21st Week Growth...

How your baby's growing:
Your baby now weighs about three-quarters of a pound and is approximately 10 1/2 inches long. His eyebrows and eyelids are fully developed. And you can certainly feel him move. He's oblivious to your schedule, though, so don't be surprised if he starts working out just when you're settling down for the night. If you're having a girl, her vagina is formed now, though it will continue to develop until birth.

By the end of this week, he'll measure about 7 inches from crown to rump and weigh nearly a pound. Not bad for a little guy who weighed barely an ounce 10 weeks ago! His hearing is developing, and sounds from your conversations can be heard inside the uterus--along with your heartbeat, stomach rumblings, and the pulsing of blood vessels. In fact, the womb is so noisy that it's been compared to an airport runway during takeoff; it's thought that the stimuli prepare the baby for the cacophony of noises, sights, and sounds that will greet him at birth.

What does a baby dream about as she drifts lazily in the womb? We may never know, but beginning with this week a baby's sleep begins to settle into identifiable patterns. You might be able to tell when Baby is sleeping if you notice that her movements slow down dramatically at certain times of the day.
Some experts believe that your eating and sleeping habits, along with how much light and noise there is in your environment, all combine to help Baby synchronize her internal clock.
Here are some other developmental highlights that occur this week:
At this point, Baby's brain will be growing very quickly, especially the structure deep in the center of the brain responsible for producing brain cells. This structure will disappear shortly before birth.
During this week, Baby's general growth pattern will slow down. However, different organs will continue to mature, Baby's heart will get stronger and her legs will reach the correct proportions.

How your life's changing:
You're probably feeling pretty comfortable these days. You're not too big yet, and the usual aches and pains associated with early pregnancy are, for the most part, gone. Relax and enjoy it while you can — the third trimester will bring some mild discomfort from carrying a baby who is nearly full-term.That's not to say you don't have some minor glitches to deal with now. Increased oil production may have given you a mild case of acne, for example. If that's the case, be diligent about washing well with a gentle soap and water twice a day, but don't take any oral acne medications — or even use any topical acne products — without checking with your practitioner first.You're also prone to varicose veins now (especially if your mom has them). That's because pregnancy puts added pressure on the veins in your legs. (Your blood volume is increased and your uterus puts pressure on the inferior vena cava, the large vein that returns blood from the lower half of your body to your heart.) As if that's not enough, an increase in the hormone progesterone causes the walls of your blood vessels to relax, so as your baby and uterus grow, the veins can become more and more prominent. Varicose veins tend to worsen with each pregnancy, and while they're most likely to show up in your legs, they can also appear on your vulva. If your legs ache, put maternity support hose on first thing in the morning. Increasing your circulation with a brisk walk each day can also help, as can elevating your legs and sleeping on your left side with your feet propped up with a pillow.
The average mom has now gained between 10 and 15 pounds. You may put on as much as a pound a week from now on.
If you're feeling out of breath around week 21, don't worry that you’re out of shape. As your body continues to change to accommodate Baby, and your expanding uterus further compresses your lungs, breathlessness usually becomes more pronounced. You may also notice your back aching a bit now, so it's a good idea to be conscious of your posture and take care to lift and carry properly.
Sometime in your second trimester (typically between weeks 24 and 28), you may be asked to take a glucose tolerance test to determine whether you have gestational diabetes. Diabetes is caused by a malfunction in the hormone insulin, which regulates the level of sugar (glucose) in your blood. Gestational diabetes is a form of diabetes that can develop in pregnant women who were not diabetic before their pregnancies. Although it often goes away after the birth, it can lead to macrosomia (high birth weight, generally defined as over 10 pounds) along with other, less common, complications.
The glucose tolerance test is simple: You'll be asked to drink a sweet, syrupy solution and then wait for an hour. At the end of that time, a blood test can determine whether your body is processing the glucose properly. About 15 percent of women will have abnormal results. If you're one of them, you will be asked to take another, more complex version of the test. Roughly 15 percent of the second group will be diagnosed with gestational diabetes. In most cases, it can be controlled through simple changes in your diet.