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18 weeks pregnant

By week 18 you’re almost at the halfway point of your pregnancy (hooray!) and it’s only a matter of days and weeks until you'll see your baby again at your next scan.

By Mumsnet HQ | Last updated Jul 15, 2021

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Your baby at 18 weeks

Your baby is getting ready for her next close-up at the 20-week scan. Here’s what she’s up to this week…

  • The pads on your baby's fingers and toes are already fully formed with a pattern of whorls and spirals unique to her – even if you’re having identical twins, they’ll still have their own different fingerprints. So, if your tiny foetus has a career ahead of her as a master criminal, this is where these unique identifiers that could one day be her downfall begin.

  • Hair and eyebrows are getting bushier and, behind the milk teeth that have already formed in her jaws, are tiny tooth buds for her adult teeth.

  • Her lungs are developing apace, with air sacs, called alveoli, appearing. These sacs provide a huge area for the lungs to take in oxygen and get rid of carbon dioxide once your baby is born and is breathing by herself.

  • At 18 weeks she still won't be breathing properly because she is underwater in her own amniotic bath, but she has a jolly good go in preparation – she both swallows and breathes out the amniotic fluid she's swimming in. It's this that gives her hiccups, which feel like tiny flutters first but, later in pregnancy, become seismic movements that can shake your whole bump, and may even wake you up at night.

  • As well as breathing, she can also swallow around a litre of fluid a day and this includes her urine that she pees into the amniotic fluid. Some research shows there's a 24-hour pattern to when your baby swallows fluid and produces urine that may be related to what is eaten and drunk by the mother.

  • She is moving around, somersaulting and crossing and uncrossing her legs. But there are also now periods when she is resting so you’ll find there are quiet and busy times. If you are feeling your baby’s movements already you might start to notice a pattern as to when these quiet and busy times occur.

  • Her bones are ossifying, which means the flexible cartilage scaffolding is continuing to be filled in with calcium, which makes them hard. The bones in her legs and the tiny bones of her inner ear are among the first to develop.

Your 18 week baby bump

My bump comes and goes. It's my third though so I have no muscles left to hold it in…

It's probably safe to say things are coming along by now, with a nice noticeable roundness that you're keeping a keen eye on. Try taking a bump picture week to week for better perspective on those changes that you might not notice in the mirror.

Bumps come in all shapes and sizes and vary hugely from woman to woman, so don't worry if yours is still on the smaller side. The strength of your abdominal muscles and whether it's your first of second pregnancy will play a part in dictating size – just remember, your midwife will be keeping a close eye on your measurements and will be able to put your mind at rest.

Around this time, the average woman gains about half to a kilo of weight per week, so don't be surprised if you find yourself with a little extra padding in other areas, too.

What size is the baby at 18 weeks?

At week 18 your baby is 14cm long – about the size of a bell pepper – and weighs 190g.

18 weeks pregnant symptoms

As things stretch and expand a little more day by day, you’ll experience symptoms that are caused by these new changes to your body.

Feeling dizzy

This is increasingly common because the veins in your pelvis and legs hold more blood than usual and if you get up in a hurry your blood may not get distributed quickly enough up to your head. Get up from sitting or lying positions slowly and if you feel faint sit down and put your head between your knees until it passes.

Skin changes

You may find your skin is dry and itchy, especially on your arms and legs. Using moisturiser will stop the flaking and itching.

Because you are hotter than usual from all the dilated blood vessels in your skin you will find you sweat more and may get heat rashes under your arms of in your groin. Take regular baths or showers and wear cotton to stay comfortable.

How is your body changing at 18 weeks pregnant?

Your womb is still stretching and growing and is now the size of a canteloupe.

You may feel like you're breathing faster as well as more deeply when you breathe in and out. Blame the progesterone but don't feel anxious if you suddenly become aware of your breathing. You and your baby will definitely get enough oxygen.

As you gain weight, your lower spine curves to stop you falling forward, which can put you at greater risk of backache.

Hormones have made the joints between your pelvic bones softer and looser so you feel less stable and tend to lean back to compensate. Try to maintain good posture at all times and avoid waddling. Wearing flat shoes and putting a pillow in the small of your back to support it when you sit down will both help.

Things to think about during week 18 of pregnancy

The anomaly scan

Your anomaly scan, also known as your 20-week scan, might be any time from now to week 20 itself and there are some things it’s worth considering before you go.

  • Think about whether or not you want to know the sex of your baby. The hospital may have a policy of not saying anyway but if you definitely don’t want to know it’s worth making that clear right at the start just in case the sonographer gives away any identifying information.

  • Bear in mind that, exciting though this scan is, it’s called an anomaly scan for a reason – they are looking for potential ‘anomalies’ so while the vast majority of women come away with a lovely photo and nothing more, there’s a small possibility that they may pick up an issue at this scan. It’s just worth remembering if you were planning to take a younger sibling perhaps.

What Mumsnetters say

"I am 18 weeks gone and have not had any strong symptoms. I feel fine, I do have a bump and the other noticeable thing happening is larger boobs and change in nipple colour."

"Currently sporting a rather oversized bump and am totally shattered, but apart from that really hardly any symptoms at all."

"So long as the heartbeat is strong then any lack of symptoms really isn't an issue… You are just lucky."

"I am 18 weeks with my first baby and STILL absolutely shattered and then not sleeping well at night."

"I'll be 18 weeks tomorrow and everyone I meet is shocked at how much I'm showing. They ask if I'm sure there is only one and if I have my dates right!"

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