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18 Weeks Pregnant: Week-by-Week Guide

18 Weeks Pregnant: Week-by-Week Guide

At 18 weeks pregnant, you’re in your second trimester and fifth month. So much is going on with you and your baby. Check out this week-by-week guide to find out what’s in store for both of you in week 18 of pregnancy.

  • 18 weeks pregnant is which trimester? Second trimester
  • How many weeks of pregnancy are left? 22 weeks
  • 18 weeks pregnant is how many months?  You're in your fifth month.

With week 17 of your pregnancy complete, you’re on week 18. Enjoy it, as week 19 is on the horizon! 

One of the most exciting things about pregnancy is how many changes you’ll experience with your little one over the span of just seven days! Here are some tips and tricks to keep on top of all that’s happening.

Your baby at 18 weeks pregnant:

What’s happening in there

  • 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 your 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 feeling backaches and muscle pains. The hormone relaxin is to blame. It relaxes your ligaments and loosens joints, which can change your posture. Coupled with the added weight, your back may begin to hurt more than usual.
  • When you're 18 weeks pregnant, your baby's bones start changing from a soft substance to a strong, hard structure. This process, called ossification, usually begins in the collarbones and legs. Take a prenatal vitamin with brain-nourishing docosahexaenoic acid (DHA) and eat calcium-rich foods, which will help those bones become strong.

How big is your baby at 18 weeks pregnant?

18 Weeks Pregnant

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 changing quickly. As your baby grows, you will too, and there are certain pregnancy symptoms you may experience at this time.

7 common week 18 pregnancy symptoms

  1. You may get cramps in your legs, but staying hydrated can help.
  2. There's a chance that you may get nose bleeds during this time.
  3. You may notice varicose veins forming, so prop up your legs and avoid tight shoes.
  4. You could have trouble sleeping or disturbed sleep—it's like your body's preparing you for your first years of parenthood.
  5. You may have an achy back. Hormones, your growing belly, and posture changes are the culprits.
  6. Water retention, called edema, may cause your feet and hands to swell. Staying hydrated, limiting salt intake, and keeping cool can help. Contact your doctor with any concerns or if you experience severe or rapid swelling.
  7. You may feel like you have a tiny soccer player inside you as your baby’s kicks get stronger.  

3 tips for week 17 for a healthy and safe pregnancy

Being 18 weeks pregnant is an important time for you and your baby. Here are some tips on how to adjust to this new stage to keep you and your baby safe.

  • Ironing out the details: Make sure you’re boosting your iron intake. If you’re not getting adequate iron, it can affect you and your baby.
  • Strong bones: 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.
  • Zzzzzz: You should be sleeping on your side by week 18.

Week 18 pregnancy checklist

Knowing what to do week-by-week can help you feel prepared and alleviate stress. Add these new items to your to-do list this week. You’ve got this, mama!

Week 18 Pregnancy To-Do’s Complete
lan a nice date night—you both deserve it Plan a nice date night—you both deserve it is complete
Update your exercise routine to account for your current shape Update your exercise routine to account for your current shape is complete
Write the invite list for your baby shower Write the invite list for your baby shower is complete

Learn more about your pregnancy, including pregnancy planning and pregnancy nutrition, to feel prepared to continue this magical adventure. You’re armed with the facts and know what to do, so now you can take time to connect with the little one growing inside you.

With week 17 in the rearview mirror and week 18 going strong, look to the future and what's coming up in week 19!

Join Enfamil Family Beginnings

It’s your 18th week of pregnancy, and you and your baby are experiencing exciting changes every day. Prepare for your new arrival with help from Enfamil Family Beginnings. It’s the perfect resource for new and expecting moms. Save on Enfamil products, track your bump and baby’s growth, and get helpful articles each week relevant to your journey. Join now for up to $400 in free gifts.