On your first visit to the doctor for prenatal care, you'll undergo certain tests regardless of your age or genetic background.
Blood tests determine your blood type and Rh factor. If your blood is Rh positive and your partner's is Rh negative, you may develop antibodies that prove dangerous to your fetus. This can be treated through a course of injections. Blood tests also measure the level of iron in your blood and check for hepatitis B, syphilis, and HIV. You'll also be tested to see whether you're immune to rubella (German measles).
Urine tests check for kidney infections and signs of gestational diabetes and pregnancy-induced high blood pressure (which can cause a specific protein to show in the urine).
Cervical tests check for STDs (such as chlamydia and gonorrhea), cervical cancer, and Group B streptococcus infection. Group B streptococcus, which are bacteria that are not transmitted sexually, can cause serious infections in newborns.
Around the 16th to 18th week of pregnancy, most women will have a maternal blood screening test performed. Also known as a "triple-marker" test, it measures the levels of a protein produced by the fetus and two pregnancy-produced hormones in the mother's blood. This test can reveal the chances that a mother is carrying a fetus with neural tube defects or Down syndrome.
It's at this point that most women will also have their first ultrasound test, which helps the doctor identify the position of the baby and its gender as well as helping to detect Down syndrome, other chromosome abnormalities, structural defects such as spina bifida and anencephaly, and inherited metabolic disorders.
Around the 24th week of pregnancy, an additional screening for gestational diabetes may be performed.
Certain prenatal tests are considered routine - that is, almost all pregnant women receiving prenatal care get these tests. Others are recommended only for certain women, especially those who have what are known as high-risk pregnancies.
Non-Routine Prenatal tests:
Non-routine are generally recognized for women in the following catagories:
- are age 35 or older
- have had a premature baby
- have had a baby with a birth defect - especially heart or genetic problems
- have high blood pressure, diabetes, lupus, asthma, or a seizure disorder
- have or whose partner has an ethnic background where genetic disorders are common
- have or whose partner has a family history of mental retardation
Although your obstetrician may recommends these tests, ultimately it's up to the mother if she wants to have them. Your doctor should spend some time explaining the need for these tests. As a patient you need to be educated before you make your decisions.
In addition to talking to their obstetricians, women who have a family history of genetic problems in their families (or whose partners do) may want to consult with a genetic counselor who can help them construct a family tree going back as far as three generations.
To decide which tests are right for you, it's important to carefully discuss with your doctor what these tests are supposed to measure, how reliable they are, the potential risks, and your options and plans if the results indicate a disorder or defect.