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Week 27 of Pregnancy

Written by Amina Hatia RM
Medically reviewed by Marley Hall BA RM Diphe
February 14, 2022

You may be relieved or surprised to know that at 27 weeks you are now in the last week of your second trimester!

It’s a good time to reflect back on all the amazing changes that have happened with you and your baby in the last few months and how far you have both come. This last part of the journey of pregnancy is a reminder of just how amazing and special the new developments and changes have been too.

How big is my baby at 27 weeks?

At 27 weeks your baby is growing and now is around the size of a head of a cauliflower! By the end of this week your baby will be measuring just over 36 centimetres tall, whilst weighing a decent 870 grams or more.

What happens in week 27 of pregnancy?

As you near the end of your second trimester, all of your baby’s essential organs continue to mature and develop ready for life after birth. Your baby’s lungs in particular have continued to develop ready for that first big breath after birth – and this week, should start producing surfactant which is a combination of proteins and fats that support your baby and keep their lungs inflated so they can breathe unassisted.

At 27 weeks the surfactant is just starting to really develop, so there isn’t enough yet for the baby’s lungs to work unassisted – but over the next few months will continue to increase in time for your baby’s birth. And remember, until your baby is born, all of their oxygen and nutrients are being supplied via that amazing placenta you grew.

Another development this week is how your baby looks – though still little, your baby is really starting to fill out – thanks to the layer of insulating fat they have developed this week which is just under their skin. Your baby’s skin now looks a lot smoother and baby soft, thanks to this extra layer of fat.

Week 27 pregnancy symptoms


Is a common pregnancy related condition that is caused by a lack of red blood cells called haemoglobin.

The job of haemoglobin is to collect oxygen from your lungs and then carry it around your body. However, in order to create haemoglobin, your body needs iron, so when there isn’t enough iron stored in the body, your haemoglobin levels will drop and lead to anaemia.

The reason why it occurs in pregnancy is because your baby, who needs a lot of iron while they are growing inside you, will take the iron from you – leading to your own stores of iron being affected. This won’t affect every pregnancy – if your iron stores are at a good level before you become pregnant and you have an iron rich diet, it’s unlikely you will be affected.

Because anaemia is common in pregnancy, your haemoglobin levels are checked at your first booking appointment, and then again at the start of your third trimester.  However, your midwife will also carry out blood tests if you experience any of the common symptoms of anaemia such as:

  • Tiredness
  • Breathlessness
  • Heart palpitations
  • Weakness
  • Headache
  • Dizziness

 Try not to worry if you are told you have anaemia – there are lots of options for treatment and your midwife will discuss these with you.

Anaemia in pregnancy can affect your muscle and gut function, leave you feeling very tired, whilst also increasing your risk of having a smaller baby or your needing a blood transfusion after birth due to heavy bleeding – so it’s best to checked if you are worried and ensure you get the right treatment for you.

You will usually be advised to start a course of iron tablets, with a repeat blood test after a few weeks to see if this has helped improve your haemoglobin (HB) level.  How many you take a day will depend on what your HB levels are like, but they are best taken with food – ideally something that contains vitamin c as that will help the iron to be absorbed better. If the tablets don’t help, or you are in the final few weeks of your pregnancy and your haemoglobin levels are low your midwife will discuss other options with you such as intravenous iron (iron via an IV) directly into your bloodstream.

Week 27 pregnancy tips

  • It’s a great time to get more iron rich food into your diet, even if your iron levels are ok, so start adding some extra red meat, fish and poultry into your diet. Lentils, cereals, and leafy green vegetables such as kale are also a good option. Have a read of the NHS advice on iron-rich foods and foods to avoid here:
  • Do you have your 28-week midwife appointment arranged and booked for next week? If you don’t contact your midwife to find out when and where you can be seen. Keep a track of when you should be seen by following this schedule:
  • Have you started to think about your hospital bag? What to pack, what you might need to buy, how much of it all you need? It will of course depend on where you are having your baby and how – but planning ahead will help you feel prepared. We cover this and lots more practical, real life advice in our antenatal classes run by our team of NHS experienced midwives.