Fetal Development

Fetal Development answers your questions about the changes that take place in the womb during pregnancy. Learn about each of the three trimesters and the developmental milestones that occur in each.

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Very little is known about what or how fetuses see. This study shows their vision capabilities are more advanced than previously thought.

By Alia Hoyt

A new device tested on fetal lambs could change care for human preemies, immersing them in a "biobag" with lab-made amniotic fluid, keeping them underwater for weeks.

By Patrick J. Kiger

New analysis also shows that preemies born between 22 and 24 weeks of pregnancy are less likely to develop health issues.

By Laurie L. Dove

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To make sure your little bundle of joy arrives healthy, it's a good plan to have regular monitoring tests during your pregnancy. See what's in store for the next nine months.

By Michael Franco

Thirty-nine weeks down, only one or two more to go! Here's what's going on with you and baby during these final days of pregnancy.

By Stefani Newman

So, your due date came and went, and you're still lugging around that passenger. How can someone so little be so stubborn?

By Julia Layton

That baby is technically ready to go, and it could happen any minute now. So what are you experiencing at 37 weeks, and what's happening in that enormous belly of yours?

By Julia Layton

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You've got two short, waddling weeks left, give or take, before your baby greets the world, and the excitement (and anxiety) might be keeping you up at night. So what are you experiencing in week 38?

By Julia Layton

Though you're only six weeks from your official due date, you might feel like you're looking at the longest six weeks of your life. What can you expect in week 34 of your pregnancy?

By Rebecca Fairley Raney

You're in the third trimester now, and your baby bump has swollen to a baby boulder! If you haven't decorated your nursery or picked out a baby name, it's time to get cracking. We've got a few more hints for moms at 28 weeks.

By Alia Hoyt

While you might be experiencing less-than-pleasant things such as constipation and swelling in your hands and feet, take a look at the exciting developments happening with your baby during your 29th week of pregnancy.

By Stefani Newman

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Welcome to the big 3-0 -- your 30th week of pregnancy, that is. You've got about 10 weeks to go until your baby arrives, so let's take a look at what's happening during the homestretch of your pregnancy.

By Alison Cooper

Fasten your seatbelts, ladies: While you may carry to 42 weeks (or, Lord help you, beyond), "full term" is just six weeks off. That means in a month and a half, you've got the green light to give birth to that tiny person you're carrying around.

By Julia Layton

Feel like you just might burst? Hang in there: At week 32, you've got as little as five weeks until you're full-term, and just eight until you enter "overdue." You're nearing the end. And the beginning. And that baby is huge.

By Julia Layton

What's the mind-body experience you'll have at 33 weeks? Every kick helps you count down to the day you'll deliver your little acrobat. The nursery's ready, but there are still some things to think about and some important preparations to make.

By Alia Hoyt

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By week 26, your discomfort, anxiety and excitement are probably growing at similar rates. Baby is roughly, astonishingly, just 14 weeks off. So what should you prepare for now?

By Julia Layton

If, up to now, you've barely been showing, week 27 could be your entry into the "obviously pregnant" zone. You're getting so close -- what should you expect during this transition between the second and third trimesters?

By Julia Layton

There are no breaks in the action when you're pregnant. It's week after week of miracles and heartburn. Week 18 is no exception. What's going on inside you?

By Julia Layton

By 19 weeks, you're probably starting to truly feel pregnant. It'll get worse before it gets better, but don't worry: As soon as you feel those tiny kicks, you'll forget it all.

By Julia Layton

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You're rounding third on month four, and with just 25 waist-expanding weeks until the moment you've been waiting for, you might be feeling better than you have in some time. What should you expect in week 15?

By Julia Layton

The day comes when you take a drive without a pit stop and get through a day without getting sick. Hopefully first-trimester symptoms are starting to ease up in week 12, leaving plenty of room for a new set of sensory experiences.

By Julia Layton

In week 13, pregnancy is probably starting to be a whole lot more fun. Lots of women find the middle months to be the easiest, with fewer unpleasant symptoms and new reasons to be excited. So what should you expect in this banner week of pregnancy?

By Julia Layton

By Week 10, if you were to look closely at your baby, you'd notice she doesn't look like a tadpole anymore. Her embryonic tail, at the bottom of the spinal cord, has disappeared and her rapidly developing spinal nerves have become visible. What else can you see?

By Laurie L. Dove

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Hopefully your morning sickness has started to subside and your energy level has increased. You might even be starting to see that "pregnancy glow." But you will be experiencing some new changes ahead. Let's take a look.

By Laurie L. Dove

Like "one-week pregnant," two weeks along exists only in retrospect. That doesn't mean the second week of pregnancy doesn't matter, though. There's no baby yet, but there's a lot of preparation going on.

By Julia Layton