Second trimester: Your growing baby

The second trimester is a time for your baby to grow bigger andstronger.

By the end of the second trimester your baby will weigh about two pounds and measure about 12 inches from crown (top of the head)to rump (buttocks).

Your baby's gender can be identified in thefourth month. However, some babies don't provide a clear enoughview during an ultrasound to tell for sure.

Although you can't feel it, your baby is very active. She cankick her legs, move her arms, turn her head and suck a finger orthumb. Your baby is also swallowing amniotic fluid, the fluid thatsurrounds her, and passing it as urine.

Although she is gettingoxygen through the placenta and umbilical cord, your baby practicesbreathing movements. Her skin is now covered with a fine, downy haircalled 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 beforefamily members will be able to feel your baby's movements.

During the fifth month, your baby's activity grows morecoordinated. She can turn somersaults and make faces.

An ultrasoundmay show her frowning or grimacing. Your baby also has eyebrows andis growing hair. Her skin becomes covered with a protective, whitecoating called vernix.

By the end of the second trimester, your baby hears and respondsto sounds. Loud noises may startle her, making her move. She islistening to your voice and will recognize it after she is born.

She will recognize the voices of other family members, too. Each ofyou can sing or play a song that is "your song." Your baby willrecognize it after birth and quiet when she hears it.

Your baby is also opening and closing her eyes and reacting tolight. She can make a fist and grasp the umbilical cord. You mayfeel her pushing her feet against the wall of your uterus as if sheis walking. The rhythmic movements you sometimes feel arehiccups.

Baby's development: Weeks 14 to 26

Week 14

Hair and eyebrows are growing. Heartbeat is strong enough tohear with ultrasound. Starts to drink amniotic fluid (the fluidsurrounding 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 allover body and face. External genital organs are developed enough tobe seen with ultrasound. Developing skin is transparent.

Week 17

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

Week 18

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

Week 19

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

Week 20

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

Week 21

Skin is becoming opaque. Tongue is fully developed.

Week 22

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

Week 23

Heartbeat can be heard with a stethoscope.

Week 24

Illustration of baby at week 24Vitalorgans are developed enough for the baby to survive outside thewomb. Lungs are immature, however, and the baby would needbreathing assistance if born now. Baby measures about 14 incheslong 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, seventh edition, ob-ah-90026
First Published: 10/04/2002
Last Reviewed: 12/02/2015

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