Gender Reveal Testing Explained – Part 1

It may be that you, or someone you know, has received an inconclusive result and asked to provide another sample.

It is important to note that while this is disappointing, it does not in itself indicate a problem. There was simply not enough baby DNA detected in the sample to provide a reliable result on the day the blood was taken.

There are a number of reasons why this can occur:

1. Testing too early in pregnancy. This is the most common reason. If testing is carried out earlier than 6 weeks, there is not enough placental DNA in the bloodstream. Dating based on last menstrual period (LMP) can sometimes be inaccurate, as cycle length and ovulation timing vary between individuals. It is always advisable that a mother has an early scan to confirm the dates of the pregnancy before taking the test.
2. Low foetal fraction. The amount of placental DNA in the sample was too low for accurate analysis at the time of testing. Levels can vary throughout pregnancy.
3. Higher triglyceride (lipid) levels and a BMI over 30. Elevated levels of fat in the blood can occasionally interfere with DNA extraction and analysis. A high BMI can result in a higher volume of blood and therefore placental DNA is more diluted.
4. IVF pregnancies. Pregnancies conceived via IVF can sometimes have lower levels of placental DNA in the early stages, as the placenta develops slightly later.
5. Maternal age. In some cases, natural biological changes associated with maternal age can influence the amount or characteristics of circulating DNA.
6. Mosaicism. Rarely, natural variations in how genetic material is distributed between cells can make interpretation more complex.
7. Chromosomal variations. Uncommon chromosomal differences in either the mother or the pregnancy may affect the clarity of results.
8. Vanishing twin syndrome. This is when a pregnancy begins with two embryos, but one stops developing very early. The tissue is then naturally reabsorbed by the mother’s body, the placenta, or the surviving twin. This is not always visible on an early scan. When this has happened, DNA from the placenta of the non-viable twin may continue circulating at a very low level for some weeks after development stopped. See scan image below.
9. Pregnancy-related factors. In some cases, the pregnancy may not yet be developing in a way that produces sufficient detectable foetal DNA at the time of testing.

Vanishing Twin Syndrome on Scan