The Rhesus NIPT

Anti-D prophylaxis is recommended in the 28th to 30th week of pregnancy for all RhD-negative women during pregnancy. However, Anti-D prophylaxis is not necessary if the fetus is RhD-negative as well.

The Rhesus NIPT enables the non-invasive determination of the fetal Rh factor. Non-invasive means that we only use the mother’s blood to determine the fetal Rh factor. Hence, there is absolutely no risk to the fetus, as the Rhesus NIPT only requires taking blood from the mother.

Similar to other non-invasive prenatal tests, we use the cell-free fetal DNA present in the mother’s blood. The fetal RHD gene is examined by means of PCR. Statistically, about 40% of the children of RhD-negative pregnant women are also RhD-negative, correspondingly a RhD-positive child can be expected in 60% of the tests.

With the Rhesus NIPT, unnecessary Rh prophylaxis can be avoided in every second to third pregnancy of RhD negative mothers.

The reliability of the Rhesus NIPT is very high. If it is performed after the 20th week of pregnancy (19+0), the sensitivity and specificity are:
Sensitivity: 99.93% 1
Specificity: 99.61% 2

The Rhesus NIPT can be performed earlier, namely from the 12th week of pregnancy (11+0) on. However, this leads to a slight decrease in accuracy: the sensitivity before 20th week of pregnancy is 99.91% 3.

You can decide whether you prefer Anti-D prophylaxis for all pregnancies of RhD-negative mothers. Or if you prefer to perform the Rhesus NIPT and limit Anti-D prophylaxis to a pregnancy with a RhD-positive fetus. Both options are identical with respect to the safety of your unborn child 4.

The performance of the Rhesus NIPT in rhesus-negative pregnant women is recommended in the current maternity guidelines.

Advantages:

With the fetal blood group determination of the Rhesus NIPT, the prenatal rhesus prophylaxis can be avoided in approx. 40% of pregnancies of RhD negative mothers. Without any risk to the unborn child.

  1. Legler TJ et al, Arch Gynecol Obstet 2021 Apr 9. doi: 10.1007/s00404-021- 06055-1
  2. Legler TJ et al, Arch Gynecol Obstet 2021 Apr 9. doi: 10.1007/s00404-021- 06055-1
  3. Legler TJ et al, Arch Gynecol Obstet 2021 Apr 9. doi: 10.1007/s00404-021- 06055-1
  4. Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen, www.iqwig.de/projekte/d16-01.html