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18 weeks pregnant


Foetus at 18 weeks pregnantYour baby at 18 weeks

  • The pads on your baby's fingers and toes have fully formed whorls and spirals. Hopefully, she will not get finger printed in later life but this is where these unique identifiers begin.
  • Her hair and eyebrows are getting bushier and, while your baby is unlikely to be born with teeth, her jaws already hold little buds for milk teeth and behind them are tooth buds for her adult teeth.
  • Her lungs are gradually developing, with tiny 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. At 18 weeks she still won't be breathing because she is under water in her own amniotic bath, but she has a go. She both swallows and breathes out the amniotic fluid she's swimming in. It's this that gives her hiccups, which are tiny flutters first but later become seismic movements that make your belly shake.
  • She can 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 you, her mother and source of all nourishment, eat and drink.
  • She is moving around, crossing her legs, but also resting so there are quiet and busy times.
  • Her bones are ossifying, which means the flexible cartilage scaffolding is being filled in with calcium, which is hard. The bones in her legs are among the first to develop as are the tiny bones of her inner ear. There are already nerves that can hook up the vibrations in these inner ear bones to her brain, which means she can really and truly start to hear things.

Your body at 18 weeks pregnant

  • Breathing You may feel 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 get enough oxygen.
  • Back pain You're more prone to lower back pain now because your lower spine curves to stop you falling forward. The joints between your pelvic bones will be softer and looser now and so you feel less stable and tend to lean back to compensate. Try to walk about with a good posture, on flat shoes and when you sit down put a pillow behind your back to support it.
  • Feeling dizzy 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 slowly and if you feel faint sit down and put your head between your knees until it passes.
  • Skin 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.



Pregnancy Encyclopedia book coverIllustrations taken from The Pregnancy Encyclopedia, £25, published by DK.

Disclaimer: The information in the pregnancy calendar is for general information and is not intended as a substitute for the medical advice of your own doctor or antenatal team. Not all babies develop at the same time and in the same way, so this week-by-week guide may not always match your own experience. If you have any worries, consult your antenatal team or GP.

Last updated: 4 months ago