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Highlights this week

Mid-pregnancy ultrasound

You'll have an ultrasound at 18 to 22 weeks to check on your baby's health and monitor medical complications.

Sign up for childbirth class

These classes tell you what to expect during labor and teach techniques to help you relax and cope with the pain.

Eat moderately and often

Eating a healthy snack every three hours will keep your blood sugar level so you're less likely to be starving at dinnertime.

18 weeks is how many months?

You're in your fifth month!

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Baby development at 18 weeks

Ears in place

Your baby's ears are now in their final position, although they're still standing out from his head a bit.

Lungs branching out

In the lungs, the smallest tubes (bronchioles) start to develop at the tips of the branches. At the end of these tiny tubes, respiratory sacs begin to appear. By the time your baby is born, these sacs will become enmeshed with tiny blood vessels and allow oxygenated blood to circulate to all of the body's organs and tissues.

Girl and boy parts

If you're having a girl, her uterus and fallopian tubes are formed and in place. If you're having a boy, his genitals are noticeable now, but he may hide them from you during an ultrasound.

baby with ears in place
Your baby at 18 weeks Tap the plus for more details
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Your baby is about the size of a bell pepper

bell pepper
5 ½
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head to bottom
6 ¾
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Pregnancy symptoms during week 18

Ravenous hunger

Hungry? An increase in appetite – and specific food cravings – are pretty common about now.


Your cardiovascular system is undergoing dramatic changes, and during this trimester your blood pressure will probably be lower than usual. Don't spring up too fast from a lying or sitting position, or you might feel a little dizzy.

Don't see your symptom?
Wondering about a symptom you have? Find it on our pregnancy symptoms page.

baby in womb at 18 weeks
Your body at 18 weeks Tap the plus for more details

Pregnancy checklist at 18 weeks pregnant

Think about your maternity leave

It's not too early to look into what you need to do to prepare for maternity leave. Find out what benefits you're eligible for and fill out all the paperwork you can in advance.

Prepare your older children

If you already have a child, the new baby may rock their world even more than yours. Fortunately, there are things you can do to help set the stage for a new brother or sister.

Learn the best way to buckle up

It's extra important to wear your seat belt during pregnancy – and to buckle up the right way. Secure the lap portion low under your belly and snug across your hip bones, and position the shoulder harness snugly between your breasts and off to the side of your belly.

18 weeks pregnant bellies

This week's video


BabyCenter's editorial team is committed to providing the most helpful and trustworthy pregnancy and parenting information in the world. When creating and updating content, we rely on credible sources: respected health organizations, professional groups of doctors and other experts, and published studies in peer-reviewed journals. We believe you should always know the source of the information you're seeing. Learn more about our editorial and medical review policies.

ACOG. 2016. FAQ119. Exercise during pregnancy. American College of Obstetricians and Gynecologists. http://www.acog.org/Patients/FAQs/Exercise-During-Pregnancy [Accessed May 2019]

ACOG. 2015. FAQ156. Prenatal development: How your baby grows during pregnancy. American College of Obstetricians and Gynecologists. http://www.acog.org/Patients/FAQs/Prenatal-Development-How-Your-Baby-Grows-During-Pregnancy#one [Accessed May 2019]

Mayo Clinic. 2015. Fetal development: The 2nd trimester. http://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/fetal-development/art-20046151 [Accessed May 2019]

MedlinePlus (ADAM). 2015a. Fetal development. https://www.nlm.nih.gov/medlineplus/ency/article/002398.htm [Accessed May 2019]

MedlinePlus (ADAM). 2015b. Kegel exercises—self-care. https://medlineplus.gov/ency/patientinstructions/000141.htm [Accessed May 2019]

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Kate Marple is a writer and editor who specializes in health, pregnancy, and parenting content. She's passionate about translating complicated medical information into helpful pregnancy and parenting advice that's easy to understand. She lives in San Francisco with her family.
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