The various screening and diagnostic tests done during the course of pregnancy play a crucial role in keeping track of the health of both mother and baby and possibly preventing illness and abnormalities in the baby.
First visit to gynaecologist and initial blood tests
Apart from confirmation of the pregnancy, a battery of blood tests is usually done at your first visit to the gynaecologist. The blood is tested for:
During each of your visits to the gynaecologist, the following tests/checks will be carried out:
Screening and testing for Down's syndrome and other abnormalities
Screening for Down's syndrome is usually done between the 11th and 14th week of the pregnancy. It initially involves a simple nuchal scan where the collection of fluid at the back of the baby's neck is measured during an ultrasound exam – a high reading could indicate Down's syndrome.
In case of a high reading, this scan could be followed by CVS (chorionic villus sampling) where a sample of cells that line the placenta is extracted, using a fine needle or a catheter, and analysed. The procedure carries a risk of miscarriage of 1%. Amniocentesis is probably the most accurate diagnostic test for Down's syndrome and involves the extraction of amniotic fluid from the uterus for analysis in a laboratory. Amniocentesis is ideally done between the 16th and 18th week of pregnancy and carries a low 1% risk of miscarriage.
The maternal serum triple test is a blood test that is also used to test for Down's, but it can also indicate neural tube defects such as spina bifida. It is a blood test that is done between the 15th and 22nd week of pregnancy. The test measures the levels of three hormones, so the correct dating of the test is crucial as incorrect dating can lead to incorrect interpretation of the hormone levels.
Murkoff, Heidi E & Eisenberg, Arlene & Hathaway, Sandee. 2002. What to Expect when you're expecting. Simon & Schuster