Last updated on Feb 17th, 2021 at 03:53 pm

Prenatal tests are one of the many ways of checking the well-being of you and your unborn baby. These tests are widely used for women at risk of having babies with chromosomal disorders like Down syndrome. A recent study published in the Journal of the Medical Association found evidence that prenatal tests can detect cancers in pregnant women. Read the study here.

Are you uncertain about what to expect at routine check-ups during your pregnancy? Here’s all you need to know about which tests are done when and why:


FIRST TRIMESTER

  • A urine screen for sugar and protein will be performed at each of your routine visits to your gynaecologist. The purpose of the test is to identify any signs of gestational diabetes, pre-eclampsia or kidney and bladder infections.
  • A haemoglobin test is performed early during the first trimester to check for anaemia, and it’s repeated in the third trimester.
  • An antibody screen is done during the first trimester and then again at week 28 of the pregnancy to check for potential blood-type incompatibility of the mom and the foetus, for example, Rh-positive/negative, and therefore any risk of developing antibodies that may affect the pregnancy.
  • A combined maternal blood screening test and an ultrasound evaluation of the foetus is done between week 11 and 13 of the pregnancy. The purpose of this test is to determine whether or not the foetus is at risk of chromosomal abnormalities such as Down’s syndrome and Trisomy-18. These tests are often regarded as an additional aid since a sonar scan can’t detect foetal abnormalities. Older women are the major beneficiaries of these screening tests, as the risk of carrying a Down’s syndrome baby increases with age.
  • Two pregnancy-related hormones, hCG and PAPP-A, are measured during the blood screen test.  If these hormone levels increase, then there’s a subsequent increase in the risk of the foetus having Down’s syndrome. The reason for the ultrasound evaluation is to measure the nuchal translucency (the fluid beneath the skin behind Baby’s neck), which can help to identify other foetal abnormalities such as cardiac disorders. The results of the blood tests and the ultrasound are then combined with the mother’s age to determine whether the foetus is at risk of any abnormalities. If anything unusual is picked up during these tests, it doesn’t necessarily mean that the foetus has an abnormality; it simply shows that a mother is at risk of carrying a baby with a genetic disorder and that further testing is necessary.
  • A Chorionic villus sampling may be recommended if the maternal blood screening test shows abnormal results. This test is done during the 12th week of the pregnancy and is used to determine if the foetus has any chromosomal abnormalities.

SECOND TRIMESTER

  • An Alpha-Foetal Protein (AFP) or Serum Triple Test, an ultrasound or sonogram, an amniocentesis and a glucose tolerance test are commonly done during the second trimester of pregnancy.
  • The maternal serum triple test consists of an Alpha-fetoprotein (AFP) test, a Human chorionic gonadotropin (hCG) test and an Unconjugated estriol (uEST) test. “The test is done between 16 and 20 weeks of pregnancy and assists in identifying whether the foetus is at risk of Down’s syndrome, chromosomal abnormalities such as neural tube defects, spina bifida and Trisomy–18.
  • If any of the above-mentioned test results are abnormal, further testing, such as an amniocentesis, will be necessary.  An amniocentesis is quite an invasive diagnostic test, which is done to determine whether the foetus has any birth defects or chromosomal abnormalities. This test is usually only performed on women whose Serum Triple Test showed abnormal results and who are thought to be at risk of carrying a baby with a genetic disorder.
  • A routine anatomy scan of the foetus is done between 20 and 24 weeks of pregnancy. The ultrasound allows you to see most of your baby’s physical features, and it may also determine the foetal position, size, and quantity of amniotic fluid, as well as the location of the placenta and sometimes the gender of the baby, although this is not always 100% correct. Genetic disorders such as a cleft lip, spina bifida, cardiac disorders, club feet and Down’s syndrome can also be detected during this scan.
  • A glucose tolerance test is routinely done between 24 and 28 weeks of pregnancy and is used to screen for gestational diabetes in mothers.

THIRD TRIMESTER

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  • Platelets are important for blood clotting if there’s bleeding during the birthing process, which is why a platelet count is done to identify if there’s a low count or possible other platelet problems.
  • An amniocentesis is also done after 32 weeks if women are at risk of a pre-term delivery. This is done to determine whether the baby’s lungs are developed efficiently for survival after a pre-term birth at this stage.

The majority of the above-mentioned tests are done routinely, but there are a couple that will require your permission if your doctor recommends that you have them, and if they’re needed. The private sector may also offer more tests for routine pregnancy check-ups than the public health sector, so take note of the above information so that you are aware of which tests to expect.