Week by Week Pregnancy: 21 Week Pregnant

At 21 weeks pregnant, your baby is around 26.7 cm long from head to toe and roughly the size of a carrot. Now that you are in the second half of pregnancy, your baby continues to grow rapidly while practising skills such as sucking and breathing movements that will be important after birth.

Your baby is increasingly active inside the womb and is beginning to develop periods of sleep and wakefulness. You may only recently have started noticing movements, or small kicks, turns and wriggles may now be becoming easier to recognise. Most people first feel their baby move between 16 and 24 weeks.

Week 21 can also be around the time of your 20-week screening scan. In England, this screening scan is usually offered between 18 and 21 weeks and examines your baby's physical development, growth and the placenta.

Week 21 highlight:
Your baby is now around 26.7 cm long from head to toe. They are moving, developing periods of sleep and wakefulness, hearing sounds from outside the womb, and continuing to develop their hair and eyebrows.

Contents

• What Does 21 Weeks Pregnant Mean?
• Baby Development at 21 Weeks
• How Big Is Your Baby at 21 Weeks?
• What Is Lanugo?
• Can Your Baby Hear at 21 Weeks?
• What Do Baby Movements Feel Like at 21 Weeks?
• Does Your Baby Have a Sleep Pattern at 21 Weeks?
• How Is Your Body Changing at 21 Weeks?
• What Can You See on an Ultrasound at 21 Weeks?
• What Are the Symptoms of Being 21 Weeks Pregnant?
• Frequently Asked Questions

21 Weeks Pregnant at a Glance

What Does 21 Weeks Pregnant Mean?

At 21 weeks pregnant, you are in the second trimester and have moved into the second half of pregnancy. Your baby is not simply getting bigger; several body systems and abilities continue to mature in preparation for life after birth.

Movements may become easier to identify during this stage. However, it can still be normal not to recognise your baby's movements clearly at 21 weeks. Most people first feel movement between 16 and 24 weeks, and in a first pregnancy this may happen after 20 weeks.

Your growing womb also makes your pregnancy bump increasingly noticeable. As your bump grows, your centre of gravity changes, which can affect the way you move and balance.

Baby Development at 21 Weeks

At 21 weeks, your baby is around 26.7 cm long from head to toe and roughly the size of a carrot. Your baby is continuing to grow and practise movements such as sucking and breathing movements.

At this stage, your baby weighs more than the placenta. The placenta continues to grow during pregnancy and plays an essential role in supplying your baby with oxygen and nutrients and helping remove waste products.

Your baby's body is covered with fine, soft hair known as lanugo. Hair and eyebrows are also continuing to develop. Much of the lanugo usually disappears before birth.

Your baby's hearing is developing too. Sounds from outside your body, including your voice, can reach your baby. Your baby is also moving around inside the womb and developing periods of sleep and wakefulness.

For a broader look at how your baby changes throughout pregnancy, read our Baby Development in the Womb guide.

How Big Is Your Baby at 21 Weeks?

At 21 weeks, your baby is approximately 26.7 cm long from head to toe, roughly the length of a carrot.

You may notice that this measurement looks much larger than the head-to-bottom measurement used in earlier weeks. From around this stage, pregnancy guides may begin describing your baby's full head-to-toe length rather than crown-to-rump length.

Why was your baby about 16.4 cm last week but 26.7 cm this week?
At 20 weeks, the NHS gives a measurement of approximately 16.4 cm from head to bottom. At 21 weeks, the measurement is approximately 26.7 cm from head to toe. The difference therefore does not mean your baby has grown by about 10 cm in a single week; the method of measurement has changed.

What Is Lanugo?

Lanugo is the fine, soft hair that covers your baby's body during pregnancy. At 21 weeks, this delicate layer is present across your baby's body and is a normal part of fetal development.

Lanugo is thought to help with temperature regulation and also helps the protective vernix remain on your baby's skin. Much of it usually disappears as pregnancy progresses, although some babies may still have small amounts when they are born.

