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Week 18 of Pregnancy

Written by Amina Hatia RM
Medically reviewed by Marley Hall BA RM Diphe
January 25, 2022

You are now four and half months pregnant – so almost halfway there.  As your pregnancy progresses, you’ll find that most of the growth is now focused on your bump.  At this stage, it’ll affect you mainly in clothing you are wearing and your changing shape – although this varies from person to person, so don’t fall into the trap of comparing bumps!  You may be wondering why your bump is becoming so prominent if your baby is the size of a sweet potato – surely that can’t be causing a bump to appear?!

Well, you are right – your baby is only part of the story – your uterus is now the size of a small melon because it is housing not only your baby, but the placenta, the amniotic fluid around baby and all that extra blood flow too. 

When you are looking or feeling your bump, it’s a combination of all of the above – not just your baby. Your fundus – which is the top of your uterus at this stage in your pregnancy, will be around where your belly button is and goes down to your pubic bone, just below your bikini line. Have a feel of your bump – the fundus will feel like a firm ridge.  As your pregnancy progresses, you’ll find that your fundus will feel higher and higher.

As your bump grows you may notice a line of pigmentation going down your stomach – this is common and very normal, so don’t worry at all.  It’s sometimes referred to as the linea nigra and is just a concentration of normal skin pigmentation and in most cases will disappear after your baby has arrived.

How big is my baby?

At 18 weeks, your baby is measuring around the size of a sweet potato or an artichoke!  Head to bottom, your baby is measuring around 14 cms and now weighing a lovely 190 grams.

What happens in week 18 of pregnancy?

Your baby is continuing to do amazing things and mature inside you. This week, baby’s lungs are continuing to develop with the main branching tubes starting to develop smaller tubes at their tips, which will eventually become air sacs.

They are also learning how to sleep and nap too now – with the internal clock that regulates sleeping developing around 18 weeks.

Similarly, your baby’s nervous system is also developing in intricate details, with the production of a fat and protein called Myelin that protects nerve cells in the nervous system such as the brain and the spinal cord. 

Week 18 pregnancy symptoms

Indigestion – if you have pregnant family members or friends, you’ve probably already heard from them about the havoc pregnancy can play with your digestive system. And they aren’t alone – indigestion for example, is a very common pregnancy complaint, caused by the pregnancy hormones that relax muscles in your body.  This has an impact on your digestive system too – by relaxing it, your digestion can become slow and sluggish. 

Similarly, your growing baby also has an impact – by pushing your stomach up and all squished, which causes the stomach acids to come up and causing you to suffer heartburn.

Whilst hormones and a growing baby can’t be avoided in pregnancy, you don’t have to just suffer with indigestion. There is lots you can do, and your midwife and GP can also help and advice.  

If you are struggling with indigestion in pregnancy, try:

  • Try having smaller meals throughout the day to help your sluggish system work better
  • Avoiding trigger foods like rich, spicy or fatty foods.
  • Make sure you sit upright when eating (ruling out crashing out on the sofa with a takeaway) and stay sitting upright after eating. 
  • If indigestion strikes most at night – check what you are eating in the evenings and try cutting out evening snack.

Week  18 pregnancy tips

  • How comfy is your sleep these days – your changing body, your new shape and those pregnancy side affects such as feeling hot can all have an impact on your sleep too.  Try investing in a good pregnancy pillow to support your bump and make for a better night’s sleep.
  • Have you had started thinking about your plans for work after baby has arrived? – now is a good time to start thinking about when and how you would like to maternity leave, what you are entitled to and what your rights are. Your employer can advise and support you, but lots of really helpful advice available in this link too: