Pregnancy Week 15

Find out how your baby is developing in week 15 as well as what tests you should ask your doctor about including a multiple marker screening test, an amniocentesis, and an Rh blood test.

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

How big is baby?

Your baby is now the size of an apple. His brain now controls all the muscles in her body; he is able to move. Yes, he'll even do somersaults! But if this is your first baby, you probably won't feel him moving for several more weeks.

Baby's Length: 3.98in.
Baby's Weight: 2.47oz.
Fetus at Week 15 What the baby looks like at week 15 of fetal development. Med ART Studios Explore More

Baby's Development

Lanugo, your baby's first ultrafine, downy hair, now covers his back, shoulders, ears, and forehead. It helps him retain body heat, but once he gains enough fat to do the job, this hair will fall off -- probably before birth. Facial expressions are your baby's newest trick -- he can frown, squint, grimace and wince. Don't worry -- he's just flexing his facial muscles, not indicating his mood.

Baby Week 15

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Although the eyelids are still closed, the eyes themselves may now perceive light and begin to track light in unison.Now about the size of an avocado, the fetus's movement is becoming more complex.The developing fetus may demonstrate more purposeful movements, such as thumb sucking.
Week by week baby ultrasound image. Week by week baby ultrasound image. American Institute of Ultrasound in Medicine - AIUM.org

Week 15 Ultrasound

In this 3-D image, the baby-to-be is curled up, her hands covering her face (she's about the size of a grapefruit). The large bones that make up her skull are forming and hardening. As they harden, the bones appear whiter and brighter in the image. These cranium pieces do not come together until well after birth.

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Watch Baby's Growth

Second Trimester Begins: Weeks 13 to 17 of Pregnancy

Mom's changing body

If you take a peek in the mirror, you might notice yet another set of strange pregnancy symptoms: Skin darkening -- most commonly around your nipples, areolas, navel, armpits and inner thighs -- affects more than 90 percent of moms-to-be. And if you have dark hair and fair skin, you're also more prone to a condition called chloasma (aka "the mask of pregnancy") -- a darkening around the eyes, nose, and cheeks. This darkening usually fades a few months after delivery (however, according to the ACOG, it's unlikely to go away completely), and there's not much you can do to prevent it. What does help? Avoid spending time in the sun and if you do go outside, wear a hat with a wide brim. You might also notice small growths of skin, or skin tags, developing during pregnancy.

Weekly Tip

Along with being known as the "feel good" trimester, trimester two is also considered the sexiest. Some women experience a boost in libido due to a hormonal change, and increased blood flow can also rev up arousal and improve orgasms. So unless your doctor has advised you against it, go ahead and indulge -- it's perfectly safe for your baby-to-be.

Pregnancy Confidential Podcast

I'm Not Fat, I'm Pregnant!

On this episode, we'll cover all you need to know about Week 15 of pregnancy. We're calling it the "I'm Not Fat, I'm Pregnant" period. I.e. the time when nothing fits right except old leggings and your stretchier tank tops, and whether or not you have a bump seems to depend on what you had for lunch that day.

This Week's To-Do List

Must-Reads

Are You Having a Boy or a Girl?

Learn why finding out Baby's gender as soon as possible is now the norm for most expectant parents.

Pregnancy Symptoms & Complaints: Acne, Chloasma, Stretch Marks and More Skin Changes

Pregnancy hormones can cause a number of skin issues, including acne, itching, darkening and stretch marks. Find out what causes these skin changes in pregnancy and what you can do to feel and look better.

Second Trimester Begins: Weeks 13 to 17 of Pregnancy

Here's to hoping you're no longer feeling nauseated or exhausted! Right now your baby's brain and eyes are making dramatic strides each day. Learn all about it.

The Inside Story: Your Baby in Week Fifteen

Your baby is starting to move -- she can now turn her head, make faces and make fists!

Your Developing Baby: Week 15

What's going on with your baby in pregnancy week 15? Find out all about important pregnancy milestones and exciting fetal development specific to this week of pregnancy!