Week 21 Pregnancy

Second Trimester

Last reviewed: July 2026

21 weeks pregnant at a glance

You are in the second trimester.
Your baby is roughly the size of a carrot.
Routine midwife appointment to check growth and well-being.
Every pregnancy is different, so don't worry if your experience varies slightly.

You are 21 weeks pregnant and in your second trimester. Your baby is about the size of a carrot. This week's key development: Finding a Rhythm. NHS note: Routine midwife appointment to check growth and well-being.

The Anomaly Scan Window

Between 18 and 21 weeks, you'll be offered the anomaly scan. It looks closely at your baby's bones, heart, brain, spinal cord, face, kidneys and abdomen.

This page is for general pregnancy planning and date guidance only. It is not medical advice, diagnosis, or treatment. Pregnancy dates are estimates and can change after a scan or advice from your midwife, GP, or maternity team. Always speak to a qualified healthcare professional if you have symptoms, concerns, or questions about your pregnancy.

Week 20

Week 22

Baby's Development

Your baby is about the size of a carrot.

Finding a Rhythm — Your baby is establishing sleep and wake cycles, and you may start to notice patterns — active in the evenings, quiet in the mornings, or vice versa. Eyebrows and eyelashes are now visible, and the lips are becoming more defined.

Carrot

Approx. 26.7cm

Your Symptoms

Varicose veins
Stretch marks
Increased appetite

Every pregnancy is different. You may experience all, some, or none of these symptoms — and that's completely normal. If anything concerns you, speak to your midwife.

NHS Appointments

Routine midwife appointment to check growth and well-being.

Practical Advice for Week 21

Nutrition

Continue vitamin D daily.
Eat regular, balanced meals to manage your increased appetite.
Include foods rich in vitamin K (broccoli, kale) for blood clotting.
Stay well hydrated — 2 litres of water per day is a good target.

Exercise

Walking remains one of the best forms of exercise throughout pregnancy.
Swimming or aqua aerobics — perfect for supporting your growing body.
If varicose veins are appearing, gentle movement helps circulation.
Avoid prolonged standing — take regular breaks if your job requires it.

Wellbeing

You may notice your baby has sleep and wake patterns — enjoy getting to know them.
Stretch marks are common — they affect most pregnant women and fade significantly.
Your appetite may increase — eat nutritious foods but don't restrict yourself.
If varicose veins are bothering you, support tights can help.

Preparation

Routine midwife check — growth and wellbeing assessment.
Start assembling a shortlist of baby names.
If you're planning a nursery, now is a good time to start (while you have energy).
Consider writing a baby shower guest list if friends are planning one.

Tip of the Week

Keep active with walking or swimming to help with circulation and leg aches.

Frequently Asked Questions for Week 21

How many months is 21 weeks pregnant?

At 21 weeks pregnant, you are roughly 4 months pregnant. Remember that pregnancy is typically measured in weeks rather than months for clinical accuracy.

What size is the baby at 21 weeks?

At 21 weeks, your baby is roughly the size of a carrot (about 26.7cm). Your baby is establishing sleep and wake cycles, and you may start to notice patterns

What are the common symptoms at 21 weeks pregnant?

Common symptoms at this stage include varicose veins, stretch marks, increased appetite. Remember that every pregnancy is unique, and it's normal to experience different symptoms.

Is 21 weeks in the second trimester?

Yes, 21 weeks falls within the second trimester.

Are there any NHS appointments at 21 weeks?

Routine midwife appointment to check growth and well-being.