Non-invasive prenatal testing: tips for choosing
When expecting a child, many decisions need to be made about the health of mother and unborn child. In addition to leading a healthy and balanced lifestyle, it is essential to undergo non-invasive or invasive prenatal examinations and tests (such as amniocentesis).
Gynecology experts recommend routine exams to check how the pregnancy is progressing. Non-invasive prenatal screening tests let you know your baby’s health as early as the first weeks of pregnancy. It is not easy for parents to choose among all the types of screening tests there are the one best suited to their needs, which is why it is important to pay attention to several aspects.
Meanwhile, it is good to assess how far in advance you want to know the health of the baby. Among the first feasible tests (as early as week 10) is fetal DNA testing. The Bi Test in combination with nuchal translucency can be done from the 11th to 13th weeks, and the Tri Test between the 15th and 17th.
It is necessary to evaluate the reliability rate when choosing the screening test. The rate is calculated on the percentage of abnormal outcomes actually detected (ex. Trisomy 21) and the rate of false positives (outcomes according to which there’s an abnormality that is not actually present). Bi Test and nuchal translucency are 85% 1 reliable with a 5% false positive rate.
Tri Test is 60 percent reliable and returns false positives of up to 8 percent. Prenatal fetal DNA testing is 99.9% reliable 2 (in detecting major trisomies in the fetus), and returns 0.3% false positives.
These tests are referred to as “prenatal screening” and return the probability that there are chromosomal abnormalities in the fetus. If the result is positive or not entirely clear, investigations should be made through invasive prenatal diagnostic tests. Here, then, the choice of the most suitable prenatal test for one’s needs is important to reduce the likelihood of having to undergo even invasive tests (such as amniocentesis and villocentesis), and to have reliable outcomes.
OB/GYN will be able to advise on the most appropriate prenatal test.