18 Weeks Pregnant: Week-by-Week Guide
18 Weeks Pregnant

18 Weeks Pregnant: Week-by-Week Guide

Congratulations! You are 18 weeks pregnant. At this stage of your journey, new developments are beginning to unfold. Explore our week-by-week guide to find out what’s in store for your baby and your body in week 18 of pregnancy.

At 18 weeks pregnant:

  • Your baby is the size of a cucumber.
  • You’re in your fifth month.
  • The countdown continues: you’ve got 22 weeks to go!

What happens during the 18th week of pregnancy?

  • Your baby’s hardwired those little nerves are now active and growing, ready for baby to explore the wonders of the outside world. To keep them protected, they’re covered with a substance called myelin that helps those impulses shoot from nerve cell to nerve cell through the body.
  • 100 billion — that’s how many neurons have grown in your baby’s brain in these first four months!
  • Shhhhh, someone’s listening with the development of those nerve endings and the formation of the bone in your baby’s inner ear, your baby can hear your heartbeat, the movement of blood through the umbilical cord and your tummy’s rumbles and gurgles.

What should I be feeling at 18 weeks pregnant?

  • You might start feeling movements, with your baby not just twisting and turning, but even yawning.
  • With all the growth of your uterus and its precious contents, you may start to be getting backaches and muscle pains. The hormone relaxin is to blame. It relaxes your ligaments and loosens joints, but this, in turn, can change your posture, which, along with the added weight, can cause back pain.
  • When you're 18 weeks pregnant, your baby's bones are starting to change from a soft substance to a strong, hard structure. This process, called ossification, usually begins in the collarbones and legs. Take your prenatal vitamin with brain-nourishing docosahexaenoic acid (DHA) and eat calcium-rich foods, which will help those bones to become strong, plus it aids in blood clotting, nerve transmission, and clotting.

18 Weeks Pregnant Facts

How big is your baby? Check out the chart below to find out!

Baby Size at 18 Weeks
Baby Weight 7 ounces
Baby Length 5.5 inches
Baby Size Comparable to a cucumber or artichoke

Week 18 Pregnancy Symptoms

During week 18 of pregnancy, your body is adjusting to the new life it's supporting. As your baby changes, you will too, and there are certain pregnancy symptoms you may experience at this time. Keep these week 18 pregnancy symptoms on your radar:

  • You may get cramps in your legs. Be sure to stay hydrated as it will help reduce these.
  • There's a chance that you may get nose bleeds during this time.
  • Spidery varicose veins will be appearing, so prop up your legs, get exercise, and avoid tight shoes.
  • You may find you're having trouble sleeping or disturbed sleep - it's like your body's prepping you for your first years of parenthood.


Being 18 weeks pregnant is an important time for you and your baby. Get advice on how to adjust to this new stage.

  • Make sure you’re boosting your iron intake. If you’re not getting adequate iron it can affect you and your baby.
  • Eat calcium-rich foods. That calcium will help your baby’s bones become firm; it also aids in muscle contraction, blood clotting, and nerve transmission.
  • If you’re not already doing it, you should be sleeping on your side by week 18.

Week 18 Checklist: Plan Your Pregnancy

Be prepared. Explore our pregnancy checklist below and add these items to your to-do list this week.

To-Do Complete
Plan a nice date night you both deserve it!
Update your exercise routine to account for your current shape.
Write the invite list for your baby shower

Get insight to what you’re feeling as your baby moves around or read ahead about week 19.