The second trimester is week 13 through week 26 of your pregnancy. During this time, your baby continues to grow, develop and change almost daily.
When the second trimester starts, your baby is about 3 inches long. Your doctor might tell you your baby measures a certain length “from crown to rump.” This means your baby is being measured from the top of its head to its bottom (instead of head to toe) because the legs are curled up to the baby’s stomach.
At the beginning of the second trimester, your baby’s head is the biggest part of his or her body. During the next few weeks, the rest of your baby’s body will get longer in order to catch up. By the end of the second trimester, your baby may be 9 inches long—or even longer.
Your baby is moving almost all the time, but you probably won’t feel anything until about the 20th week of pregnancy. At first, you'll just notice a fluttering feeling and may not even be sure if it’s your baby or not. Soon enough, the movements will become very noticeable. Other people might even be able to see your belly move when your baby “kicks.”
Your baby’s movements are helping him or her practice for life outside your body. Muscles grow stronger as your baby learns to kick, suck and open and close his or her hands. Your baby is also practicing making faces, such as frowning, smiling and squinting.
An ultrasound may be able to reveal your baby's sex a few weeks into the second trimester. If you have an ultrasound then, you may be able learn your baby's sex, if you want to, but keep in mind your baby has to be in an ideal position for the doctor or technician to see the sex organs.
Written by familydoctor.org editorial staff
Reviewed/Updated: 02/11
Created: 10/09