Using A Blood Test To Determine Your Baby Gender. Why Not?

Are you pregnant or a future parent to be? A much-celebrated milestone in pregnancy is determining the gender of your little bundle of joy. Usually, this is done via ultrasound exam. However, does a method exist to determine gender earlier in pregnancy? How can it be done? How does it differ from traditional methods? In this article, I will cover traditional blood testing methods to find baby sex. Yes, it is possible to use a blood test to determine your baby gender.


Conventional methods require you to be in your fourth or fifth month of pregnancy before a blood test can be utilized to ascertain the baby's sex. However, it is possible to know your baby’s gender at the seven week mark, via blood testing. That concept may sound a bit confusing but fear not as I will break it all down, so you understand how it works.

What Do You Need to Know About Free Cell DNA Testing?

Recently, scientists have uncovered fetal genetic material is contained in the mother’s blood. This finding has opened up new ways and understandings in how to diagnose conditions without being invasive. A blood test can identify Down syndrome, a condition caused by a change in a fetus’s chromosomes that happens during pregnancy. Those born with Down syndrome have 47 chromosomes instead of the usual 46 chromosomes or can have changes in their chromosomes. The additional or unusual chromosomes can cause the body and brain to develop differently. As the condition is a life long one many parents like the ability to know and prepare should their child have Down syndrome.



The test can also identify other chromosome conditions starting at 10 weeks of pregnancy. Trophoblasts are specialized cells that develop into the placenta, The placenta delivers nutrients and oxygen to the developing baby and removes waste from the baby’s blood. Cell-free fetal DNA comes from trophoblasts. Scientists estimate that between 2-6% of the DNA in maternal blood comes from the fetus. It is this DNA that can be identified as early as seven weeks in pregnancy. As the pregnancy advances the amount of DNA increases.

The accuracy of the test is between 92 to 99% in determining conditions and the gender of the baby. The test can provide peace of mind to an expectant mother or parent as it offers a noninvasive method to determine these important traits. CVS and amniocentesis require the insertion of a needle into the uterus and carry a small degree of miscarriage. For many expectant parents having options regarding the baby is an important development.

How Does It Works

The tests basically determine the number of shards of fetal DNA in a sample of maternal blood work. The lab then analyzes the sample and number of shards. Having additional pieces of chromosome 21 suggests that the baby could have Down syndrome or trisomy 21.

The test detects the presence of Y chromosome in order to predict the baby’s gender.


Baby’s DNA in Mother’s Blood (via

​Gender Prediction Results

If the test detects Y chromosomes in the sample the baby is said to be male. If the test does not detect Y-chromosomes the gender is female and the level of fetal DNA is also low.

Free Cell DNA tests can be used to determine a number of things including paternity, typing Rh blood group, hemophilia, Duchenne’s muscular dystrophy, and congenital adrenal hyperplasia.


Free Cell DNA Compared with Conventional Procedures (resource

Below Are The Following That Free Cell DNA Can Detect

  • Paternity
  • Hemophilia
  • Rh Blood Group Typing
  • Duchenne's Muscular Dystrophy
  • Congenital Adrenal Hyperplasia

Free Cell DNA Testing Techniques

Step 1: cffDNA Purification

When blood is collected from the mother for testing it exists as whole blood. To properly test it, the blood must be separated into its components. The steps in this process are centrifugation, isolation, and purification. A centrifuge is a machine used often in labs. The machine spins a sample very rapidly, using the principal of sedimentation. The heavier portions of a blood sample would settle to the bottom and the less dense portions rise to the top. The centrifuged blood yields components that are more easily tested.



Formaldehyde is added to the mother’s blood sample. It will increase the amount of free fetal DNA in the blood sample. Formaldehyde works to hold the cells together during the testing phase. It also prevents the mother’s DNA from leeching into the sample. Without formaldehyde added to it a blood sample contains 0.40% free fetal DNA. By adding formaldehyde to a blood sample, free fetal DNA is increased to 20.2%.

Another method used to amplify the DNA has to do with the length of DNA fragments in the blood sample. This process is called size fractionation. A blood sample can be separated into its components based on their size. In regards to testing, in a blood specimen the method can separate strands of DNA based on the nucleotides, the building blocks of DNA. Almost 70% of total cffDNA can be obtained using size fractionation.

Step 2: Specification of Fetus DNA and Mutation Detection

Many expectant mothers and expectant couples undergo testing and genetic counseling during pregnancy. It allows them to understand many of the potential conditions their child could develop. For many it also allows them to use a blood test to find out gender.

  • Real-time Quantitative Polymerase Chain Reaction

Real-time quantitative polymerase chain reaction or qPCR is used in the lab to amplify the quantity of DNA. A fluorescent compound is added to the blood sample. In the PCR procedure, the sample is examined under a microscope to find any amplicons or bits of amplified DNA segments. If the sample shows a higher level of fluorescent activity that means that is an increase in the amplicons. The procedure can be used to look for a certain type of section of the DNA.

  • Nested PCR

Nested PCR is used to measure Y-chromosomes found in the blood sample. The test shows that 3 out of 25 women carrying female fetuses will have a certain Y chromosome sequence. The test is also about to test 53 out of 55 male fetuses. Overall this means the test has a sensitivity of 96% and a specificity of 88%.

  • Digital PCR

Nested PCR is used to measure Y-chromosomes found in the blood sample. The test shows that 3 out of 25 women carrying female fetuses will have a certain Y chromosome sequence. The test is also about to test 53 out of 55 male fetuses. Overall this means the test has a sensitivity of 96% and a specificity of 88%.

  • Shotgun Sequencing

This test is used to uncover trisomy, aneuploidy(abnormal number of chromosomes) and age of the fetus. This can be an important consideration for those who have had difficulty conceiving. The test comes with a 100% sensitivity and 97.9% specificity.

  • Mass Spectrometry

Once a sample has been run through PCR this procedure can locate the baby’s DNA. The PCR amplifies the DNA. The mass spectrometer changes molecules to ions that can them be further analyzed. They can be sorted and grouped by mass and magnetic charge. The test touts a 99.1% accuracy and a 98% sensitivity.

  • Mass Spectrometry

This test can detect cffDNA. In the lab, the plasma sample is treated with methylation enzymes. It can detect up to 88% of the mother’s material blood material.




These tests are specialized. Cell-free DNA offers a lot of information aside from gender identification of the fetus. It can be used during genetic counseling to identify fetuses with Down syndrome, chromosome abnormalities, and other conditions. These tests can quickly provide results. Further confirmation can be obtained via CVS or amniocentesis. Keep in mind test accuracy can decrease with slight obesity or pregnancy with multiple fetuses(twins, triplets, etc.).



I’m Elizabeth J. Johnson, a 30-year-old from sunny California. I have married to a wonderful man & have 2 little girls. They are the cutest lover, the sweetest hugger & the best inspiration.

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