Welcome To Week 20

Your Baby: How Big Is The Baby?

The fetus now weighs approximately 9 ounces (255g) and measures about 6.5 inches (16 cm) long. Your baby's entire body may be covered by lanugo (soft hair), with a pasty substance called vernix protecting the skin. Both lanugo and vernix may be present in varying degrees at birth, with premature babies tending to have more. Other new developments this week include the appearance of tiny toenails, the first signs of scalp hair, and less transparent skin.

Your Body: The Rh Factor In Full

During pregnancy, one of the first blood tests you take checks for the Rh factor. Determined by genes passed on from your parents, the Rh factor is a type of protein that may appear in red blood cells. If you carry it, you're considered Rh-positive; but if you don't, you're Rh-negative.

People are more likely to be Rh positive (85%) than Rh negative (15%). The problem is if the mother is Rh negative and the father is Rh positive. In that case, the following could occur:

• The baby may inherit the Rh protein from the father (i.e., your fetus would be Rh-positive)
• Your immune system might start producing antibodies against the Rh protein, because YOUR body considers the protein a foreign substance.
• Your anti-Rh antibodies could cross through the placenta into the baby's blood stream. Those antibodies will destroy the baby's red blood cells, causing mild to severe injury to the fetus, or even death.

On That Note: Everything You Ever Wanted To Know About Rh Disease And More

What if you're Rh-negative and your mate is Rh-positive? What if you were Rh-positive in a prior pregnancy? What if your mother lost a baby with Rh disease? To get answers to these questions, click on this Rh incompatibility article.

Weekly Tip

There's nothing quite like a celebration to make something memorable. Now that you're halfway through your pregnancy, do something special tonight with your beloved to mark the momentous occasion. Set up a dreamy candlelight dinner, or get dressed up and hit the town. Stamp it forever with photographs.