In this world, majority of new born babies are born normal. Only 3% to 4% new babies are born with birth defects.
The birth defects can be from severe or minor anatomic abnormalities to serious genetic disorder or sometimes it can be mental retardation.
Some couples possess greater risk of having a child with a birth defect. Genetic screening can help those couples to identify certain genetic disorders. But screening cannot identify all birth defects. Genetic screenings are suggested to those couples who have a family or medical history of certain genetic disease.
It is not possible to detect all types of birth defects before delivery but modern medicine has a provision to screen several defects. Extensive researches are going on to increase the number. Some other birth defects can occur due to toxic exposure in the environment or some other unknown cause. This type of defect is not possible to detect with genetic screening.
Before getting pregnant, doctors can screen the chances of several birth defects through blood test. Birth defects like cystic fibrosis, tay sachs disease and sickle cell anemia, and thalassemia are few of those. Even after a woman comes to know that she is pregnant, most of these tests can be conducted. Screening carried out during pregnancy can detect neural tube defects and Down’s syndrome.
Major defects of urinary tracts and digestive system can be screened by performing Ultra Sound. Pre-implantation genetic diagnosis (PGD) technique is used for vitro fertilization. Embryos are tested for genetic disorder before their transfer to uterus. PGD technique helps those couple who have a greater risk of passing any inherited disorder to their child. Presently PGD is not a very wide spread method. Very few institutions offer this diagnosis under strict supervision.
It is important to know that screening tests are conducted to identify the possible risk involved for a particular problem. Screening is not a complete diagnosis. Diagnostic tests can further verify whether the condition identified in the screening test is harmful or not.
To take an example, suppose a women is found positive during a screening test for Down’s syndrome, it is assumed that she possess the risk of Down’s syndrome. Still there are chances of baby being normal. Now she will need to undergo a diagnostic test, which will confirm whether the baby is affected or not. So, for final assessment, it is necessary to go for diagnostic tests.