Second Trimester Development
- Week 13
- Week 14
- Week 15
- Week 16
- Week 17
- Week 18
- Week 19
- Week 20
- Week 21
- Week 22
- Week 23
- Week 24
- Week 25
- Week 26
- Week 27
Third trimester development
Labor & delivery
Week 13
The fetus is now 3 to 4 inches long, crown to rump, and weighs about an ounce — about half a banana. Its unique fingerprints are already in place. And when you poke your stomach gently and she feels it, your baby will start rooting — that is, act as if she's searching for a nipple.
If you're having a girl, she now has approximately 2 million eggs in her ovaries; she will have only a million by the time she's born. She'll have fewer eggs as she gets older, and by age 17, the number will have dropped to 200,000.
As for you, the fog may be lifting, so to speak. For many women, the side effects of early pregnancy — frequent urination, intense fatigue, nausea — diminish sometime in the second trimester, which starts next week. Your uterus, while large enough to announce to onlookers that you're indeed pregnant, isn't so huge that it gets in your way. Even though birth is months away, your breasts may already start making colostrum, the fluid that will feed your baby for the first few days before your milk comes in.
Week 14
Crown to rump, your baby is about 3 1/2 inches long, and weighs 1 1/2 ounces. The body is now growing faster than the head. This week, its parchment-thin skin covers itself with lanugo (ultra-fine, downy hair that usually disappears before birth). Though eyebrows are beginning to grow and the hair atop the head is sprouting, this hair may change in both texture and color after birth. About now, the fetus can grasp, squint, frown, and grimace. It may even be able to suck its thumb. Researchers believe these and other movements probably correspond to the development of impulses in the brain.
If you haven't yet scheduled a triple-screen maternal serum (a type of blood test), you may want to do so now. The test provides more information about your baby, and screens for Downs syndrome and other birth defects. Also, healthcare providers may recommend an amniocentesis between 15 and 18 weeks for women over 35 and those with a history of birth defects.
Week 15
You may not know it when it happens, but your tiny tenant frequently gets the hiccups, which babies master before breathing; they don't make any sound because the trachea is filled with fluid rather than air. Although you've probably gained between five and ten pounds, the fetus weighs in at less than 3 ounces. Legs are growing longer than the arms now, fingernails are fully formed, and all the joints and limbs can move. Starting about now you may be able to find out the sex of your baby by ultrasound, since external genitals are developed enough that the technician can probably tell the difference between boy and girl.
If the idea of having a baby seems so remote, nothing makes it feel more real than feeling your baby move for the first time. Most moms-to-be discern movement (called quickening) between 16 and 20 weeks. If you've been pregnant before, you'll feel things earlier rather than later. What you may first think is a rumbling stomach may be junior doing some back flips. Make note of when you first start feeling the baby, and tell your healthcare provider at your next visit.
Week 16
Your baby is now about the size of an avocado (about 4 1/2 inches long, crown to rump, and weighing approximately 3 1/5 ounces). In the next three weeks he'll go through a tremendous growth spurt, doubling his weight and adding inches to his length.
In or out of the womb, babies are playful creatures. Yours may already have discovered his first toy — the umbilical cord — which he'll enjoy pulling and grabbing. Sometimes he may even clutch it so tight that less oxygen gets through, but don't worry — he doesn't hold onto it long enough to harm himself. The circulatory system and urinary tract are in full working order, and he's inhaling and exhaling amniotic fluid through his lungs.
Sometimes, when you move suddenly, you may a feel a slight pain in your sides. Ligaments on each side of your uterus and pelvic walls are stretching as your baby grows. It's normal to feel some pain, but if it continues for a few days or escalates, talk to your healthcare provider.
Week 17
Your baby is now just over 5 inches long and weighs approximately 5 ounces. Her skeleton is mostly rubbery cartilage, which will harden later. A protective substance called myelin slowly begins to enshroud the spinal cord.
With the help of a special stethoscope, you can now hear your baby's heartbeat. Although you probably already heard it weeks ago in your doctor's office, there's almost nothing more comforting or exciting than hearing your baby's heartbeat galloping along. On days when you're worried about how your pregnancy is progressing, hearing the heartbeat lets you know that your baby's developing and growing. For times when boredom strikes and you feel as if you'll be pregnant forever, it can be a pleasant reminder of what will come at the end of 40 weeks of waiting.
Your growing uterus has shifted your center of gravity, and you've probably been feeling a bit off-kilter. Be careful and wear low-heeled shoes. If you haven't had an amniocentesis yet and plan to, do it this week. One perk: You'll get a long look at your baby through ultrasound during this procedure.