Can Your Baby Hear at 21 Weeks?

Yes. At 21 weeks, your baby can hear sounds coming from outside the womb, including your voice. Their hearing continues to develop as pregnancy progresses.

You may choose to talk, read or sing to your baby. There is no need to treat this as a developmental exercise; it can simply be a natural way of connecting with your baby during pregnancy.

Your baby can hear you.
Sounds reach your baby differently inside the womb, but by this stage your voice and other sounds from the outside world can be heard.

What Do Baby Movements Feel Like at 21 Weeks?

At 21 weeks, baby movements may feel like fluttering, swirling, rolling, wriggling or small kicks. Movements that initially felt very subtle may gradually become easier to distinguish from digestive sensations.

Most people begin to feel their baby move between 16 and 24 weeks. If this is your first pregnancy, you may not notice movements until after 20 weeks.

There is no single number of movements that every baby should make each day. As pregnancy progresses, what matters is becoming familiar with your own baby's usual pattern of movement.

If you have not felt your baby move yet:
This does not necessarily mean that something is wrong. If you have not felt your baby move at all by 24 weeks, contact your midwife. They can check your baby's heartbeat and movements and arrange further assessment if needed.

Does Your Baby Have a Sleep Pattern at 21 Weeks?

At 21 weeks, your baby is developing periods of sleep and wakefulness. This means there may be times when your baby is more active and other periods when movements are quieter.

Your baby's active periods will not necessarily match your own daily routine. You may also notice movements more easily when you are resting or lying quietly because you are less distracted by your own activity.

There is no need to count a particular number of kicks at this stage. As movements become established, becoming familiar with your baby's individual pattern is more useful than aiming for a universal daily number.

How Is Your Body Changing at 21 Weeks?

At 21 weeks, your growing bump can change your centre of gravity, while pregnancy hormones can make your ligaments and joints more flexible. Together, these changes may affect your balance and the way you move.

Take care with activities where there is a significant risk of falling or being hit. If you fall during pregnancy, particularly if you hit your abdomen or subsequently experience pain, bleeding, leaking fluid or concerns about your baby's movements, contact your maternity service for advice.

Second-trimester symptoms such as backache, heartburn, constipation, leg cramps, headaches and increased vaginal discharge may also continue during Week 21.

Can You Have the 20-Week Screening Scan at 21 Weeks?

Yes. In England, the NHS 20-week screening scan is usually offered between 18 and 21 weeks of pregnancy. Your appointment may therefore take place during Week 21.

The scan looks carefully at your baby's physical development and screens for 11 physical conditions. Measurements are also taken to assess growth, and the placenta is checked.

The screening scan can provide important information about your baby's development, but it cannot detect every possible health condition. Screening is a choice, and you can decide whether you wish to have it.

In Part 2:
We'll look more closely at the 21-week ultrasound, your baby's size, the 20-week screening scan, common pregnancy symptoms, abdominal and pelvic pain, vaginal discharge, nutrition, exercise and sleep.

What Can You See on an Ultrasound at 21 Weeks?

At 21 weeks, an ultrasound can show your baby's head, face, spine, heart, arms, legs and several internal structures in considerable detail. You may also see your baby moving their arms and legs, turning or changing position during the scan.

If you have not yet had your 20-week screening scan, your appointment may take place during Week 21. In England, this screening scan is usually offered between 18 and 21 weeks of pregnancy.

During the scan, measurements are taken to assess your baby's growth and the placenta is checked. Your baby's sex may sometimes be visible if they are in a suitable position, although finding out the sex is not the medical purpose of the scan and local hospital policies can vary.

How Big Is Your Baby at 21 Weeks?

At 21 weeks, your baby is around 26.7 cm long from head to toe and roughly the size of a carrot. Your baby continues to grow and gain weight during the second half of pregnancy.

