20th Week Growth... (Half-Way Mark)

How your baby's growing: Your baby weighs about 10 1/2 ounces now. She's also around 6 1/2 inches long from head to bottom, and about 10 inches from head to heel. (For the first 20 weeks, we use measurements taken from the top of the baby's head to her bottom — known as the "crown to rump" measurement. After that, we use measurements from head to toe. This is because a baby's legs are curled up against her torso during the first half of pregnancy and are very hard to measure.) A greasy white substance called vernix caseosa coats her entire body to protect her skin during its long submersion in amniotic fluid. (This slick coating also eases the journey down the birth canal.)Your baby is swallowing more, which is good practice for her digestive system. She's also producing meconium, a black, sticky substance that's the result of cell loss, digestive secretion, and swallowed amniotic fluid. This meconium will accumulate in her bowels, and you'll see it in her first messy diaper (although a few babies pass it in utero or during delivery).

This week marks the halfway point in your baby's development. And right around now, nature gives her a spa treatment--a white, cream-cheesy moisturizer called vernix coats every inch of her skin, keeping it smooth and wrinkle-free for the next 20 weeks as she floats in a warm bath of amniotic fluid. She'll still be covered in vernix when she's born; your doctor or midwife will wipe it off a few moments after birth, revealing skin that's (you guessed it) baby soft.

The 20th week is an important time for Baby's sensory development, as nerve cells serving each of the senses (taste, smell, hearing, seeing, and touch) are now developing into their specialized area of Baby's brain. As these existing nerve cells get bigger and make more complex connections with each other, the brain's production of additional nerve cells will slow.
Believe it or not, you're halfway there on the journey toward holding your new baby! Your little one now weighs about nine to 12 ounces and has grown to about six to eight inches in length. She's come a long way since her first days as a microscopic collection of cells, but has a lot more growing to do—remember, the average newborn is 18 to 21 inches long and weighs six to nine pounds at birth.Other baby developments this week include:
*Under the protective vernix coating, Baby's skin will continue to develop into three layers: the dermis, epidermis and subcutaneous layers.
*Baby's nails and hair will continue to grow.
*Baby's heartbeat will be stronger now, and will beat about twice as fast as your heart. You can hear it this week through a stethoscope.
*Baby will take up more and more space in the uterus, and her continued growth will put more pressure on your lungs, stomach, bladder, and kidneys.

How your life's changing:
You've made it to the halfway mark — Congratulations! The top of your uterus is at the level of your belly button now, and you've likely gained about 10 pounds. Expect to gain an average of about another pound each week from now on. (If you started your pregnancy underweight, you may need to gain a bit more; if you were overweight, perhaps a bit less.) Make sure you're getting enough iron, a mineral that's used primarily to make hemoglobin (the part of your red blood cells that carries oxygen). During pregnancy, your body needs more iron for your developing baby and the placenta, and to keep up with your expanding blood volume. Iron-rich foods include lean red meat, poultry, fish, lentils and other legumes, spinach, and iron-fortified cereals.If you haven't already signed up for a childbirth education class, you may want to look into one. Whether you're a first-timer or a pro, you can benefit from a structured class that helps prepare you for the rigors of labor and delivery. Most hospitals and birth centers offer classes, either as weekly meetings or as a single intensive, all-day session. Ask your doctor or midwife for a recommendation. At 37 weeks, you'll be considered full-term, so plan to be done with classes by then.

You may notice that it's harder to keep your balance lately: As one mom-to-be put it, you feel as "clumsy as a pregnant ox." The growing weight of your uterus has caused a change in your center of gravity. Gradually, sometimes without even knowing it, you adjust your posture and the way that you move to compensate. If you're not careful, this can cause back pain or other injuries. Practice correct posture (hips and shoulders in line as you walk--avoid the "pregnancy slouch"), sit with your feet slightly elevated, and sleep on your side with knees and hips bent to relieve the strain.

There are a few things that you may be experiencing for the first time when you reach the midpoint of your pregnancy at week 20. One change is that your uterus has reached your navel. At 20 weeks, your uterus is probably growing at about 4/10 inch a week. (If you're much bigger, your doctor may perform an ultrasound to see if you're carrying twins or if your estimated due date is correct.)
The enlarging uterus also will begin to stretch your abdominal muscles, and they may begin to pull apart as Baby grows. First-time moms may not notice such a separation, but with each pregnancy it becomes more visible. These muscles are attached to the lower part of your ribs and stretch down to the pelvis. You can see the separation more clearly if you lie down and raise your head, tightening the abdominal muscles — you'll notice a bulge in the middle of your abdomen. It isn't harmful or painful, and although exercising can strengthen these muscles, the bulge will still occur. After you give birth, these muscles will return to their original place, and the separation will become less noticeable.
You may also notice your skin is getting itchy as the uterus grows. This is because as your uterus grows, it stretches your skin. Lotions may help soften skin and ease the itch.
Don't be surprised if your belly button has changed from an "innie" to an "outie" and starts to protrude. This change is a result of the pressure behind it. (It will revert close to its pre-pregnancy shape after delivery.)
Other changes you may notice this month include the appearance of varicose veins. Most women who experience varicose veins are genetically predisposed to this condition. Varicose veins are simply blood vessels that are filled with pooled blood. They usually appear in the legs or vulva. Wearing support hose, lying on your left side and elevating your legs can help drain the veins. It's also as good idea to stay off your feet, wear flat shoes and avoid crossing your legs. Varicose veins usually become less noticeable after delivery.
Additionally, you may suddenly find yourself short of breath. Some women have a bit of trouble catching their breath as their internal organs press against the lungs. This breathlessness will usually continue until the baby “drops” or moves into position in the pelvis (for first pregnancies, this usually happens four to six weeks before birth; with subsequent pregnancies, it occurs closer to when labor begins).