Screening for Down Syndrome and Major Chromosomal Disorders


Down Syndrome occurs if a baby has three copies of its 21st chromosome instead of two copies. A chromosome is a bundle of genetic material, and if you have too many or too few of these bundles, severe abnormalities can result. In the case of Down Syndrome, these abnormalities include intellectual, heart, thyroid and other endocrine, facial appearance and others.
It is possible to detect early in the pregnancy whether your baby might be at high risk of having Down Syndrome. This is possible through consideration of your age and additional tests.

The additional tests are Combined First Trimester Screening and Non-invasive Prenatal Testing (NIPT).
It is important to realise that both of these tests are considered to be “screening test”. This means they won’t tell you “yes, your baby has Down syndrome” or “no, it definitely does not have Down syndrome”. They will, however, say if your baby is at high risk of having Down syndrome, in which case you should have a diagnostic test. A diagnostic test is one that will tell you “yes” or “no”.
Combined First Trimester Screening requires a blood test at 10 weeks and an ultrasound between 12 and 13 weeks. Most patients choose this option. The blood test costs about $120 (no medicare rebate) and a specialised ultrasound costs about $150 after the medicare rebate, however this varies from clinic to clinic. Combined First Trimester Screening screens for Down syndrome and Trisomy 18. The detection rate for Down syndrome is 90%.

NIPT is no doubt the future of prenatal testing for Down Syndrome and other genetic abnormalities due to its incredible accuracy and lack of risk to the baby. It uses a maternal blood sample to find and test the baby’s cfDNA(cell free DNA – genetic material) in the mother’s bloodstream. Costs are constantly falling, but it is quite expensive costing about $550 and no rebate applies. This non-invasive prenatal test (NIPT) is safe and poses no risk to mother or baby. It’s recommended that expectant parents discuss with their health practitioner the limitations and advantages of cfDNA screening before having the test.
Most women would still opt for a 12 week ultrasound if doing NIPT; whilst the ultrasound has no impact on the Down Syndrome result when doing NIPT, it does provide other useful information about the development of the baby; so a saving is often not made by omitting the ultrasound.
Lenore will discuss these options with you in detail at your first pregnancy appointment.

Genetic Screening

It is now possible to check if your baby has a chance of inheriting genetic conditions. The conditions that testing is currently available for is cystic fibrosis, spinal muscular atrophy, and fragile X syndrome.
It costs about $350 per person tested for all three conditions. It is usual to test the mother or the father first, then arrange testing for the partner if a copy of the gene is found, so there is potential that both parents would need the test.

Are immunisations necessary and are they safe?

Some infections can cause serious harm for both the pregnant woman and her unborn baby.

Prior to pregnancy

  • Rubella and Varicella (Chicken pox virus)
  • Booster immunisation is advised before becoming pregnant to those with no/low immunity

During pregnancy

  • Influenza (Flu, Swine Flu)
    • Flu is particularly serious for pregnant women and their babies- both unborn and newborn. Flu vaccination is strongly advised if you are going to be pregnant during the flu season (March –October). The seasonal flu vaccine covers both seasonal flu and swine flu. It is SAFE and EFFECTIVE.
  • Pertussis (Whooping cough)
    • This is a serious infection that mainly affects very young babies. Adult immunity from childhood generally wanes over time. If infected, these adults usually have a mild form of the disease but may pass on the infection to young babies. As such, booster immunisation to whooping cough is recommended for all adults who are going to be in close contact with young babies.

Therefore, I highly recommend the following actions to reduce the possibility of infection in these most vulnerable young infants.

  • ALL adults who will be in close contact with the newborn baby should have a Whooping cough booster (Boostrix) if they have not had one in the last 10 yrs. This can occur at ANY TIME.
  • Pregnant patients should have a Whooping Cough booster between 28-34 weeks to maximise the transfer of protective antibodies to the fetus.
  • Recommended in ALL pregnancies, irrespective of when last Boostrix vaccine was administered.
  • Vaccinate young infants as per the National Immunisation Schedule at 2, 4 and 6 months.
  • The vaccine is currently free for parent