20 Weeks Pregnant: Development, Symptoms & Care

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The length convention changes to head-to-heel.

General education; your own maternity team guides your care. Sources checked 30 September 2026. No clinical review is claimed. Editorial standards.

Your baby at 20 weeks

About 25.6 cm (head to heel); roughly comparable to a banana. Sizes vary.

The skin has a protective waxy coating called vernix.
The jump in the guide’s length reflects a different measurement convention, not sudden overnight growth.

Earlier lengths describe head-to-bottom (crown–rump) size. From week 20 this guide uses head-to-heel, so the values cannot be compared as one continuous measurement series.

Development reference: NHS: week 20 development and symptoms.

Symptoms and body changes

Some early symptoms ease, while heartburn or constipation may continue.
Back or pelvic discomfort may occur as your body changes.
A symptom being common does not establish its cause; seek advice for pain, bleeding or concerns.

Your symptoms and bump may differ from someone else at the same week.
Discuss changes that worry you with your maternity team; you do not need to wait for the next appointment.

Check when to seek care if you are unsure about a symptom.

Your care plan this week

In NHS care the structural screening scan is offered at 18–21 weeks. Ask about your results and any follow-up; a scan cannot detect every condition.

Planning tip

Discuss any scan findings with your team rather than interpreting isolated measurements yourself.

A practical checklist

Discuss any scan findings with your team rather than interpreting isolated measurements yourself.
Write down questions or symptoms to discuss with your maternity team.
Check the date and purpose of your next appointment.

Activity and comfort

For an uncomplicated pregnancy, build activity gradually toward 150 minutes a week if your maternity team agrees. Keep a pace at which you can talk, avoid overheating and activities with fall or impact risk, and stop if you feel unwell. Avoid prolonged exercise flat on your back, particularly after 16 weeks.

Mental wellbeing

Tell your midwife or doctor if anxiety, low mood or loss of interest persists or affects daily life. Support and treatment are available. Do not stop prescribed mental-health medicine without advice. Seek immediate help if you may harm yourself or someone else.

Nutrition guidance

Fish can supply protein and omega-3 fats. US FDA/EPA guidance recommends 8–12 ounces a week from lower-mercury choices during pregnancy; follow local advice and any restrictions for fish you catch yourself.
Salmon, sardines and trout are examples of lower-mercury options. Tuna advice depends on the species and amount; use the linked fish chart rather than treating all fish alike.
If you do not eat fish, discuss suitable alternatives with your clinician. This guide does not prescribe a universal DHA dose or promise a particular IQ increase.

Needs and supplement recommendations vary by country and individual circumstances. NIH: pregnancy nutrients and supplements · NHS: pregnancy food safety · FDA/EPA: fish choices · NHS: severe pregnancy sickness.

Understanding movements

First movements are usually felt at 16–24 weeks. If none have been felt by 24 weeks, contact your midwife. Once you know the usual pattern, call maternity care immediately if it slows, stops or changes. Do not wait until the next day or use a home Doppler to reassure yourself.

Rest and sleep position

From 28 weeks, settle to sleep on either side, including for naps. If you wake on your back, turn onto your side. Pillows may help you feel comfortable; contact your clinician about persistent sleep problems.

When to get medical help

Get medical help immediately for trouble breathing, chest pain, fainting, severe or persistent abdominal pain, a severe headache or vision changes, fever of 38°C or higher, or marked swelling of the face or hands.
Seek urgent maternity advice for bleeding or spotting, leaking fluid, severe vomiting that prevents drinking, or one-sided painful leg swelling. Severe bleeding or collapse requires your local emergency service.
If you are less than 37 weeks pregnant and have regular contractions or tightenings, contact maternity care immediately. Do not wait for a contraction timer.
This is not an exhaustive list. If something feels wrong, contact your care team; tell them you are pregnant.

Read pregnancy warning signs and the CDC urgent warning signs.

Questions about week 20

How big is a baby at 20 weeks?

The NHS weekly guide gives an illustrative length of about 25.6 cm from head to heel. This is not a target for an individual baby. Your maternity team interprets growth in context.

What should I focus on at 20 weeks?

Discuss any scan findings with your team rather than interpreting isolated measurements yourself.

When should I contact maternity care?

Contact your team whenever you are worried, and immediately for urgent symptoms or a change in the usual movement pattern. Do not wait for the next appointment or a timer threshold. Use your local emergency service for severe symptoms or collapse.

Sources and editorial update

Guidance checked 30 September 2026. NHS weekly development summaries are illustrative; appointments and local recommendations may differ. Birth-term definitions use NIH / NICHD.

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Keep your questions together

Use the interactive guide to explore development, practical reminders and linked sources.

Explore week 20

Next: postpartum recovery · newborn care · safe infant sleep.