The provider will likely perform some standard tests during the first visits. These tests often include a complete blood count to look for anemia, an evaluation of one’s blood type, and tests for syphilis, hepatitis B and immunity to rubella. If the expectant mother has not had a recent pap smear, the provider may perform one during the pregnancy. Other tests that are not routine, but which are commonly performed, include tests for gonorrhea, chlamydia, sickle cell disease and toxoplasmosis. Pregnant women are at a higher risk for urinary tract infections (bladder infections or UTIs) and for the spread of these infections to their kidneys (pyelonephritis). For this reason, a urine culture may be performed to ensure that there is no UTI.
HIV (Human Immunodeficiency Virus) testing is not mandatory, but the HIV test and counseling should be offered to all pregnant patients. Medications can be given during pregnancy which significantly decrease the risk of HIV being passed from an HIV-infected mother to her newborn child. Any questions regarding the mother’s risk of having HIV or about HIV testing should be addressed with the provider.
The provider may want the expectant mother to see a genetic counselor. Several types of birth defects can be passed from generation to generation. The genetic counselor can help her determine if she is at high risk for passing along a genetic disease such as hemophilia, cystic fibrosis, muscular dystrophy, sickle cell disease, and many others. Genetic counselors may encourage some couples to seek diagnostic testing of the baby’s chromosomes.
Because the risk of having a chromosomal abnormality increases as the mother’s age increases, testing of the baby’s chromosomes is routinely offered to women over the age of 35. For women under the age of 35, there is a recently developed test, called the multiple marker screen (MMS), which identifies women who may be at higher risk for having a baby with chromosomal problems including Down’s syndrome (trisomy 21). The MMS is performed about 15 to 18 weeks into the pregnancy using the mother’s blood and, therefore, does not adversely affect the fetus. However, if the MMS identifies the mother to be at a higher risk for a chromosomal problem, she will be given an amniocentesis to make the diagnosis. One of the markers in the MMS is a substance called alphafetoprotein, or AFP. Elevations in AFP are associated with neural tube defects which are malformations of the baby’s spine or skull. If the mother’s AFP levels are elevated, an ultrasound is performed to confirm the age of the baby and amniocentesis offered to verify the elevated AFP levels.
There are a couple of techniques used to obtain cells from the baby. The most common techniques are chorionic villous sampling (CVS) and amniocentesis. CVS can be performed from the ninth to the 12th week of pregnancy and involves taking a small piece of placental tissue.
Amniocentesis is usually performed after 15 weeks and involves inserting a small needle into the uterus and drawing out some of the amniotic fluid surrounding the baby. The cells obtained from CVS and amniocentesis are sent to a special laboratory where the chromosomes are evaluated.
Ultrasound examination of the baby is commonly performed throughout pregnancy. Ultrasound is painless and safe for the developing fetus as it uses the energy from sound waves to make its images. Early in pregnancy, it may be used to verify the age of the fetus, the number of fetuses, and the location of the pregnancy if an ectopic or tubal pregnancy is suspected. At about 18 to 22 weeks of pregnancy, the ultrasound produces a detailed picture of the developing baby’s anatomy. Later in pregnancy, the ultrasound may be used to evaluate the growth of the baby, the amount of amniotic fluid, and the location of the placenta.