Throughout your pregnancy, there will be many tests and procedures you will take to check your health, such as a pregnancy test home kit or a blood test to confirm that you are expecting, a glucose test to monitor your blood sugar, etc. There are also genetic tests that could tell you about your unborn baby's health.
Some of these tests are routine while some are recommended by doctors only if they see the need, after factoring in the mother's age and medical family history. In other instances, it's up to the parents if they want the tests done. According to the American Congress of Obstetricians and Gynecologists (ACOG), screening tests only determine the chances of your baby having an abnormality, and thus, would require diagnostic tests that give more definite answers.
In the U.S., approximately one in four babies are born with a health condition, which is why some parents fear the results even if these only present the likelihood of the baby developing these conditions. Still, many parents have these screening and diagnostic tests done for peace of mind. Here are the most common tests to check on your unborn baby's health:
Nuchal translucency (NT) scan This is a non-invasive early screening test for Down Syndrome which uses ultrasound and a special instrument, nuchal translucency, to measure the space in the tissue at the back of the unborn baby's neck. According to Baby Center, babies with abnormalities tend to accumulate more fluid at the back of their neck during the first trimester. The test is done between the 11th and 14th week of pregnancy, and there's a 10- to 20-percent that a scan may not detect any risk at all. About five percent of the babies who test positive for Down syndrome via this scan could be born perfectly healthy.
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Maternal serum triple test This non-invasive screening test is done with a routine blood extraction from the mother, then checking the sample for human chorionic gonadotropin (hCG) and pregnancy-associated plasma protein (PAPP-A). Very high levels of these two may mean your baby could have increased chances of having Down syndrome. The Centre for Genetics Education finds that about 60 percent of babies who have Down syndrome will be predicted by this scan while 40 percent of babies could be overlooked by this test. However, it can identify almost 95 percent of babies who have spinal problems or neural tube defects. The test is done between the 11th and 14th week, and is usually done simultaneously with an NT scan for improved accuracy in the results.
Non-Invasive Prenatal Testing (NIPT) Sometimes done with a NT scan, this is another non-invasive screening test a pregnant woman can take to check for chromosomal abnormalities early into the pregnancy. It involves routine blood extraction from the pregnant woman and uses cell-free fetal DNA to check for chromosomal conditions such as Trisomy 21, Trisomy 18, Trisomy 13, and a few other conditions as early as the 10th week of pregnancy. It has an above 92-percent accuracy, but as it is a screening test, it still does not guarantee that a baby who tested positive will be born with the congenital anomaly. Usually, if the tests come back positive, doctors would recommend diagnostic tests to confirm diagnosis.
Quad Screen Doctors usually recommend having this screening test done during the second trimester of pregnancy, between week 14 and week 22. It's called a Quad Screen because it uses four indicators -- Alpha-fetoprotein (AFP), a protein made by the baby; human chorionic gonadotropin (hCG); estriol, a form of estrogen produced by the placenta and baby; and Inhibin A, a hormone made by the placenta -- to check for neural tube defects and chromosomal abnormalities. High levels of AFP may suggest a possibility of a kind of neural tube defect present in the baby, while low AFP numbers and abnormal levels of the other three may suggest chromosomal abnormalities. It's less accurate than the NIPT, but is more affordable.
Amniocentesis Done around the 15 to 18th week of pregnancy, it's a diagnostic procedure where doctors take a sample of the amniotic fluid, or the pool of liquid where your unborn baby swims in inside your womb. Similar to the placenta, this fluid contains cells from the baby which are tested for some types of birth defects such as infections, spina bifida, and other genetic conditions. Some women experience cramping and spotting or leakage of the amniotic fluid after the 30-minute procedure, and there is also a 0.5-percent risk for miscarriage.
An amniocentesis could detect nearly all chromosomal disorders including Down syndrome, Trisomy 13, Trisomy 18, and sex chromosomal abnormalities, but it can't tell the severity of the condition. It can also detect cystic fibrosis, Tay-Sachs disease (a rare genetic disorder that affects the brain and spinal cord), and blood disorders such as sickle-cell anemia and thassalemia, and neural tube defects such as spina bifida and anencephaly.
However, an amniocentesis cannot detect physical birth defects such as heart malformations, or a cleft lip or palate. These can be found out via a routine ultrasound scan and other prenatal tests.
Chorionic villus sampling (CVS) This diagnostic test is usually done between the 11th and 13th week of pregnancy. With the help of an ultrasound, a thin needle is inserted into the pregnant woman's cervix or through her abdomen to take a sample of the placenta. The placenta develops with the embryo and contains genetic samples from the baby that could indicate chromosomal problems. Pregnant women will be advised to rest . Cramping and vaginal bleeding are some of its common side effects, which is why pregnant women are advised to rest for the remainder of the day after the procedure. It is generally safe, though there is a 0.5 to one-percent risk for miscarriage.
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Like an amniocentesis, it could detect almost all chromosomal defects and genetic disorders mentioned above. It cannot, however, detect neural tube defects such as spina bifida, which can be checked via a routine ultrasound.