A 34-year-old healthy pregnant woman underwent serological screening at 18 weeks of gestation, the results of which indicated a low risk (risk value: 1:3900) so she and her family were awaiting a healthy baby. However, considering her advanced maternal age, the doctor advised her to adopt NIPT for a healthy fetus. After informed consent, she and her family decided to conduct NIPT at 20 weeks and 2 days of pregnancy. Surprisingly, the results showed that the fetus had a high risk of trisomy-21. The results of karyotype analysis were 47, XN, +21, suggesting that the child had trisomy-21 syndrome. After consideration, she finally chose to terminate the pregnancy to avoid the baby with trisomy-21 syndrome.
Noninvasive Prenatal Testing
There are more than 900,000 birth defects in China every year, and the total incidence of birth defects is about 5.6%, among which, Down's syndrome (trisomy 21), Edward's syndrome (trisomy 18) and patau's syndrome (trisomy 13) accounted for 80~90% of all birth defects.
NIPT is a prenatal screening designed to test the free fetal DNA in pregnant women’s peripheral blood and evaluate the risk of aneuploidy (Trisomy 21, Trisomy 18, Trisomy 13 etc.), It works by examining the small fragments of DNA – known as cell free DNA (cfDNA)-floating in the mother’s blood. Most of these fragments will be from mother, but a proportion will come from the placenta and therefore carry the DNA of the fetus. Analyzing cfDNA from the placenta provides an opportunity for early detection of certain genetic abnormalities without harming the fetus.
Who benefits from NIPT?
Pregnant women concerned about the health of their fetuses
Pregnant women who don't want to do amniocentesis
Serological screening suggests a high risk of pregnancy
Serological screening high-risk pregnant women
Patients with interventional prenatal diagnosis contraindications
Pregnancy 20+6 weeks or more, missed the best time for serological screening
Only maternal peripheral blood is needed, no risks for miscarriage
Comprehensive DNA testing, provide over 99% accuracy
Test can be performed at 12 weeks gestational age