Non-Invasive Prenatal Testing (NIPT)
Introduction
NIPT analyzes cell-free fetal DNA circulating in maternal blood. It is obtained from a simple blood draw. It is a relatively new technology in prenatal screening and testing for trisomy 21 and other fetal chromosomal aneuploidies. It differs from the California State-sponsored Prenatal Screening program in the following ways:
| NIPT | CA Prenatal Screening | |
| Cost | Cost is based on your insurance; out of pocket max, $200 | Free with most insurances |
| Tests | The most common chromosomal disorders only: Down Syndrome (Trisomy 21) trisomy 18 & 13. Can also tell if your baby is a boy or a girl. More advanced testing also available. | Screening for chromosomal AND “mid-line defect” issues (spina bifida, Open Neural Tube Defects, gastroschesis) |
| Accuracy | 97-99% Sensitive and Specific (almost diagnostic) | Accuracy varies: up to 90% accurate for Down Syndrome, 80% for ONTDs |
| Timing | Can be done any time in the pregnancy from 10 weeks. | Done at particular intervals; Final results available after 16 weeks |
NIPT Test Characteristics
Genetic testing using cell-free fetal DNA
DNA from the fetus circulates in maternal blood. Unlike intact fetal cells in maternal blood, which can persist for years after a pregnancy, circulating cell-free fetal DNA (ccffDNA) results from the breakdown of fetal cells (mostly placental) and clears from the maternal system within hours. Fetal DNA detected during a pregnancy, therefore, represents DNA from the current fetus. Although only about 10-15% of the cell-free DNA circulating in maternal blood is from the fetus, it can be detected and measured. Quantitative differences in chromosome fragments in maternal blood can be used to distinguish fetuses affected with trisomy 21, and a few other fetal aneuplodies, from those that are not affected.
NIPT is currently offered by a host of companies:
We like NIPT because it offers families early testing for genetic diseases that can affect their choices in pregnancy- like early follow up care, education about place of birth, or opportunities to consider further testing. The drawback with NIPT is that it does not test for “mid-line” defects which could also impact a family’s choices. So we’re very careful when counselling our families about the wise use of this new emerging technology. People DO love to find out early if it is a boy or a girl. We enjoy their reactions, too.