You may notice a substantial difference between this measurement and the figures used in earlier weeks. This is largely because measurements around this stage may switch from head-to-bottom length to full head-to-toe length.

Do Baby Movements Increase at 21 Weeks?

At 21 weeks, your baby's movements may be becoming easier to recognise. Sensations that initially felt like gentle fluttering or bubbling may gradually become more noticeable as turns, wriggles, nudges or small kicks.

There is considerable variation in when movements are first noticed and how strongly they are felt. The position of the placenta can also affect how easily you notice your baby's movements. An anterior placenta, where the placenta is attached to the front wall of the womb, may cushion some movements.

There is no universal number of movements that you should feel each day. As your pregnancy progresses, the important thing is to become familiar with your own baby's usual pattern of movement.

If you have not felt your baby move yet:
Most people first feel their baby move between 16 and 24 weeks. If you have not felt any movement by 24 weeks, contact your midwife. They can check your baby's heartbeat and movements and arrange further assessment if necessary.

What Are the Symptoms of Being 21 Weeks Pregnant?

At 21 weeks, your growing womb and continuing hormonal changes can cause a range of second-trimester symptoms. Every pregnancy is different, so you may experience several symptoms, only a few, or very mild changes.

Common symptoms can include backache, stretching sensations around your abdomen, leg cramps, heartburn, indigestion, bloating, constipation, headaches and dizziness. Mild swelling of your feet and ankles that develops gradually, particularly later in the day, can also occur during pregnancy.

You may also notice increased vaginal discharge and changes in skin pigmentation.

Is Abdominal Pain Normal at 21 Weeks Pregnant?

Mild, short-lived abdominal discomfort or stretching sensations can occur at 21 weeks. Stretching of the ligaments supporting your growing womb, constipation and trapped wind are among the common causes of abdominal discomfort during pregnancy.

Ligament pain may feel like a sharp pain or pulling sensation on one or both sides of your lower abdomen, particularly when you stand up, turn suddenly, cough or change position.

Seek medical advice if the pain is severe, does not settle or is getting worse. You should also contact your maternity service if abdominal pain occurs with vaginal bleeding, regular cramps or tightenings, lower back pain, unusual vaginal discharge, leaking fluid, a high temperature or pain when passing urine.

Can You Have Pelvic Pain at 21 Weeks Pregnant?

Pregnancy-related pelvic girdle pain can occur at 21 weeks. Pain may be felt around the pubic area, hips, lower back, groin or pelvis and may become worse with certain movements.

Walking, climbing stairs, standing on one leg, turning over in bed and getting in or out of a car can be uncomfortable. If pelvic pain is making it difficult to move around or carry out everyday activities, speak to your midwife or GP. Assessment and physiotherapy can help manage pregnancy-related pelvic girdle pain.

Is Vaginal Discharge Normal at 21 Weeks Pregnant?

It is normal to have more vaginal discharge during pregnancy. Healthy pregnancy discharge is usually thin, clear or milky white and should not have an unpleasant smell.

Contact your midwife or GP if your discharge smells unpleasant, becomes green or yellow, or is accompanied by itching, soreness or pain when passing urine, as these symptoms can indicate an infection.

White discharge that looks similar to cottage cheese and occurs with itching or irritation may be caused by thrush. If you think you have thrush during pregnancy, ask your midwife, GP or pharmacist about treatment that is suitable for pregnancy.

If you notice watery fluid from your vagina:
If you experience a continuous trickle or sudden gush of watery fluid, do not assume that it is ordinary pregnancy discharge. Contact your maternity service for advice.

Is Swelling Normal at 21 Weeks Pregnant?

Mild swelling of the feet and ankles that develops gradually can occur during pregnancy, particularly later in the day. Sudden or rapidly increasing swelling needs to be considered differently.

Seek medical advice immediately if you develop a sudden increase in swelling of your face, hands or feet, particularly if it occurs with a severe headache, blurred vision or flashing lights, severe pain below your ribs, vomiting or feeling very unwell. These can be symptoms of pre-eclampsia.

