Your Baby's Development
You're halfway there! Twenty weeks into your pregnancy, your baby has grown significantly from that first dividing cell and now weighs about 11 ounces (312 grams) and measures about 6.3 inches (16 cm) from crown to rump. The baby is taking up increasing room in your uterus, and continued growth will put pressure on your lungs, stomach, bladder, and kidneys.
Under the vernix caseosa (a protective, waxy coating), your baby's skin is thickening and developing layers. Hair and nail growth continue.
If you haven't already had one, your health care provider may recommend that you receive an ultrasound, a diagnostic test that uses sound waves to create an image. An ultrasound can determine the size and position of the fetus, and any structural abnormalities of bones and organs that are visible by this time. Depending on the position of the fetus, the sex can usually be determined by now. During an ultrasound, the umbilical cord, placenta, and amniotic fluid can also be examined. Talk to your health care provider about whether you should have this test.