Fetal development takes on new meaning in the second trimester. Your baby will begin to look like a newborn — and may even be able to hear you!
As your pregnancy progresses, your baby may begin to seem more real. You may hear the heartbeat at your prenatal appointments, and your enlarging abdomen may force your favorite jeans to the back of the closet.
While you're adjusting to the changes in your body, fetal development takes on new meaning. Two months ago, your baby was simply a cluster of cells. Now he or she has functioning organs, nerves and muscles. You may be amazed by how much your baby changes from week to week.
Week 13: Baby flexes and kicks
You can't feel it yet, but your baby can move in a jerky fashion — flexing the arms and kicking the legs. This week, your baby might even be able to put a thumb in his or her mouth.
Your baby's eyelids are fused together to protect his or her developing eyes. Tissue that will become bone is developing around your baby's head and within the arms and legs. Tiny ribs may soon appear.
Week 14: Hormones gear up
The effect of hormones becomes apparent this week. For boys, the prostate gland is developing. For girls, the ovaries move from the abdomen into the pelvis.
Meconium — which will become your baby's first bowel movement after birth — is made in your baby's intestinal tract. By the end of the week, the roof of your baby's mouth will be completely formed.
Week 15: Skin begins to form
Your baby's skin starts out nearly transparent. Eyebrows and scalp hair may make an appearance. For babies destined to have dark hair, the hair follicles will begin producing pigment.
The bone and marrow that make up your baby's skeletal system are continuing to develop this week. Your baby's eyes and ears now have a baby-like appearance, and the ears have almost reached their final position.
Week 16: Facial expressions are possible
Sixteen weeks into your pregnancy, your baby is between 4 and 5 inches long and weighs a bit less than 3 ounces. He or she can now make a fist.
Your baby's eyes are becoming sensitive to light. More developed facial muscles may lead to various expressions, such as squinting and frowning. Your baby may have frequent bouts of hiccups as well. For girls, millions of eggs are forming in the ovaries.
Week 17: Fat accumulates
Fat stores begin to develop under your baby's skin this week. The fat will provide energy and help keep your baby warm after birth.
Week 18: Baby begins to hear
As the nerve endings from your baby's brain "hook up" to the ears, your baby may hear your heart beating, your stomach rumbling or blood moving through the umbilical cord. He or she may even be startled by loud noises. Your baby can swallow this week, too.
Week 19: Lanugo covers baby's skin
Your baby's delicate skin is now protected with a pasty white coating called vernix. Under the vernix, a fine, down-like hair called lanugo covers your baby's body.
Your baby's kidneys are already producing urine. The urine is excreted into the amniotic sac, which surrounds and protects your baby.
As your baby's hearing continues to improve, he or she may pick up your voice in conversations — although it's probably hard to hear clearly through the amniotic fluid and protective paste covering your baby's ears.
Thanks to the millions of motor neurons developing in the brain, your baby can make reflexive muscle movements. If you haven't felt movement yet, you will soon.
Week 20: The halfway point
Halfway into your pregnancy, your baby is about 6 inches long and weighs about 9 ounces — a little over half a pound. You've probably begun to feel your baby's movements.
Under the protection of the vernix, your baby's skin is thickening and developing layers. Your baby now has thin eyebrows, hair on the scalp and well-developed limbs.
Week 21: Nourishment evolves
Although the placenta provides nearly all of your baby's nourishment, your baby will begin to absorb small amounts of sugar from swallowed amniotic fluid. This week, your baby's bone marrow starts making blood cells — a job done by the liver and spleen until this point.
Week 22: Taste buds develop
This week, your baby weighs in at about 1 pound.
Taste buds are starting to form on your baby's tongue, and your baby's brain and nerve endings can process the sensation of touch. Your baby may experiment by feeling his or her face or anything else within reach.
For boys, the testes begin to descend from the abdomen this week. For girls, the uterus and ovaries are in place — complete with a lifetime supply of eggs.
Week 23: Lungs prepare for life outside the womb
Your baby's lungs are beginning to produce surfactant, the substance that allows the air sacs in the lungs to inflate — and keeps them from collapsing and sticking together when they deflate. "Practice" breathing moves amniotic fluid in and out of your baby's lungs.
Your baby will begin to look more like a newborn as the skin becomes less transparent and fat production kicks into high gear.
Week 24: Sense of balance develops
By now, your baby weighs about 1 1/2 pounds. Footprints and fingerprints are forming.
Thanks to a fully developed inner ear, which controls balance, your baby may have a sense of whether he or she is upside-down or right side up in the womb. You may notice a regular sleeping and waking cycle.
With intensive medical care, babies born at 24 weeks have more than a 50 percent chance of survival. Complications are frequent and serious, however, such as bleeding in the brain and impaired vision.
Week 25: Exploration continues
Your baby's hands are now fully developed, although the nerve connections to the hands have a long way to go. Exploring the structures inside your uterus may become baby's prime entertainment.
Week 26: Eyes remain closed
Your baby weighs between 1 1/2 and 2 pounds. The eyebrows and eyelashes are well formed, and the hair on your baby's head is longer and more plentiful. Although your baby's eyes are fully developed, they may not open for another two weeks.
Week 27: Second trimester ends
This week marks the end of the second trimester. Your baby's lungs, liver and immune system are continuing to mature — and he or she has been growing like a weed. At 27 weeks, your baby's length will have tripled or even quadrupled from the 12-week mark.
If your baby is born this week, the chance of survival is at least 85 percent. However, serious complications are still possible.
Taking care of your baby
Healthy lifestyle choices throughout pregnancy will support your baby's development. Consider these simple do's and don'ts:
Do:
- Take a prenatal vitamin
- Maintain a healthy weight
- Exercise regularly, with your health care provider's OK
- Eat healthy foods
- Manage stress and any chronic health conditions
- See your health care provider for regular prenatal checkups
Don't:
- Smoke
- Drink alcohol
- Use illicit drugs
- Take medication without your health care provider's OK
Your baby is growing and changing every day — and so are you. Marvel at the changes as you anticipate what's to come.
Source:
http://www.mayoclinic.com
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