks?
At 21 weeks, the baby measures about 26.7 cm and weighs approximately 360 g (26.7 cm (10.5") · 360 g (12.7 oz)).
What is developing at 21 weeks?
Long and lean. Eyebrows and eyelashes are visible. Key milestones this week include: Head-to-heel measurement starts; Hiccups begin; Eyebrows and eyelashes visible; Strong reflexes.
What symptoms are common at 21 weeks pregnant?
You may feel little rhythmic jumps — those are baby hiccups. Belly is rounding out and may itch as skin stretches.
What should I do at 21 weeks pregnant?
Many people feel a noticeable bump grow each week from now. Apply belly oil or balm twice daily to soothe stretching skin. Eat protein at every meal — your baby's tissues need it. Stand up slowly to prevent dizziness.
Why do I feel fewer kicks with an anterior placenta?
When the placenta sits at the front of the uterus, it acts like a cushion between the baby and your belly wall, so movements can feel muffled and appear later. You will still learn your baby's own pattern over the coming weeks. If you ever feel that movements have reduced once a pattern is established, call your midwife or doctor.
Is it safe to sleep on my back at 21 weeks?
From around the second half of pregnancy, side sleeping is recommended because lying flat on your back lets the uterus press on major blood vessels. Going to sleep on your side, ideally the left, is the safest habit to build now. If you wake up on your back, do not panic — simply roll onto your side and settle back to sleep.
Can I still fly at 21 weeks pregnant?
For most uncomplicated pregnancies, flying in the second trimester is considered the most comfortable window. Check your airline's policy, keep well hydrated, and walk or flex your ankles regularly to support circulation. Discuss any travel plans with your midwife or doctor first if you have complications or a higher-risk pregnancy.
helpful tools
- Belly Timeline
Document your bump week by week with photos.
- Kick Counter
Track fetal movement — kicks usually begin around week 18–22.
- Milestones
Week-by-week milestones tied to your due date.
Medically aligned with guidance from WHO, NHS and ACOG. How we write.