Antenatal Screening & Counselling
Antenatal care includes regular medical visits, screening tests, and diagnostic tests to help assess your health status to keep you and your baby in a healthy condition during your pregnancy. The routine visits to the doctor are scheduled so that any problems present may be recognised and treated well in advance. These visits also educate you on handling various aspects of your pregnancy. Your doctor will discuss about healthy eating, activity, screening tests necessary and what can be expected during labour and delivery.
There are several antenatal tests to assess development of the baby in your womb. Antenatal tests are done at a stipulated time beginning from 8-10 weeks of gestation through 20 weeks. Prior to a test, counselling is done which will assist you in deciding the type of test based on advantages and disadvantages of each.
Antenatal screening tests such as ultrasound, first trimester and second trimester screening are done to determine whether your baby is at any risk of having a particular genetic condition such as Down's syndrome or other abnormalities. You should have antenatal screening done particularly if you have the following conditions:
- One of your near relatives or your previous child has a serious genetic anomaly
- If you or your partner are “carriers” of a faulty gene
- You are in your mid 30's or older
- Long term exposure to chemical or other harmful environmental agents
However, irrespective of your age or family history, it is always better to have the antenatal screening tests done.
First trimester screening: The first trimester screening is done between 11 weeks and 14 weeks of gestation and includes blood tests and an ultrasound examination. It is done to detect the risk of abnormalities such as Down's syndrome and trisomy 18. The blood tests determine the level of pregnancy-associated plasma protein-A and human chorionic gonadotropin in your blood. Nuchal translucency screening test, ultrasound examination, is done to measure the thickness of the back of the foetal neck. Large space or increased space indicates Down's syndrome, trisomy 18 or other chromosomal abnormalities. Your doctor may suggest for a more detailed examination at around 20 weeks of pregnancy, if first trimester screening tests are positive.
Second trimester screening: During this period, multiple marker screening is done to screen Down's syndrome, trisomy 18 and neural tube defects. The test measures the concentration of alpha-fetoprotein and hormones estriol, human chorionic gonadotopin, and inhibin-A in the mother's blood. These tests are done between 15 and 20 weeks of gestation.
Combined screening: The combined reports of the first and second trimester may yield more useful information about the diagnosis of Down's syndrome.
If the screening tests indicate a problem in the baby, further diagnostic tests such as detailed ultrasound, amniocentesis, and chorionic villus sampling and cordocentesis may be done to check whether the baby actually has a defect.
After the screening, if your baby is found to have an increased risk for developing a chromosomal abnormality or if a problem is detected with diagnostic testing, genetic counselling will support you with further decisions. Genetic counselling provides you the chance to discuss the following issues:
- Outcome of the results of antenatal tests
- Options available
- Further testing, its advantages and disadvantages
- Course of action that can be taken