A Serum Screen, sometimes called a Triple Screen blood test may be offered to you between 15 and 20 weeks of pregnancy, regardless of your age or pregnancy risk. A tube of your blood is drawn and three values are measured: AFP, maternal serum alpha-fetoprotein; HCG, human chorionic gonadotropin or pregnancy hormone; and unconjugated estriol. Your risk of carrying a baby with a neural tube or abdominal wall defect, Down syndrome, or Trisomy 18 is estimated from these levels in conjunction with your age. This is not a firm diagnosis, but does let your provider know that you may need further testing. It’s important to keep in mind that a questionable Triple Screen result does not necessarily indicate a problem with your baby.

Your baby's heartbeat can usually be heard after 10 - 12 weeks, and sometimes even earlier using a small, handheld sound amplifier called a Doptone. A Doptone lets you listen to your baby's heart rate at the same time that your provider does. Another tool that your provider can use is called a fetoscope, which is an odd-looking stethoscope your provider wears on his forehead. Unfortunately it doesn't let you listen along with your provider. The Doptone and the fetoscope cannot hurt your baby; and they can both reassure you and your provider that your baby's heart is beating properly.

Your provider will check to see how much your uterus has grown at each of your prenatal visits. Your uterus grows from the size of a pear to that of a basketball during your pregnancy. By the end of the first trimester, your provider can feel your uterus just above your pubic bone by doing a pelvic exam. By 20 weeks into your pregnancy, your uterus typically reaches your belly button.

After that, it should grow 1 centimeter every week. During the second half of pregnancy, your provider will generally use a tape measure, stretched across your abdomen to check the height of your uterus. If there is more than a 3-4 centimeter discrepancy from what is expected, your provider will do an ultrasound to measure your baby.

Many pregnant women have an ultrasound when they are 16 to 20 weeks pregnant. An ultrasound uses sound waves that bounce off of your baby and makes a picture based on those waves. This test is safe for both you and the baby, and it helps your provider to check the health and development of your baby.

It's also your first chance to "see" your baby. Although the picture is not clear like a photograph, you can usually see your baby's head, body, arms and legs, and her beating heart! Sometimes you can even see things like little hands, feet and eyes. Of course, your provider will probably have to point these out to you, since they're usually pretty blurred.

A Serum Screen, sometimes called a Triple Screen blood test may be offered to you between 15 and 20 weeks of pregnancy, regardless of your age or pregnancy risk. A tube of your blood is drawn and three values are measured: AFP, maternal serum alpha-fetoprotein; HCG, human chorionic gonadotropin or pregnancy hormone; and unconjugated estriol. Your risk of carrying a baby with a neural tube or abdominal wall defect, Down syndrome, or Trisomy 18 is estimated from these levels in conjunction with your age. This is not a firm diagnosis, but does let your provider know that you may need further testing. It’s important to keep in mind that a questionable Triple Screen result does not necessarily indicate a problem with your baby.

Elevated AFP detects approximately 85% of babies with open neural tube defects, or “spina bifida”. The test is not perfect, meaning that yours could be falsely negative and not detect an abnormality present. On the other hand, there's a 3 - 4 % chance that your test could be falsely positive and make you worry even though your baby has no birth defect. If your AFP is abnormal, you will have an ultrasound done to confirm that you are as far along in your pregnancy as you thought, based on your last menstrual period. Many false positives are due to incorrect dating of the pregnancy. Other women might be carrying twins or may have suffered a pregnancy loss without being aware of it. Others are carrying babies with a normally formed brain and spinal column but a birth defect in the abdominal wall or kidneys. If your baby's ultrasound is normal and the test result is unexplained, you'll be offered an amniocentesis to directly assess the genetic information from the amniotic fluid around your baby. An amniocentesis result is both more sensitive and more accurate than the blood test, although the test does carry a small risk of miscarriage.

Rhogam administration applies to you only if your blood type is negative. Fifteen percent of Caucasians, 5-8% of African Americans, and 1-2% of Asians and Native Americans are Rh-negative, meaning that they lack a particular molecule on the outside of their red blood cells.

If a woman is carrying a baby who is Rh-positive, like their father, and the woman is Rh-negative, she can react to the baby’s cells. Without knowing the father's blood type, an Rh-negative woman has about a 60% chance of bearing an Rh-positive baby, but less than a 12% chance of becoming sensitized.

Sensitization involves a woman's body making antibodies against what it perceives as foreign, in this case, sugar molecules on the outside of her growing baby's red blood cells. These antibodies can destroy your baby's red blood cells or cause a miscarriage due to severe fetal anemia. These antibodies can also cause problems with future pregnancies.

Rhogam is Rh-immune globulin and is administered as a shot like a vaccine. It prevents most Rh-negative women from developing antibodies to their baby's Rh-positive red blood cells.

If the father of your baby is Rh-negative, you do not need Rhogam at 28 weeks. If you are Rh-negative and the father of your baby is Rh-positive, you must receive Rhogam to protect your future pregnancies. The shot is given at around 28 weeks, and again after your delivery IF your baby is Rh-positive.