It is important to recognise the symptoms of pre-eclampsia from this stage of pregnancy.
Pre-eclampsia usually develops from around 20 weeks. Blood pressure and urine protein checks during antenatal appointments help healthcare professionals look for signs of the condition.

What Should You Eat at 21 Weeks Pregnant?

Continue to eat a varied and balanced diet at 21 weeks. Fruit and vegetables, higher-fibre carbohydrate foods, pregnancy-safe sources of protein, and dairy foods or suitable alternatives can all form part of your everyday diet.

You do not need to “eat for two”. Rather than doubling your portions, focus on a balanced diet and a variety of nutritious foods.

Vitamin D remains important during pregnancy. Follow pregnancy food-safety advice and avoid supplements containing vitamin A in the form of retinol, which can be harmful to your baby in high amounts. Check that any vitamin, supplement or herbal product is suitable for pregnancy before taking it.

Can You Exercise at 21 Weeks Pregnant?

If your pregnancy is progressing normally and you have not been advised otherwise by a healthcare professional, staying active is generally encouraged. Walking, swimming and other pregnancy-appropriate activities can be good options.

Do not exhaust yourself during exercise. As a practical guide, you should still be able to hold a conversation while exercising. If you become too breathless to talk comfortably, reduce the intensity.

Your centre of gravity changes as your bump grows, so take particular care with activities that carry a risk of falling or being hit.

How Should You Sleep at 21 Weeks Pregnant?

Your growing bump, baby movements, heartburn, leg cramps or backache may begin to make comfortable sleep more difficult. Sleeping on your side and using pillows between your knees or underneath your bump may help you find a more comfortable position.

The NHS specifically advises going to sleep on your side from 28 weeks of pregnancy. You can sleep on either your left or right side.

If you wake up on your back, there is no need to panic. Simply turn onto your side before going back to sleep.

In Part 3:
We'll cover what can be normal at 21 weeks, when to contact your midwife or maternity service, bleeding, warning signs of pre-eclampsia, baby movements, the 20-week screening scan, common myths, your Week 21 checklist and frequently asked questions.

What Is Normal at 21 Weeks Pregnant?

At 21 weeks, a growing pregnancy bump, increasingly noticeable baby movements, mild stretching discomfort, backache and digestive changes can all be normal. Pregnancy symptoms vary considerably, so you may experience several of these changes or very few.

Heartburn, indigestion, constipation, bloating, leg cramps, headaches, dizziness and increased vaginal discharge can occur. Mild swelling of the feet and ankles that develops gradually, particularly later in the day, can also happen during pregnancy.

It can still be normal not to have clearly felt your baby move at 21 weeks. Most people first notice movements between 16 and 24 weeks, and in a first pregnancy this may happen after 20 weeks.

How Can You Support a Healthy Pregnancy at 21 Weeks?

During the second trimester, continue to focus on a varied and balanced diet, regular fluids, pregnancy-appropriate physical activity and attending your antenatal appointments.

• Eat a varied and balanced diet.
• Drink fluids regularly throughout the day.
• Continue following pregnancy food-safety advice.
• Avoid alcohol and smoking.
• Do not stop prescribed medicines without speaking to a healthcare professional.
• Check before taking medicines, vitamins, supplements or herbal remedies.
• Stay physically active if appropriate for your pregnancy.
• Continue pelvic floor exercises.
• Look after your teeth and gums.
• Attend your antenatal appointments and any screening you choose to have.

When Should You Contact Your Midwife or Maternity Service at 21 Weeks?

Many new symptoms can occur during pregnancy, but some changes should be assessed by a healthcare professional. Seek advice if a symptom is severe, persistent, getting worse or occurs alongside other concerning symptoms.

