Calendar of your baby’s development – 5

Week 16

Your Baby’s Development

Your baby now weighs about 3.9 ounces (110 grams) and measures about 4.7 inches (12 cm) in length from crown to rump. Your baby can hold his or her head erect, and the development of facial muscles allows for a variety of expressions, such as squinting and frowning.

Your Body

Between weeks 16 and 18 of pregnancy, your health care provider may offer you the maternal blood screening test, also known as a “triple marker” test or “triple screen,” which measures the levels of alpha-fetoprotein (AFP), a protein produced by the fetus, and the pregnancy hormones hCG and estriol in the mother’s blood. The test is sometimes called a quadruple screen when the level of an additional substance, called inhibin-A, is also measured. The results of these tests can tell moms whether their babies are at risk for (not whether they have) neural tube defects such as spina bifida or chromosomal abnormalities such as Down syndrome. Out of every 1,000 women who take these tests, about 50 will have abnormal results, but only one or two women will actually have babies with a problem. Talk to your health care provider about the risks and advantages of these tests.

Week 17

Your Baby’s Development

At about 5.1 inches (13 cm) from crown to rump and weighing 4.9 ounces (140 grams), your baby is still very tiny.

The placenta, which nourishes the fetus with nutrients and oxygen and removes wastes, is growing to accommodate your baby. It now contains thousands of blood vessels that bring nutrients and oxygen from your body to your baby’s developing body.

Your Body

You may notice that your breasts have changed considerably since your pregnancy began. Hormones are preparing your breasts for milk production — more blood is flowing to the breasts, and the glands that produce milk are growing in preparation for breastfeeding. This can increase your breast size (many women increase one to two cup sizes) and cause veins to become visible. Buy supportive bras in a variety of sizes to accommodate your breast growth during pregnancy.

Week 18

Your Baby’s Development

Ears move to their final position and they stand out from the head. And start brushing up on your lullabies — in the coming weeks, your baby will probably be able to hear! The bones of the middle ear and the nerve endings from the brain are developing so that your baby will hear sounds such as your heartbeat and blood moving through the umbilical cord. He or she may even be startled by loud noises! Your baby’s eyes are also developing — they’re now facing forward rather than to the sides, and the retinas may be able to detect the beam of a flashlight if you hold it to your abdomen.

Until now, your baby’s bones had been developing but were still soft. This week, they begin to harden, or ossify. Some of the first bones to ossify are those in the clavicles and the legs.

Your Body

You’re probably beginning to prepare for life with baby. Your preparations should extend beyond gathering the layette and decorating the nursery, though. This is a good week to begin your search for a pediatrician or other health care provider for your child. Schedule visits to meet with potential doctors to discuss issues such as appointment availability, immunization scheduling, and when to call in an emergency. You’ll also want to learn as much as you can about their practices and procedures.

Some good questions to ask: How many health care providers are in the practice? Who covers nights and weekends? What is their policy on phone calls? Which hospitals are they affiliated with? What insurance do they accept? What specialists do they work with? How are emergencies handled?

It’s important that you feel comfortable with your child’s doctor, so do your homework and make your decision carefully.

Week 19

Your Baby’s Development

Your baby is now covered with a white, waxy substance called vernix caseosa, which helps prevent delicate skin from becoming chapped or scratched. Premature babies may be covered in this cheesy coating at delivery.

Your baby is still tiny, but this week brings the development of brown fat, which will help keep your baby warm after birth. During the last trimester, your baby will add more layers of fat for warmth and protection.

Your Body

Your constant concern for your baby’s health may give way to reassurance if you feel your baby’s first movements, which often happens between weeks 18 and 20. These first movements are known as quickening, and they may feel like butterflies in your stomach or a growling stomach. Later in your pregnancy, you’ll feel kicks, punches, and possibly hiccups! Each baby has different movement patterns, but if you’re concerned or if the movements have decreased in frequency or intensity, talk to your doctor.

Many women wonder around this time whether having sex will hurt their developing baby, and the answer is no. Sex is considered safe at all stages of pregnancy, as long as your pregnancy is normal. But that doesn’t necessarily mean you’re going to want to have it. Many expectant women find that their desire for sex fluctuates during the various stages of pregnancy, depending on their fatigue, growing size, anxiousness over the birth, and a host of other body changes. Keep the lines of communication with your partner open as these issues come up. Even though you may both be preoccupied with the baby, it’s also important to have some “together time.”

Week 20

Your Baby’s Development

You’re halfway there! Twenty weeks into your pregnancy, your baby has grown significantly from that first dividing cell and now weighs about 11 ounces (312 grams) and measures about 6.3 inches (16 cm) from crown to rump. The baby is taking up increasing room in your uterus, and continued growth will put pressure on your lungs, stomach, bladder, and kidneys.

Under the vernix caseosa (a protective, waxy coating), your baby’s skin is thickening and developing layers. Hair and nail growth continue.

Your Body

If you haven’t already had one, your health care provider may recommend that you receive an ultrasound, a diagnostic test that uses sound waves to create an image. An ultrasound can determine the size and position of the fetus, and any structural abnormalities of bones and organs that are visible by this time. Depending on the position of the fetus, the sex can usually be determined by now. During an ultrasound, the umbilical cord, placenta, and amniotic fluid can also be examined. Talk to your health care provider about the risks and advantages of this test.

Week 21

Your Baby’s Development

The amniotic fluid that has cushioned and supported your baby in the uterus now serves another purpose. The intestines have developed enough that small amounts of sugars can be absorbed from the fluid that is swallowed and passed through the digestive system to the large bowel. Almost all of your baby’s nourishment, however, still comes from you through the placenta.

Until now your baby’s liver and spleen have been responsible for the production of blood cells. But now the bone marrow spaces are developed enough to contribute to blood cell formation as well, and bone marrow will become the major site of blood cell production in the third trimester and after birth. (The spleen will stop producing blood cells by week 30, and the liver will stop a few weeks before birth.)

Your Body

Is exercise safe during pregnancy? Exercise can be a great way to stay in shape during pregnancy and can even keep some symptoms — such as varicose veins, excessive weight gain, and backache — to a minimum. But pregnancy is not the time to start training for a triathlon — going slowly is the name of the game. Because ligaments become more relaxed during pregnancy, you’re at higher risk for injury, so low- or non-impact exercise such as yoga, swimming, and walking are your best bets. Talk to your health care provider before beginning any exercise program while you’re pregnant.

source:   http://kidshealth.org/parent/pregnancy_calendar/pregnancy_calendar_intro.html