Week 15

According to WEBMD.COM, here is what is happening.

Week 15
Your 13-week-old fetus now measures about 4.1 to 4.5 inches from crown to rump and weighs about 1.75 ounces. Its body is covered by an ultrafine hair, called lanugo, which is usually shed by birth. Eyebrows and hair on the top of the head are beginning to grow. He may even be sucking his thumb by now. Bones are getting harder.
Your uterus can probably be felt about 3 to 4 inches below your navel. Sometime in the next five weeks you'll be offered a quadruple marker screening test, which measures four chemicals in your blood -- alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), inhibin A, and estrogen produced by the placenta. The test is a more accurate predictor of Down syndrome than AFP testing alone. Amniocentesis, which tests a small sample of amniotic fluid withdrawn by an ultrasound-guided needle, is usually performed between now and 18 weeks. It may be recommended if you're 35 or older or if your AFP or quadruple marker screen test results were suspicious.
Tip for the Week:
Start learning to sleep on your left side because circulation is best that way. Lying on your back or stomach after about the fourth or fifth month can put extra pressure on your growing uterus and decrease circulation to your baby. You can try tucking pillows behind you and between your legs. Some manufacturers make a pregnancy pillow that supports your entire body.