pregnancy week 21
21 weeks pregnant.
Now measured head-to-heel, your baby is the length of a carrot. They can swallow amniotic fluid and even hiccup.
Updated 29 July 2026 · Sources: NHS and ACOG
Your baby this week
Long and lean. Eyebrows and eyelashes are clear, lips are taking shape, and the eyes can move under closed eyelids.
- Head-to-heel measurement starts
- Hiccups begin
- Eyebrows and eyelashes visible
- Strong reflexes
What may be changing in your body
You may feel little rhythmic jumps — those are baby hiccups. Belly is rounding out and may itch as skin stretches.
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.
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.
A useful partner move this week
Take over one physical chore this week that involves bending or lifting, such as the laundry or the heavy shopping. Ask which class or hospital tour she wants to book, then put the dates in both of your calendars yourself.
What comes next
Many people feel a noticeable bump grow each week from now. Sleep gets a bit harder as the belly changes positions.
Common questions
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.
How many months is 21 weeks pregnant?
Pregnancy months do not divide evenly into weeks, so clinicians date pregnancy in weeks. At 21 weeks, you are in trimester two.