Baby gender test vs. Ultrasound

Liz Wood AlphaBiolabs

By Liz Wood, Health Testing Specialist at at AlphaBiolabs
Last reviewed: 26/05/2023

Whether your baby will be a boy or a girl is determined at the time of conception, long before most women even know they are pregnant.

The egg from the mother and the sperm from the father both carry sex chromosomes. The egg always contributes an X chromosome, and the sperm can contribute either an X or a Y chromosome. The sex of the baby is thus determined by the sperm cell that fertilises the egg first. If the sperm is carrying an X chromosome, the baby will be a girl. If the sperm is carrying a Y chromosome, the baby will be a boy.

Despite a baby’s gender being determined when the egg is first fertilised, pregnant women have to wait until their mid-pregnancy scan at around 16 weeks to determine the sex of their baby. However, ultrasound shouldn’t be relied upon. Statistics show that ultrasounds can be wrong up to 10% of the time. That means up to 10 women out of 100 will be told that they’re having a boy or a girl, only to have quite a surprise at the birth!

A quick trawl on the internet shows hundreds of messages from frustrated mothers, complaining about being given the wrong gender prediction at their ultrasound scan.The fact is that if the technician can’t get a clear view of the baby’s genitals, it may not be possible to tell for sure. The baby may be in a tricky position, the technician may not have sufficient expertise, the scan may have been performed too early, or the image may not be adequately clear. What we need to remember is that ultrasounds are an essential tool for monitoring the healthy progress of a pregnancy, but were not designed for gender prediction.

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. 

Our DNA scientists then analyse 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 foetus is male, or that all foetuses are female.

How can I get a baby gender test?

Taking one of our baby gender tests could not be easier.

You can order your baby gender test here or call our friendly team on 0140 29466.

You can choose from the following sample collection options:

  • Have your blood sample taken at our Walk-in Centre
  • Have one of our sample collectors visit your home or another place that is convenient to you

You will receive your confidential results within 3-4 working days after your samples have been received by our laboratory.

Order a baby gender test today

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Liz Wood AlphaBiolabs

Liz Wood

Health Testing Specialist at at AlphaBiolabs

Liz joined AlphaBiolabs in 2021, where she holds the role of Health Testing Specialist.

As well as overseeing a range of health tests, she is also the lead on several validation projects for the company’s latest health test offerings.

During her time at AlphaBiolabs, Liz has played an active role in the validation of the company’s Genetic Lactose Intolerance Test and Genetic Coeliac Disease Test.

An advocate for preventative healthcare, Liz’s main scientific interests centre around human disease and reproductive health. Her qualifications include a BSc in Biology and an MSc in Biology of Health and Disease.

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