Contact your midwife, GP or maternity service if you experience:

• vaginal bleeding or spotting;
• severe, persistent or worsening abdominal or pelvic pain;
• regular cramps or tightenings;
• possible leaking of fluid from your vagina;
• unpleasant-smelling, green or yellow vaginal discharge;
• vaginal itching or soreness;
• pain or burning when passing urine;
• a high temperature;
• severe or repeated dizziness or fainting;
• vomiting that prevents you from keeping food or fluids down;
• significant pain, swelling, tenderness or warmth in one leg;
• sudden or rapidly increasing swelling of your face, hands or feet.

Some symptoms require urgent medical assessment.
Seek urgent medical help if you have heavy vaginal bleeding, severe abdominal pain, significant difficulty breathing, fainting, loss of consciousness or feel seriously unwell.

Is Bleeding Normal at 21 Weeks Pregnant?

Bleeding during pregnancy does not always mean there is a serious problem, but it should be assessed. The amount and colour of the bleeding, how long it lasts and whether you have symptoms such as pain, cramping or dizziness are all relevant.

If you experience vaginal bleeding or spotting at 21 weeks, contact your maternity service for advice. Seek urgent medical attention if the bleeding is heavy or accompanied by severe pain, fainting, significant dizziness or feeling seriously unwell.

What Are the Signs of Pre-eclampsia at 21 Weeks Pregnant?

Pre-eclampsia is a pregnancy complication that usually develops from around 20 weeks and requires medical assessment. Some people initially have no obvious symptoms, which is one reason blood pressure and urine protein are checked during antenatal appointments.

Seek medical advice immediately if you develop symptoms such as:

• a sudden increase in swelling of your face, hands or feet;
• a severe headache;
• problems with vision, such as blurring or flashing lights;
• severe pain just below your ribs;
• vomiting;
• feeling very unwell.

Sudden swelling is different from mild, gradual pregnancy swelling.
Gradual swelling of the feet and ankles can occur during pregnancy. A sudden increase in swelling, particularly when accompanied by headache, visual changes or pain below the ribs, requires prompt medical advice.

When Is Abdominal or Pelvic Pain a Concern at 21 Weeks?

Mild abdominal discomfort can occur as your womb grows and the supporting ligaments stretch. Constipation and trapped wind can also cause abdominal discomfort during pregnancy.

Pregnancy-related pelvic girdle pain may be worse when walking, climbing stairs, standing on one leg, turning over in bed or getting in and out of a car. Speak to your midwife or GP if pelvic pain is affecting your mobility or everyday activities.

Seek medical advice if abdominal or pelvic pain is severe, persistent or worsening, or occurs with bleeding, regular cramps or tightenings, lower back pain, unusual vaginal discharge, leaking fluid, a high temperature or pain when passing urine.

Is It Normal Not to Feel Your Baby Move at 21 Weeks?

Yes. It can still be normal not to have clearly felt your baby move at 21 weeks. Most people first feel movements between 16 and 24 weeks. If this is your first pregnancy, you may not notice them until after 20 weeks.

The first movements may feel like fluttering, bubbling, swirling, rolling or gentle kicks rather than obvious strong movements.

If you have not felt your baby move at all by 24 weeks, contact your midwife. They can check your baby's heartbeat and movements and arrange further assessment if necessary.

Once you regularly feel your baby moving, become familiar with their usual pattern.
If your baby is moving less than usual, you cannot feel them moving any more or their usual pattern changes, contact your midwife or maternity unit immediately. Do not wait until the next day.

What Should You Know About the 20-Week Screening Scan at 21 Weeks?

Your 20-week screening scan may take place during Week 21. In England, the scan is usually offered between 18 and 21 weeks and examines your baby's physical development.

The scan screens for 11 physical conditions, takes measurements to assess your baby's growth and checks the placenta. It can provide important information about your baby's development, but it cannot detect every possible condition.

If your baby's position makes it difficult for the sonographer to obtain all the required views, you may be offered another appointment to complete the examination.

