pregnancy-week-by-week

21 weeks pregnant

You and your baby's development

What's happening in week 21 of your pregnancy

21 weeks into your pregnancy and you are over half way there!

At a glance

  • Your baby is starting to gain weight
  • Now is a good time to book your antenatal classes
  • Talk to your baby to help them recognise your voice when they're born
21 weeks pregnant

How big is my baby at 21 weeks?

At week 21 the average baby will measure around 26.7cm long and weigh around 360g but this will vary from baby to baby. They’re starting to gain weight now, and laying down some fat, which will give them that adorable chubby newborn appearance the moment you first set eyes on them!

Their eyebrows and eyelids have now formed and it’s possible for them to blink. Amazingly your baby will now already have taste buds and can taste a variety of different flavours depending on what you’re eating and what’s entering the Amniotic fluid. They will be swallowing this fluid now as they practice their technique.

Their skin is also looking a bit different now, as it will have gained a coating of a white, waxy substance known as Vernix caseosa. This protects their body from the effects of bobbing around in amniotic fluid for so long! You will probably see areas of it still on your baby when they are born.

Facts to know about your baby in week 21

  • From the second trimester, babies pee in the uterus, then they drink it, then they pee again, then they drink it

  • Your baby starts making its first poo, called meconium, around now, it won't poop until after birth

  • Every baby develops a fine moustache while in the womb. This fine hair later spreads all over their body

  • Your baby now weighs more than your placenta, about 360g

You at 21 weeks pregnant

By now your midwife or GP will have given you a MAT B1 certificate (at 20 weeks), which you need to give to your employers straight away – the certificate enables you to claim Statutory Maternity Pay and confirms your pregnancy and expected due date for your employer's records.

You can start your maternity leave from 11 weeks before the expected week of your baby's birth – you need to let your employer know when you plan to start it by the end of the 15th week before your due date. 

Statutory Maternity Leave is 52 weeks long, and is classed as ‘Ordinary Maternity Leave’ for the first 26 weeks, and then 'Additional Maternity Leave’ for the final 26 weeks. You don't have to take all 52 weeks off, and under recently introduced rules, your partner might be able to share some of your maternity leave if you want to return to work sooner.

With Statutory Maternity Pay you get 90% of your average weekly earnings (before tax) for the first 6 weeks. Then £145.18 or 90% of your average weekly earnings (whichever is lower) for the next 33 weeks.

If you aren't eligible for SMP you may be able to claim Maternity Allowance. It can be claimed as soon as you’re 26 weeks pregnant and the payment can start from 11 weeks before your baby’s due date.  How much you’ll get depends on your eligibility, but you could receive either: £145.18 a week or 90% of your average weekly earnings (whichever is less) for up to 39 weeks – or £27 a week for up to 14 weeks.

If you’re not sure whether you qualify for Maternity Allowance use the Gov.uk website’s Maternity Entitlement Calculator to check whether you’re eligible.

You might also be thinking of booking your antenatal classes around now, if you have decided to attend them. Your midwife will have information about free local groups, and you can get details about NCT classes near to you online.

Lots of women make friends for life at their antenatal groups, so if it is your first baby, it is an excellent way of making lots of mum-to-be pals, and sharing experiences (and niggles and moans!) And of course, lots of little same age playmates for your bubba in the future! Classes can get booked up really quickly, so get your name down as soon as you can.

Apart from the socialising, you'll also learn about pain relief in labour, breathing techniques and your options in delivery at your classes – and if you go to a NHS one attached to your hospital, probably a tour of the delivery suite, too. Have a look at our pages on antenatal classes for more info.

Facts to know about you in week 21

  • It's sometimes suggested (but not proven) baby's heart rate is under 140 beats minute it's a boy, and if faster it's a girl
  • You’re likely to gain 1-5lbs in the first trimester and on average 0.8-1lb a week in trimesters 2 and 3
  • Avoid sitting with your knees higher than your hips (like on a soft sofa or in a car), and lying on your back
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What to think about in week 21

Passing the half way point in your pregnancy is a milestone and a great feeling. Looking through endless lists of baby names while watching TV and scanning through the credits for inspiration is probably one of your favourite pass times now. With a world of choice out there, how do you decide on the perfect name for your little one?

You may well have discovered the sex of your baby at your 20 week scan, but have you decided to share the news with your nearest and dearest? There are some fun ways you can share the news. With so much news shared on social media today, you can have some while letting everyone know whether you are expecting a boy or girl. 

For example, you could take a picture of your bump while wearing blue or pink. One way is you can post it on social media, which is a great way of involving family and friends who are living far away, but there are lots of creative ways to share the sex of your baby

You probably find yourself absent-mindedly stroking your bump and chatting away to your baby quite a lot anyway, but did you know that they can hear you, and talking to them now will help them to recognise your voice once they are born? Some mums-to-be like to sit and read story books or sing nursery rhymes to their bumps, or play them certain music – you might even find that there are tunes which make your baby mega active!

Talking and reading to your unborn baby is something that dads can get involved in to, and is a lovely way to bond before birth.

Signs and symptoms at 21 weeks pregnant

Skin changes

Skin like everything else can be affected by your pregnancy, and there are a number of changes you may notice. You may notice more spots than usual and some can appear like acne. These are hormone related and should disappear once your baby is born. Some women can suffer with itchy or sensitive skin particularly around the bump where your skin is stretching. Stretch marks are a common skin change pregnant women notice and although they should fade somewhat after your baby is born. Other skin changes include the visibility of broken veins on the skin, changes in skin colour including brown patches of hyper-pigmentation or the brown line down your bump (Linea negra).

Bloating and wind

An uncomfortable and sometimes embarrassing symptom of pregnancy, bloating and wind is caused by increased pressure on the oesophagus from your growing uterus. Your hormones also cause your digestion tract to slow down which causes the build-up of wind and bloating. Unfortunately, there’s not much you can do about it because you don’t have the same control over your muscles in pregnancy. If you are suffering particularly badly from bloating and wind you can talk to your GP or midwife about what treatments you may be able to take to help to ease the symptoms. Some mums-to-be say ginger or chamomile tea and eating more garlic helps ease the symptoms. Also try eating small meals throughout the day instead of three large meals.


Watch our videos below:

Video 1: How often should my unborn baby move? (NHS content)

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Video 2: Getting ready for your baby's arrival

Baby Names

Search for a name, sibling names, middle names - or use our random name finder for some creative fun!

At a glance

  • Your baby is starting to gain weight
  • Now is a good time to book your antenatal classes
  • Talk to your baby to help them recognise your voice when they're born

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