Pregnancy Week 31

Discover your baby's developments now that you're 31 weeks pregnant, and learn to practice labor techniques for a more relaxed and easier delivery experience.

Week by week baby size image. Week by week baby size image.

How big is baby?

Your baby is about as long as a bunch of leeks, and she will now gain as much as a half pound per week until she's born.

Baby's Length: 16.18in.
Baby's Weight: 3.31lb.
Fetus at Week 31 What the baby looks like at week 31 of fetal development. Med ART Studios Explore More

Baby's Development

Your baby is gaining more weight than height at this point. Because she's too big to stretch out, she's now forced into the fetal position, which she'll stay in until birth. This week also boasts some exciting reproductive developments. Having a boy? His testicles are moving through the groin on their way into the scrotum. And if you've got a girl in there, her clitoris is already relatively formed.

Baby Week 31

At about 16 inches and weighing about 3 pounds your baby is about the size of a small melon.Your baby is starting to move around more, flip upside down, rotate and even turn its head from side-to-side.Your baby's brain is now more fully developed, with speech and language centers in the process of development. Complex neurological connections and learning will continue throughout the pregnancy and long after birth.
Week by week baby ultrasound image. Week by week baby ultrasound image. American Institute of Ultrasound in Medicine -

Week 31 Ultrasound

This image gives a close-up view of the lower end of your unborn baby's spine. You can see the spinal cord protected by the bright white bones of the spine.

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Watch Baby's Growth

What Week 31 of Your Pregnancy is Really Like

Mom's changing body

You may be noticing more hip and lower-back pain. What gives? Pregnancy hormones are relaxing the ligaments and tendons throughout your pelvic area so that the bones can spread to make room for delivery. Your expanding uterus may also be putting some pressure on the sciatic nerve, which runs from your lower back to your buttock and hip area and down the back of each leg, triggering chronic tingling or numbness along its path — a condition called sciatica. But it's usually not serious, it won't affect the baby and it will likely become less intense as he shifts around in there.

Weekly Tip

Strangers on the subway reach out and touch your belly. A woman at the grocery store wrongly warns you against having sex ("It will make you go into early labor!"). Your neighbor asks if you're planning on circumcising your little boy (and clearly has strong opinions on the subject). Sound familiar? Now that your belly is front and center, chances are it'll attract a lot of attention and unwanted pregnancy advice. Just laugh it off and try not to let the comments worry or sway you. Your opinion and your doctor's are the only ones that matter; simply deem the rest amusing distractions.

Pregnancy Confidential Podcast

What Happens in the Delivery Room, Stays in the Delivery Room

At Week 31, you're probably finding your mind ever-­wandering back to the elephant in your third trimester room: how you're actually gonna birth this sucker. While the physical realities of having a baby are surely present on your mind, you're also bound to be curious about what goes on around you when you're giving it the ol' heave-­ho. Who do you let in the room with you? Will you really do something as horrific as poop in front of everybody? And will you even care? This week's podcast lets you in on the deepest darkest secrets of the delivery room, so you know just what to expect when you're done expecting.

This Week's To-Do List


Growing Big: Weeks 31 to 34 of Pregnancy

Your baby now weighs about three pounds, roughly the size of a melon. Get the scoop on how much more she'll grow before she's born--and what new developments she's making right now.

10 Reasons to Call the Doctor Now

Is your child sick enough for a late-night call to the pediatrician? If you're really worried about your child, it's always better to call -- pediatricians expect to be awakened in the middle of the night. In fact, doctors say that many parents don't recognize some of the most serious medical situations. Here are the top 10 symptoms pediatricians want you to call about right away.

Birth Day: Your Baby's First 24 Hours of Life

While you've probably mapped out what your post-delivery hospital stay will entail, you may not realize that your baby will be twice as busy as you'll be. Just five minutes after he arrives, he is poked, pricked, measured, tested, cleaned, and swaddled. Delivery procedures are different in every hospital, but here's what's likely to happen in the whirlwind that's your baby's first day.

Week 31 Ultrasound: What It Would Look Like

Find out what new things you might see on an ultrasound when you're 31 weeks pregnant. Plus, learn about the major reproductive developments at this stage.

Building a Mommy Support System

When dealing with the ups and downs of parenthood, who better to turn to than other new moms?

Pregnancy Confidential Podcast Week 31: Delivery Room FYIs

Find out what's going on in week 31 of your pregnancy on this podcast episode of Pregnancy Confidential.