How Your Baby Grows During the Twentieth Week
The crown-to-rump length of your baby is around 5 1/2 to 6 1/2 inches long. As your baby gets older, the possible length will increase, since a full-term baby is anywhere from 17 to 22 inches long - both are "normal" even though the difference is fairly significant. She now weighs around half a pound, or more.

Her body is producing a white, paste-like substance called vernix which covers her entire body. This cheesy substance protects her skin from the amniotic fluid and will be rubbed into the skin, or gently washed off, after she is born.

An ultrasound at this stage of your pregnancy would easily reveal the gender of your baby, assuming she cooperates of course. Interestingly, a girl baby has all the eggs she'll ever produce, already formed in her tiny ovaries before birth. While the eggs won't mature until she hits puberty, it is amazing to think that before you've even given birth to her, all of her genetic contribution to your future grandchildren, is already in place.

What the Mother Feels During the Twentieth Week
Congratulations! You are now halfway through your pregnancy. Your uterus now reaches to your belly button and, as a result, continues to put pressure on the rest of your body.

You may notice that your belly button is beginning to flatten out and many pregnant women even find themselves with "outies" before the end of their pregnancies. This is normal and your belly button will return to normal after your delivery.

Your stretching uterus also puts pressure on the abdominal muscles, especially the rectus muscles. In fact, some pregnant women will experience a separation of these muscles, called diastatis recti, and may need to do special exercises postpartum to help the muscles come back together properly.

As you pass this milestone "half-way" point your pregnancy will seem to progress quicker than ever. Your prenatal visits will soon be closer together, your transition into maternity clothes is now likely complete, and soon total strangers will smile at you and comment on your beautiful pregnancy glow or inquire about your due date.

Resources:
The Pregnancy Book: Month-by-Month by Dr. Sears

Your Pregnancy Week by Week by Lesley Regan

The Complete Book of Pregnancy and Childbirth by Sheila Kitzinger