What to Expect at 13 Weeks Pregnant

Reviewed by Terri Forehand RN
Fetus at 13 weeks

You are now in the second trimester of your pregnancy! This means you're about a third of the way to meeting your little one. Your chance of miscarriage has also dropped significantly, and many women choose this time to announce their pregnancy to friends and family.

Your Baby's Development

At 13 weeks, your baby is about three inches long. However, at this point in the pregnancy, every baby grows at a different rate. No matter how quickly he or she is putting on weight and gaining inches, you can expect the following developments to happen this week according to the Mayo Clinic:

  • Your little one's kidneys are beginning to produce urine. Right now, your baby will release urine into the amniotic fluid, and your body will filter it. In a few short months, you'll be changing diapers instead.
  • At this point, your baby's head comprises up to half of his or her length, but that's about to change. Your little one's body is growing quickly now to catch up. At 40 weeks, your baby's head will be only 1/4 the size of his or her body.
  • Your little one's arms, legs, and head are beginning to develop a tissue that will eventually become bone.
  • Your baby is moving around a lot during this time, although, you will probably not be able to feel it. Quickening, or the first time you feel the baby move, will be happening sometime in the next few weeks.
  • Previously your baby's intestines have been developing outside his/her body in the umbilical cord. Now, the intestines will be drawn back into the abdominal cavity.

Your Changing Body

Now that you've entered the second trimester, there are some important things happening in your body. You'll notice yourself feeling a lot better too.

Placenta Has Formed

Congratulations! You've just finished growing a whole new organ: the placenta. According to Parents.com, the placenta weighs about one pound and is formed from the same type of cells as the embryo. From the time your baby implanted in your uterine wall until now, your body has been hard at work building that placenta. During this time, your body has also had to do all the work of filtering the amniotic fluid and the baby's blood and providing nutrition to your little one. Now that the placenta is formed, it can take over those important roles, leaving your body with a lot more energy. If you've been plagued by early pregnancy fatigue, you'll notice that you're starting to feel like yourself again.

Changes in Libido

Along with the increased energy, you may notice that your libido is also a little stronger, according to the American Pregnancy Association. If you've noticed a sudden increase in your libido during the 13th week of pregnancy, don't be alarmed! Since your baby is protected by amniotic fluid in the womb and a mucus plug in your cervix that guards against infection, sex during pregnancy will not harm your baby. However, your doctor may recommend that you avoid sexual activity if you have a history of premature birth, miscarriage, unexplained vaginal bleeding, placenta previa, or an incompetent cervix.

Miscarriage Risk Decreases

According to the March of Dimes, your risk of miscarriage drops to between one and five percent once you enter the 13th week of pregnancy. This is great news if you've been worried about your little one. As always, be sure to contact your doctor if you have any concerns or notice any bleeding.

More to Know About Week 13 of Your Pregnancy

The 13th week of your pregnancy is a great time to announce your good news to family and friends if you haven't already done so. Because the risk of miscarriage has decreased so significantly, this is a popular time to make the big announcement. Try some of these fun ideas for sharing your news:

  • Take a photograph of yourself and your husband wearing T-shirts that say "Mommy" and "Daddy." Have the photo made up into a greeting card, and send it out to loved ones.
  • If you've had an ultrasound already, scan the photo and post it on your favorite social media site with the caption, "Coming soon...."
  • Tell your parents about the baby by getting them grandma and grandpa greeting cards.
  • Tell your family at a big holiday event, and capture the moment on film. You'll love looking back on the photo in years to come.

If you need help downloading the printable pregnancy calendar, check out these helpful tips.

Looking Forward

Now that the first trimester is behind you, you're well on your way to becoming a mom. Soon, you'll need a completely new wardrobe to show off your growing baby bump.

What to Expect at 13 Weeks Pregnant