Pregnancy Week 16

You've reached the end of your fourth month! Find out how your baby is developing in week 16 as well as how to deal with stretch marks, changes in your feet, and more.

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

How big is baby?

Your baby is now the size of an avocado—and she can make a fist and even suck her thumb.

Baby's Length: 4.57in.
Baby's Weight: 3.53oz.
Fetus at Week 16 What the baby looks like at week 16 of fetal development. Med ART Studios Explore More

Baby's Development

Your baby's delicate skeleton continues to harden from rubbery cartilage to bone. Even so, his bones will remain somewhat flexible for an easier trip through the birth canal. The umbilical cord has fully matured with one vein and two arteries that are protected by Wharton's jelly (a thick substance that makes the cord slippery so it can move freely around your baby). By the way, if you're having a girl, hundreds of thousands of eggs are forming in her ovaries this week -- your future grandchildren!

Baby Week 16

The uterus continues to expand and move forward to accommodate fetal growth. This may make your belly more prominent.Approximately 4 inches in length and weighing 4 ounces, the developing fetus is about the size of a lemon.The chest expands and contracts, drawing amniotic fluid into the lungs to prepare the lungs for breathing.
Week by week baby ultrasound image. Week by week baby ultrasound image. American Institute of Ultrasound in Medicine -

Week 16 Ultrasound

In this closeup view of Baby's profile, you can see how his facial features are becoming more defined. Notice that the sonographer has measured the length of his nasal bone. This specialized measurement may be useful in screening for some genetic abnormalities.

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Watch Baby's Growth

What Week 16 of Your Pregnancy is Really Like

Mom's changing body

Got butterflies in your belly? It could very well be your baby kicking! Most moms-to-be experience this majorpregnancy milestone between their 16th and 20th weeks, but don't expect any big karate chops just yet. The first kicks, called quickening or flutters, are so subtle that they're often mistaken for stomach rumblings or indigestion -- and many first-timers may have a hard time detecting them initially.

Weekly Tip

Even if you didn't experience constipation in the first trimester, you could experience it now as the hormone progesterone relaxes smooth muscle tissue throughout your body including your gastrointestinal tract which slows down digestion and also leads to gas, bloating, and burping. In fact, constipation affects about half of all pregnant women. Laxative pills or mineral oils aren't a good idea during pregnancy, but lots of fluids and fiber can help. To help remedy your stomach woes, it's a good idea to cut back on foods that make gas worse, such as beans, cabbage, and dairy products.

Pregnancy Confidential Podcast

Home, Hospital or Birthing Center? You Decide.

Decisions, decisions, decisions: pregnancy can feel a little full of them at times. But at Week 16 you're at the best part of your pregnancy, some say—the bit where the first trimester ickiness is in the rearview mirror and your barely­-there bump is far from holding you back. If you're feeling full of energy and ready to organize the world, now might be a great time to consider your birthing options. While some of your options may be dictated by your type of provider, it's never too late to change your mind, or get educated on your choice of where you deliver.

This Week's To-Do List