Week 18
Your baby is approximately 5 1/2 inches long, crown to rump. Her chest moves up and down to mimic breathing, but she's not taking in air, only amniotic fluid.
A midpregnancy ultrasound is often done sometime in the second trimester (usually between 18 and 22 weeks) to assess fetal growth and development, screen for certain birth defects, check the placenta and umbilical cord, and determine whether the gestational age is accurate. During this exam, you might see your baby kick, flex, reach, roll, or even suck its thumb. Bring your partner along, and whether or not he's able to accompany you, make sure to ask for printouts of the baby in various poses.
If you're having a girl, the vagina, uterus, and Fallopian tubes are in place. If it's a boy, the genitals may be distinct and recognizable. In some cases, though, the male genitals may be hidden due to the baby's position, making it hard or impossible to determine the child's gender during any given exam.
Week 19
The top of your uterus now reaches your belly button and will grow about a centimeter per week. Your baby is about 6 inches long (crown to rump) and weighs about 8 ounces.
She has started to swallow amniotic fluid, and her kidneys continue to make urine. Hair on the scalp is sprouting.
Sensory development reaches its peak this week. The nerve cells serving each of the senses — taste, smell, hearing, seeing, and touch — are now developing in their specialized areas of the brain. Nerve cell production slows down as existing nerve cells grow larger and make more complex connections. If you're carrying a baby girl, she already has roughly 6 million eggs in her ovaries. But since most of them will disintegrate during gestation, by the time she's born, she'll have about a million.
Week 20
The baby is steadily gaining weight to stay warm after birth. A whitish coat of a slick, fatty substance called vernix caseosa begins to enshroud your baby and protects the skin during its long immersion in amniotic fluid. It also eases delivery. The baby's swallowing more this week, good practice for the digestive system. After your baby takes in amniotic fluid, his body absorbs the water in the liquid and moves the rest into the large bowel.
You may want to look into a childbirth education class if you haven't done so already. If you're a first-time parent or want a refresher course, you'll benefit from a structured class either way. No matter what the philosophy behind it, a childbirth class can help prepare you for the rigors of labor and delivery. At 37 weeks, you'll be considered full-term and labor could start any minute, so plan to be done with classes by then.
Be extra vigilant about getting enough iron. Your baby needs it to make red blood cells, among other things. In fact, it's almost impossible for you to get too much from food alone without overeating. Iron-rich foods include lean red meat, poultry, fish, lentils, spinach, and iron-fortified cereals.
Week 21
The fetus now weighs about three-quarters of a pound and is approximately 10 1/2 inches long. The eyebrows and eyelids are fully developed, and the fingernails cover the fingertips.
Little pitchers have big ears, all right. Your baby can now hear your conversations. If you talk, read, or sing to your baby, expect her to hear you. Some studies have found that newborns will suck more vigorously when read to from a book they heard frequently in utero. If you want to try, pick a book now and read it out loud. Make sure you won't mind reading it over and over once the baby is here. It may be your baby's favorite bedtime story for a long time after birth.
You're probably feeling quite comfortable these days. This, in fact, may be the most enjoyable time in your pregnancy. You're not too big yet, and the usual aches and pains associated with pregnancy — nausea, frequent urination, and fatigue — are for the most part gone. Relax and enjoy while you can — the third trimester is just around the corner, and with it comes some mild discomfort from carrying a baby that is nearly full-term.
Week 22
The baby now weighs almost a pound, measures nearly 11 inches long, and is proportioned like a newborn, albeit a thinner version since her baby fat hasn't yet developed. Although she's getting heavier every day, her skin still appears wrinkled because she needs to gain more weight. The lips are distinct and the eyes are formed, though the iris (the colored part of the eye) still lacks pigment. The pancreas, essential in the production of hormones, is developing steadily.
Even this early, the first signs of teeth appear in the form of tooth buds beneath the gum line. Before you know it, your baby will be born, and soon after, flashing his pearly whites.
You've likely gained between 12 and 15 pounds. Starting now you'll begin to put on weight more steadily, averaging about half a pound per week. You may crave certain foods, and you may notice an increased (but not bloody) vaginal discharge. Both are a normal part of being pregnant.
Week 23
Your baby now weighs a little over a pound. Her hearing is well established, and she can make out a distorted version of your voice, the beating of your heart, and your stomach rumblings. Loud noises often heard in utero, such as the barking of a dog next door or the roar of a vacuum cleaner, probably won't faze your child when she hears them outside the womb. Numerous studies seem to indicate that the unborn prefer classical music, especially Vivaldi. Play "The Four Seasons" for your child, and pay attention to her movements. Does she quiet down during adagio sections, and speed up for the allegro portions? You may have a budding conductor in your womb.
