By Liz Wood, Health Testing Specialist at AlphaBiolabs
Last reviewed: 09/02/2026
In this article, we look at baby gender testing vs ultrasound scans for determining a baby’s sex.
At a glance
- The only reliable way to find out the sex of a baby before birth is with a DNA test, using a blood sample from the mother.
- Gender predictions made by ultrasound have an accuracy rate of around 90%.
- During an ultrasound scan, the baby’s position and the clarity of the pictures play a part in whether the ultrasound technician can accurately assess the sex of the baby on the day.
- An AlphaBiolabs Baby Gender Test is 99% accurate for determining a baby’s sex, from as soon as 6 weeks into pregnancy.
- This is made possible by cell-free fetal DNA (cffDNA), small fragments of an unborn baby’s DNA that pass through the placenta and circulate in the mother’s bloodstream during pregnancy.
- If a Y chromosome is present in the mother’s blood sample, this indicates that the baby is a boy. If no Y chromosome is present, this indicates that the baby is a girl.
Ultrasound more reliable after 18 weeks
The statement that gender predictions made by ultrasound have an accuracy rate of around 90% is backed up by Stephen Carr, Professor of Obstetrics & Gynaecology at the Warren Alpert Medical School of Brown University. Until the 14th week of pregnancy, baby boys and girls look exactly the same on ultrasound. Beyond this point, noticeable anatomical differences in the genitals can show up on the scan.
However, mistakes can be made when determining gender because it depends on the clarity of the images and the skills of the person interpreting them, he said.
According to Carr, it is preferable to wait until after 18 weeks of pregnancy to get a more reliable prediction of gender from an ultrasound scan. However, the baby will still need to be in a good position in the mother’s uterus (i.e. not in a breech or feet down position), and the legs will still need to be far enough apart to grant good visibility between them. So, wait until later and hope the baby is in a good position? It’s still not very reassuring, is it?
Baby gender testing from 6 weeks
Not only can a blood test be used to scientifically determine the gender of your baby, but it can also be performed at a much earlier stage of your pregnancy – from just 6 weeks.
The AlphaBiolabs baby gender test is a non-invasive DNA test, which means that there is no risk to the mother or the unborn child. No needles need to be inserted anywhere near the womb. A blood sample is all that is needed, which is usually taken from the mother’s arm. You will be responsible for arranging your own blood draw, and your test kit will contain full details on how to book a blood sample collection appointment through our recommended mobile phlebotomy service.
Our DNA scientists then analyze the expectant mother’s blood and look for any Y-chromosomal DNA. As the Y chromosome is male-specific, the detection of a Y chromosome is indicative of a male child. If no Y chromosome is detected, it is indicative of a female child. The mother needs to be at least 6 weeks pregnant to ensure that any Y chromosome present is at a detectable level.
The test can also be used in twin pregnancies, and will show whether at least one fetus is male, or that all fetuses are female.
Order an Early Baby Gender Test OnlineCan a blood test for gender be wrong?
Our prenatal gender testing is 99.9% accurate, making our results extremely reliable.
For the highest chance of a conclusive result, the mother must be at least 6 weeks’ pregnant to ensure that any Y chromosome present in the blood sample is at a detectable level for fetal sex determination.
Factors that can affect the results of the test include:
- The level of fetal DNA present in the blood sample at the time of testing. This is highly variable between individuals, and the test cannot determine the level of fetal DNA in the sample – only whether a Y chromosome is present.
- A vanishing twin may cause a false result.
Can an ultrasound be wrong about gender?
An ultrasound can be wrong about a baby’s sex.
Although ultrasounds are commonly used to determine the sex of a baby during pregnancy, especially around the 18–22-week mark, the results are not always accurate.
Factors such as the baby’s position, movement during the scan, or the clarity of the images can make it difficult for the technician to clearly identify the genital area, which may lead to an incorrect result!
In contrast, a prenatal gender test using a blood sample – like the one offered by AlphaBiolabs – looks for the presence of the male Y chromosome in the mother’s blood and can be performed much earlier in pregnancy (from 6 weeks).
With an accuracy of 99.9%, our Prenatal Gender Test offers a reliable alternative to traditional ultrasound scans for expectant parents who are eager to know the sex of their baby.
Order a Prenatal Gender Test nowCan you get conflicting gender results from a prenatal gender test vs an ultrasound?
It is possible to receive conflicting results from a prenatal gender test and an ultrasound, but this is usually due to differences in how the tests work and when they are performed.
A DNA-based test, like the AlphaBiolabs Prenatal Gender Test, analyzes fetal DNA found in the mother’s blood to determine the baby’s sex. This method is highly accurate (99.9%) and can be performed from 6 weeks into pregnancy.
An ultrasound relies on visual interpretation of the baby’s anatomy, usually performed around 18-22 weeks. Factors like the baby’s position, movement or clarity of the image can make it difficult for the sonographer to clearly see the genital area, increasing the possibility of human error.
Of the two tests, DNA testing offers a more scientifically accurate, reliable result.
Prenatal gender test vs ultrasound
| Feature | Prenatal Gender DNA Test | Ultrasound scan |
| How it works | Looks for the presence of a Y chromosome in the mother’s blood | Uses sound waves to create images of the baby |
| Earliest the test can be performed | From 6 weeks into pregnancy | Typically between 18-22 weeks into pregnancy |
| Accuracy | 99.9% accurate | Accuracy can vary (typically 80-95%) |
| Sample collection method | Blood sample collected by a phlebotomist | Conducted by a sonographer using ultrasound equipment |
| Risk of human error | Extremely low – testing performed at our ISO 17025 and BBB-accredited laboratory by expert geneticists | Higher risk – depends on technician and baby’s position on the day of the ultrasound |
| Convenience | Schedule a professional blood draw at your convenience | Requires an in-person appointment at a medical facility |
| Suitable for early planning | Yes – ideal for gender reveal planning | No – requires waiting until later in pregnancy |
How can I get a baby gender test?
Taking our Prenatal Gender Test couldn’t be easier!
Simply order your test online for just $99, and we’ll mail your test kit to you immediately. The cost of your test includes your test kit, mailing of the test kit, all lab fees, and a password-protected digital copy of your test results.
The test requires a blood sample from the mother, which must be collected by a medical professional (phlebotomist). Your test kit will contain full details on how to book your blood draw through our recommended mobile phlebotomy service.
You’ll receive your test results in 3-4 business days after we have received your sample.
