Chromosome abnormalities in infants who are still in the womb are rare. However, many parents are worried that their baby will be affected. A chromosomal abnormality detection test in infants can help parents prepare for proper early treatment.
Although you always take care of your pregnancy so that the prospective baby grows healthy, but there are some things that can happen to your pregnancy. One of them is chromosomal abnormalities that may cause certain diseases, such as Down syndrome.
What are chromosomal abnormalities?
Chromosomes are structures that contain elements of human genetics. Humans have a total of 46 chromosomes, two of which are sex chromosomes, called X and Y. The composition of chromosomes for women is 46 XX, while for men is 46XY. Every half of a pair of chromosomes, inherited from each parent.
Chromosomal abnormalities have also caused at least 50 percent of miscarriages in early pregnancy. One of the most known chromosomal abnormalities is Down syndrome, because it has 47 chromosomes. Down syndrome causes a person experiencing it to have a low IQ and different physical conditions, such as short legs, and distinctive wrinkles around the eyes, congenital heart defects are also common and can appear at birth.
Therefore, it is important to check pregnancy early on with a series of certain tests that can help detect chromosomal abnormalities, including:
Early Examination Test or Screening
A diagnostic test that is preceded by an initial examination can generally be done at 11-20 weeks’ gestation. By knowing the likelihood of chromosomal abnormalities in the baby to be born, this test will give you time to prepare for the birth of a baby with special needs.
A diagnostic or screening test that pregnant women can do is an ultrasound examination, blood test, or a combination of both. Ultrasound or ultrasound examination can detect physical abnormalities, such as spina bifida. While blood tests can help find the risk of congenital abnormalities, such as sickle cell anemia. The combination of the two tests can help find the risk of chromosomal abnormalities, such as Down’s syndrome and Jacob’s syndrome.
After the initial examination, there are several alternative diagnostic tests to determine whether the baby has the potential for certain abnormalities, including:
Amniocentesis is an examination of a baby’s chromosome abnormalities by taking a sample of amniotic fluid. Examination conducted at around 16-20 weeks of pregnancy has a 99 percent accuracy rate in detecting almost all types of chromosomal abnormalities, such as Down syndrome and Turner syndrome. By detecting alpha-fetoprotein (AFP) levels in the amniotic fluid, it can also be known the presence of neural tube defects in infants. Amniocentesis, which is carried out in the second trimester, carries a small risk of miscarriage, which is around 0.6%. This risk will be higher if amniocentesis is done before 15 weeks of pregnancy (first trimester).
- Chorionic villus sampling (CVS) Chorionic villus is part of the placenta where there is a border between the maternal and fetal blood vessel tissue. The genetic composition of chorionic villus cells is the same as the genetic composition of fetal cells. CVS is a test that can find certain problems in your fetus, this includes diseases in genetic disorders and chromosomal abnormalities. Usually, this test is done early in pregnancy, i.e. the 10th and 12th weeks. CVS is done by taking chorionic villus cell samples that are identical to baby cells through a special needle. This procedure is carried out with the help of ultrasound with the procedure. This test usually provides faster results, giving you more time to make decisions about pregnancy or your plans for the future. CVS carries the risk of miscarriage, which is the loss of pregnancy in the first 23 weeks. The risk of miscarriage is estimated at around 1% to 2%.
- Fetal blood sampling (FBS) Test to detect chromosomal or genetic abnormalities is done by taking baby blood samples directly from the umbilical cord or fetus. FBS is also performed to check the presence of infection in the fetus, anemia, and fetal blood oxygen levels.
The above investigations generally have 0.5-2 percent chance of miscarriage. Therefore, these tests are only recommended for high-risk pregnant women, namely those who previously had children with chromosomal abnormalities or genetic disorders, pregnant women aged 35 years and over, and women who have a history of family members with congenital abnormalities.
In addition to the above examination, there is one type of screening examination that is noninvasive and safer with ultrasound namely the nuchal translucency examination. This examination can not confirm the diagnosis as in the genetic examination above, but can determine whether the fetus is at high risk of suffering from Down syndrome or not.
Types of Common Disorders in Infants
Chromosomal abnormalities can cause specific disorders experienced by babies. There are various types of these disorders. The following are some of the most common diseases that can be detected by the tests above, including:
Abnormalities in the number of chromosomes that cause learning disabilities and differences in the physical appearance of humans in general.
Abnormalities in the development of the spinal cord and spinal cord resulting in gaps in the spine, as well as disorders of the brain. This disorder can be caused by a lack of folic acid intake in pregnant women, a family history of similar diseases, and due to the use of certain drugs during pregnancy.
Blood disorders are hereditary that cause red blood cells to not function normally, resulting in anemia.
In some conditions such as thalassemia, babies will experience abnormalities if there is a gene mutation obtained from both parents.
There is no treatment for chromosomal abnormalities. If a congenital abnormality is made before the birth of the baby, parents need to get an explanation from the doctor and consider carefully to determine the next step.