In addition to advances in your baby's hearing, blood vessels in the baby's lungs are developing to prepare for breathing. She's swallowing, but usually won't pass stool until after birth.
If your baby were to be born now, she would still have a good chance of survival (about 85 percent) with the right care. Advances in science and technology now mean that a 24-week-old baby can grow outside the womb if necessary, although about 50 percent of children in this situation will have some severe and permanent damage.
As for you, you may feel clumsy now that your center of gravity has shifted; your gums may bleed when you brush your teeth, and your belly button, once an "innie," may now stick out. Don't worry — it'll revert to its pre-baby state soon after you give birth.
Week 24
The baby weighs more than 1 1/4 pounds. Though it still has little body fat and its skin is thin and fragile, it's now well-proportioned. The brain is growing rapidly, and the baby is starting to fill the space in your uterus. If you went into labor at this time, however, many healthcare providers would make every effort to halt the progress of preterm labor to enable the fetus to continue maturing.
You may be noticing faint, red streaks--otherwise known as striae or stretch marks--on your abdomen, hips, and breasts. While creams won't erase them, wearing a supportive bra may help prevent or minimize them on your breasts. They are typical developments at this stage of the pregnancy and they will fade to silvery, white marks after giving birth. Also, your eyes may be light-sensitive and may feel gritty and dry. This is a perfectly normal pregnancy symptom known as dry-eye. To ease your discomfort, use an "artificial tears" solution to add moisture.
Week 25
The baby now weighs about 1 1/2 pounds and is approximately 12 1/2 inches long. He makes breathing movements, but has no air in his lungs yet. At this point, fetal brain scans show response to touch. If you shine a light on your abdomen, your baby will turn his head, which, according to researchers, means the optic nerve is working.
Sometime soon, you'll need to take a glucose screening test. You'll drink a glass of glucose water (it tastes like an intense orange soda) at your next doctor's visit. Then she'll take a sample of your blood for testing. If the reading is abnormal, which happens about 20 percent of the time, you'll be given a similar but lengthier exam called a glucose tolerance test at a later date to determine whether you have gestational diabetes, or excess sugar in your blood, a common ailment at this stage of pregnancy.
Your fingers, wrists and hands may be feeling achy and numb. The carpal tunnel in the wrist is swollen, as are many other tissues in your body. Nerves that run through the tunnel end up pinched, creating pressure that manifests itself as shooting or burning pain. Wearing a brace may help; so will taking vitamin B6. Talk to your midwife or doctor about other ways to cope.
Week 26
Your baby now weighs about 1 3/4 pounds and is about 13 inches long with its legs extended. Your baby's eyes begin to open around now. Response to sound grows more consistent toward the end of the seventh month, when the network of nerves to the ear is complete. He also continues to take small breaths, and although he's only breathing in water and not air, it's still good practice for when he's born.
You should boost your intake of grains and legumes by about a serving a day from now until you deliver since your baby needs the extra nutrients. Fiber-rich foods, including whole grain breads and cereals, lentils, and brown rice, are high in vitamin B and help fend off constipation.
Your childbirth class should start sometime in the next few weeks, if it hasn't already. Take notes in class so you can review them if you get nervous about labor later. Keeping informed goes a long way toward calming any concerns you may have about giving birth.
Week 27
The baby now weighs about 2 pounds. Her eyes open and close, and she sleeps and wakes at regular intervals and may suck a finger or thumb.
Sweet dreams, little baby! Some experts believe that babies begin to dream by the 28th week. What do they dream about? No one knows for certain. But the brain is active this week as well. The characteristic grooves on the brain's surface start to appear, and more brain tissue develops.
Chalk up any rhythmic movement you may be feeling to a case of the hiccups, which are common this week and throughout the pregnancy. Your baby has them, but is breathing in amniotic fluid rather than air. A paper bag can't cure her hiccups, obviously, but an episode usually lasts only momentarily. Besides, it may feel like a belly tickle, so enjoy.
Since your uterus is now up near your rib cage, you may now find yourself short of breath if you haven't already. Starting now, and continuing through the last three months of pregnancy, you may be plagued by leg cramps, hemorrhoids, varicose veins, and an itchy abdomen. If you were found to be Rh-negative earlier in pregnancy, you'll probably be tested for Rh antibodies this week or next and get an Rh-immune globulin injection to combat the incompatibility.
First trimester developmentThird trimester development
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