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Beginnings: Pregnancy, Birth & Beyond

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Second trimester: Your growing baby

The second trimester is a time for your baby to grow bigger and stronger. By the end of the second trimester your baby will weigh two pounds and measure about 12 inches from crown (top of the head) to rump (buttocks). Your baby's gender can be identified in the fourth month. However, some babies don't provide a clear enough view during an ultrasound to tell for sure.

Although you can't feel it, your baby is very active. She can kick her legs, move her arms, turn her head, and suck a finger or thumb. Your baby is also swallowing amniotic fluid, the fluid that surrounds her, and passing it as urine. Although she is getting oxygen through the placenta and umbilical cord, your baby practices breathing movements. Her skin is now covered with a fine, downy hair called lanugo.

At about 20 weeks, earlier if you have already had a baby, you'll probably feel the first flutters of your baby's movements. This is called quickening. It will be several more weeks before family members will be able to feel your baby's movements.

During the fifth month, your baby's activity grows more coordinated. She can turn somersaults and make faces. An ultrasound may show her frowning or grimacing. Your baby also has eyebrows and is growing hair. Her skin becomes covered with a protective, white coating called vernix.

By the end of the second trimester, your baby hears and responds to sounds. Loud noises may startle her, making her move. She is listening to your voice and will recognize it after she is born. She will recognize the voices of other family members, too. Each of you can sing or play a song that is "your song." Your baby will recognize it after birth and quiet when she hears it.

Your baby is also opening and closing her eyes and reacting to light. She can make a fist and grasp the umbilical cord. You may feel her pushing her feet against the wall of your uterus as if she is walking. The rhythmic movements you sometimes feel are hiccups.

Baby's development: Weeks 14 to 26

Week 14

Hair and eyebrows are growing.
Heartbeat is strong enough to hear with ultrasound.
Starts to drink amniotic fluid (the fluid surrounding the baby).

Week 15

Middle ear bones harden, so baby can hear.

Week 16

Illustration of baby at week 16Fine, downy hair called "lanugo" appears all over body and face.
External genital organs are developed enough to be seen with ultrasound.
Developing skin is transparent.

Week 17

Baby can hear sounds outside the mother's body and will jump when startled.
Fingernails and toenails begin to appear.
Baby may begin thumb-sucking.

Week 18

Baby is moving much of the time now.
Skeleton would be clearly outlined if X-ray was performed.
Baby measures 8 inches long.

Week 19

Buds for permanent teeth begin to form.
Baby drinks amniotic fluid, which is filtered through the kidneys and excreted back into the amniotic sac.
Baby may get hiccups.

Week 20

Illustration of baby at week 20Baby's movements can now be felt by mother.
Baby is 8 1/2 inches long and weighs 8 to 16 oz.

Week 21

Skin is becoming opaque.
Tongue is fully developed.

Week 22

Vernix, a greasy, white, cheesy-looking substance, is beginning to form on the baby's skin to protect it (most of the vernix will disappear before birth).

Week 23

Heartbeat can be heard with a stethoscope.

Week 24

Illustration of baby at week 24Vital organs are developed enough for the baby to survive outside the womb.
Lungs are immature, however, and the baby would need breathing assistance if born now.
Baby measures about 14 inches long and weighs 1 to 1 1/2 pounds.

Week 25

Bone centers begin to harden.

Week 26

Fat stores are beginning to form.


 

Source: Allina Health's Patient Education Department, Beginnings: Pregnancy, Birth and Beyond, sixth edition, preg-ahc-90026, ISBN 1-931876-25-8

First published: 10/04/2002
Last updated: 08/22/2011

Reviewed by: Allina Health's Patient Education Department experts