What is prenatal test?

Prenatal tests are needed to assess the health of the mother and her baby during the pregnancy and to detect abnormalities and complications at an early stage.

Is there any screening test that I can do to assess the risk of chromosomal abnormalities?Yes, currently there are two different test available in town. First Trimester Screening and Second Trimester Screening (Triple test). The different in this two test are performed at two different trimester. 

What is the First Trimester Screening?

What are the advantages of First Trimester screening?

First-trimester screening lets you learn about your baby’s risk for chromosomal problems relatively early in the pregnancy without subjecting yourself to the slight risk of miscarriage from an invasive test like CVS.

If the risk is low, the results will offer you some reassurance. If the risk is high, you may have the opportunity to consider CVS (Chorionic Villous Sampling) or amniocentesis diagnostic test, which will reveal whether your baby has a problem while you’re still in your first trimester. The sensitivity of this test is about 92%.

How is the First Trimester Screening done?

First Trimester Screening test is a combination of a blood test and the ultrasound scan. The blood which drawn from the arm will use to measure the level of two hormones normally found in pregnant woman; free beta-subunit of human chorionic Gonadotrophin (free B-hCG) and Pregnancy Associated Plasma Protein-A (PAPP-A). From the ultrasound scanning, the Nuchal Translucency (fluid-filled space beneath the skin behind the neck ) marker will be measured. This combination tests is need for the screening of the three most common fetal chromosomal abnormalities, namely, Trisomy 21(Down’s Syndrome), Trisomy 18(Edward’s Syndrome), and Trisomy 13(Patau’s Syndrome).

What is the Triple Test Screening?

For those who miss the First trimester screening can consider Second Trimester Screening (STS or Triple test). It is a blood test of free beta HCG, unconjugated Estriol and Alpha Fetal Protein. The sensitivity of this test is 60-70%.

A high risk result does not mean that your baby has Down’s Syndrome or any genetic abnormalities. But, it gives you information that there is an increased risk of your baby being affected. Your doctor will probably want you to have a diagnostic test.

The diagnostic tests in the prenatal period are specialized tests such as amniocentesis, chorionic villous sampling (CVS) and foetal blood sampling (FBS) which are able to detect foetal abnormalities especially chromosomal abnormalities such as Down’s Syndrome.

Screening tests are non-invasive, therefore does not pose any dangers to the foetus, screening can give a risk assessment. On the other hand, Diagnostic tests are invasive, there is a risk of miscarriage, However, it will give you a definite answer of whether your baby is affected.

Any age will have the risk of having Down’s syndrome baby although 35 years and above have a higher risk.

If women above age of 35 has higher risk of having a Down’s Syndrome baby, why is it 80% of Down Syndrome babies are born to women under the age of 35?

It Is because the age group think that they have lower risk and hence did not perform screening test.