Your baby’s arms are nearly the length they will be on delivery day, which is impressive. The natural contour of your baby’s neck area is emerging while the spleen is diligently creating red blood cells. If the sex of your baby is not obvious at this time on an ultrasound there’s no need to worry because it will be in the very near future. For fun, you can ask for a perfect profile shot and use the “Angle of the Dangle” concept. Ovarian follicles are now developing and moving from the abdominal area into the pelvic area in girls, while the prostate is developing and becoming visible in the boys.
Your baby’s tiny thyroid is now busy producing essential hormones. The growth of the roof of the mouth (palate) is now finished. Body hair called lanugo will begin covering your baby, but will usually vanish by birth. Although the precise purpose of lanugo is a mystery, it is thought that it may provide your baby with warmth until fat accrues. Another possibility is that it holds in place the polished coating, vernix caseosa, which will envelop your baby’s body around Week 19.
By the time your baby’s birthday arrives, his or her head will have quadrupled the present size. Now nearly 3½ inches long, about the size of a large McIntosh apple, your baby weighs about 1½ ounces.
The Quad Marker Screen is a blood test that is performed between Weeks 15-20 of your pregnancy. This screen determines if you are at a higher or lower risk of carrying a baby with a birth defect such as Down syndrome, Open Neural Tube Defects (NTDs) including spina bifida, or Trisomy 18. This test predicts the likelihood of several potential problems with your baby and/or carrying your baby; it does not diagnose the problem.
The Quad Marker Screen measures multiple biochemical markers in the mother’s blood that are produced by the fetus and placenta during the early second trimester. A positive screen does not provide a diagnosis, but indicates the increased risk and the need for further evaluation. It is followed by an ultrasound, which may be your Week 20 ultrasound. Speak with your health care team to decide if you should consider having the Quad Marker Screen performed.