By Sally J. Hall
NIPD and NIFTY scans – your window on the womb
B finds out all about the newest type of pregnancy testing and why it might be suitable for you.
You may have heard that there are new kinds of diagnostic pregnancy tests that are available to pregnant women that help them to discover that their baby is well and healthy. These are currently only available privately for around £500 and your doctor or hospital may offer this service as part of your ante-natal package. However, you might want to investigate this yourself and to find out the benefits of this kind of test.
Called NIPD (Non-invasive prenatal diagnosis) or NIPT (Non-invasive prenatal testing), the tests are conducted using a sample of the mother’s blood and are used to determine whether there is a chance of congenital conditions such as Down’s Syndrome.
This is a new and rapidly evolving technology and it is exciting because the tests carry far fewer risks for the baby than previous tests such as Amniocentesis and Chorionic Villus sampling (see What Came Before, below).
How does it work?
Non-invasive tests work by analysing DNA fragments that are contained in the mother’s blood plasma during her pregnancy, known as cell-free DNA. While the majority of this DNA is from the mother, approximately 10%-20% is from the placenta and shows the DNA make-up of your baby. This is called cell-free foetal DNA.
Scientists can detect Cell-free fetal DNA (cffDNA) from as early as your fourth or fifth week of pregnancy, though the levels are so low at that point that they are not reliable enough to give a clear picture of your baby’s genetics. Levels needed for testing for certain conditions are reached at different points of pregnancy.
What’s fascinating is that the cffDNA is unique to that pregnancy and it clears itself from the mother’s circulation within an hour after the birth.
NIPT is usually carried out in conjunction with an Ultrasound scan. This is to give you your due date and to find out if you are carrying one baby – or more!
What can it test for?
Non-invasive testing can detect a number of things:
- The baby’s sex. This is important in the case of conditions passed only to boys such as Duchenne muscular dystrophy and congenital adrenal hyperplasia (CAH).
- Rhesus Negative. If the baby’s blood type is Rhesus positive and the mother’s Rhesus negative, there is a serious risk to the baby of miscarriage. Women can, however, be successfully treated during pregnancy.
- Skeletal gene disorders such as achondroplasia, thanatophoric dysplasia and Apert syndrome.
- Down’s Syndrome or Down syndrome. This is perhaps the best-known of conditions, caused by the presence of an extra copy of chromosome number 21. These chromosomes seem to divide by accident and it is not caused by something the parents have or have not done during the pregnancy. It can affect one in every 1,000 babies in the UK and is more prevalent with older mothers. It causes physical differences, heart conditions and reduced hearing and vision though the extent to which the child is affected will vary greatly.
- Edwards syndrome
- Patau syndrome
What doesn’t it test for?
Physical and structural malformalities such as Spina Bifida cannot be picked up, nor heart defects. If your baby is not growing at the correct rate, this can’t be picked up either; however, further Ultrasound scans will find this. It can’t tell if an abnormal cell is from a particular baby in the case of multiple pregnancies either.
What are the benefits of non-invasive testing?
The use on a non-invasive test is a great benefit to many women, who have to put up with an awful lot of tests and examinations during pregnancy as it is. By having this kind of test, which can screen for more conditions plus your baby’s sex, it can cut down on having to have lots of other, more invasive tests. There is also no risk of miscarriage, as it is just a blood sample taken from the mother’s arm, which carries no risk to the baby. It’s also easier to access as a nurse or a phlebotomist can carry it out, rather than having to wait for an experiences surgeon to carry out Amniocentesis or Chorionic Villus sampling.
How long do results take?
The results of NIPT usually take about two weeks to process and the information will then be shared with you either in consultation with your doctor, or some companies will phone or email the results directly to you. You might want to think about how you prefer to hear the results – having the chance to talk through the results with your obstetrician is invaluable because you may not understand all the terms used.
Where can I find it?
There are now many clinics testing throughout the UK and your private hospital or clinic may either have the facilities to test for you, or will arrange for it to be done.
Commonly in the UK, the tests is called the Harmony Test, which can be done after the 10th week of pregnancy, or the Panorama test which is available after nine weeks. The latter is not suitable for twin or multiple pregnancies.
What Came Before
Before these non-invasive tests were developed, the only way for Obstetricians to determine your risk of having a baby with a genetic condition was to use invasive forms of testing. Amniocentesis is one of the best known and involves passing a tiny needle, guided by Ultrasound, into the space around the baby to collcet some of the amniotic fluid. This was then tested and your risk could be much more accurately decided. However, this test and Chorionic Villus sampling, which involves taking a sample from the placenta, usually via the cervix, carry the risk of miscarriage. Though small, it has meant that many women are unwilling to have Amniocentesis or Chorionic Villus sampling carried out, even if they think they are higher risk, as it might mean losing a much longer-for baby.
Non-invasive Prenatal Testing (NIPT)
Bryan BeattieConsultant in Fetal Medicine, Bryan Beattie, MD FRCOG, explains why women should consider these tests. “Pregnant women concerned about having a baby with Down’s or other chromosomal problems have to choose between the Combined Test (90% rate of detecting abnormalities), or amniocentesis, (100% detection rate) with a risk of miscarriage. This test, based on a maternal blood sample taken any time from 10 weeks of pregnancy extracts foetal DNA and then tests for the common chromosomal problems; Down’s, Edward’s, Patau and Turner Syndromes. It’s over 99% accurate and the chance of a false positive result (and needing to consider amniocentesis) is only one in a thousand. It works for twins and when IVF, ICSI or donor eggs or sperm have been used. They’re widely available in private clinics and cost about £450-550.”
Find your clinic at niftytest.com
Bryan continues, “The tests are appropriate for any pregnant woman who wants safe, accurate, reliable and early screening for conditions like Down’s Syndrome.” A useful comparison of some of the tests and some useful explanatory videos can be found at innermosthealthcare.com/NIPT.
Results and what they mean
“Think about the results of these tests and what they mean for you and your partner. If you’re concerned about abnormalities, perhaps due to your age or a genetic problem, you may want to know if your baby has health problems, particularly those that can be treated after or even before birth. If you would never consider termination, it’s needless to risk miscarriage with the CVS or Amnio. Counselling is available and you should make full use of it to weigh up what’s best. Discuss it with your partner.”