Common Myths About Being 21 Weeks Pregnant

Your 21-Week Pregnancy Checklist

• Check the dates of your upcoming antenatal appointments.
• Keep track of your 20-week screening scan if you have not yet had it.
• Continue eating a varied and balanced diet.
• Drink fluids regularly throughout the day.
• Follow pregnancy food-safety guidance.
• Check that medicines and supplements are suitable for pregnancy.
• Stay physically active if appropriate for your pregnancy.
• Continue your pelvic floor exercises.
• If you are feeling movements, gradually become familiar with your baby's usual pattern.
• Remember to contact your midwife if you have not felt any movement by 24 weeks.
• Do not ignore sudden swelling, severe headaches or changes in vision.
• Seek medical advice for bleeding, severe pain or other concerning symptoms.

Key Takeaway

At 21 weeks pregnant, your baby is around 26.7 cm long from head to toe and roughly the size of a carrot. Your baby continues to grow, move and hear sounds, while their periods of sleep and wakefulness are developing. Movements may be becoming easier to recognise, and your 20-week screening scan may also take place around this stage.

Frequently Asked Questions

How big is a baby at 21 weeks?

At 21 weeks, your baby is around 26.7 cm long from head to toe and roughly the size of a carrot. Individual measurements can vary.

How many months is 21 weeks pregnant?

21 weeks pregnant is commonly described as being around 5 months pregnant. However, because calendar months vary in length, healthcare professionals use weeks rather than months to date pregnancy more accurately.

Which trimester is 21 weeks pregnant?

At 21 weeks pregnant, you are in the second trimester.

What do baby movements feel like at 21 weeks?

Movements may feel like fluttering, bubbling, swirling, rolling, wriggling or small kicks. They generally become easier to recognise as pregnancy progresses.

Is it normal not to feel movement at 21 weeks?

Yes. Most people first feel their baby move between 16 and 24 weeks. In a first pregnancy, this may happen after 20 weeks. Contact your midwife if you have not felt any movement by 24 weeks.

Can a baby hear at 21 weeks?

Yes. Your baby can hear sounds from outside the womb, including your voice. Their hearing continues to develop throughout pregnancy.

Does a baby sleep at 21 weeks?

Yes. Your baby is developing periods of sleep and wakefulness, so there may be times when they are more active and other times when they are quieter.

Can you have the 20-week screening scan at 21 weeks?

Yes. In England, the NHS 20-week screening scan is usually offered between 18 and 21 weeks, so your appointment may take place during Week 21.

Should you have a visible bump at 21 weeks?

Your pregnancy bump is likely to be increasingly noticeable by 21 weeks, but there is considerable normal variation in the size and shape of pregnancy bumps.

Can pre-eclampsia develop at 21 weeks?

Yes. Pre-eclampsia usually develops from around 20 weeks. Symptoms such as sudden swelling, a severe headache, visual disturbances or severe pain below the ribs require prompt medical advice.

What happens at 22 weeks pregnant?

At 22 weeks, your baby continues to grow and develop. Movements may become easier to recognise as you progress through the second trimester.

Related Guides

• 19 Weeks Pregnant
• 20 Weeks Pregnant
• Pregnancy Week Calculator
• Due Date Calculator
• Baby Development in the Womb

References

• NHS – 21 Weeks Pregnant
• NHS – Week-by-Week Guide to Pregnancy
• NHS – Your Baby's Movements
• NHS – 20-week Screening Scan
• NHS – Pre-eclampsia
• NHS – Pelvic Pain in Pregnancy
• NHS – Stomach Pain in Pregnancy
• NHS – Vaginal Discharge in Pregnancy
• NHS – Vaginal Bleeding in Pregnancy
• NHS – Swollen Ankles, Feet and Fingers in Pregnancy
• NHS – Exercise in Pregnancy
• NICE – Antenatal Care

Medical information: This guide provides general information and is not a substitute for personalised medical advice, diagnosis or treatment. If you have concerns about your pregnancy or symptoms, contact your midwife, GP or maternity service.