What is the best way to find out the gender of your baby?

Claire Thomas, Alphabiolabs

By Claire Thomas, DNA Technical Manager at AlphaBiolabs
Last reviewed: 19/06/2024

While some people choose to wait until the birth to find out the sex of their baby, many people want to find out earlier, so that they can prepare for their new arrival.

There are several ways you can find out the sex of your baby. However, there are many important factors to consider before choosing a test that’s right for you – including how soon testing can be done, and whether there are any risks involved.

In this article, we look at the different testing methods available for finding out the sex of your baby before birth, and how to decide which test is best for you.

Blood testing

How does blood testing work for baby gender?

Traditionally, women could find out the sex of their baby from ultrasound scans performed around 16 weeks into pregnancy, or after having amniocentesis or chorionic villus sampling (CVS) procedures carried out as part of their antenatal health care.

However, scientific advancements have made it possible to accurately determine a baby’s gender from as early as six weeks into pregnancy, with only a blood sample from mum required.

Blood testing for baby gender is 100% risk-free for mum and baby and works by detecting small amounts of foetal DNA in the mother’s bloodstream, which begins to circulate from around 6 weeks into pregnancy.

Highly sensitive testing methods are then used to detect Y-chromosome DNA in the mother’s blood sample.

Because the Y chromosome is only found in males, the presence of a Y chromosome indicates that there is a 99% chance that the baby is a boy. If no Y chromosome is detected, then there is a 99% chance that the baby is a girl.

Which blood testing methods can be used to find out a baby’s gender?

AlphaBiolabs provides two options for blood testing for baby gender:

  • At-home Baby Gender Test

    This test allows you to collect your own blood sample in the comfort of your own home, with our easy-to-use, TinyTAP collection device. The TinyTAP device enables you to painlessly collect a very small amount of blood from your upper arm, with no clinical appointments required.

    Simply follow the instructions included with your test kit to collect your own sample and return it to our laboratory for testing. Your secure results will be emailed to you within 3 working days*, or the next day if you choose to upgrade to our Express Service (additional fees apply).

    This method is also ideal for people who are needle-phobic, as no venous blood draw is needed.

    We are the only UK laboratory to offer this highly convenient, fuss-free method of blood sample collection for baby gender testing!

    *From receipt of samples at our laboratory, before 10am

  • Clinical Baby Gender Test

    This test is ideally suited for people who would still like to benefit from having their blood sample collected using our pain-free TinyTAP device, but would prefer the collection to be performed by one of our professional sample collectors.

    Laboratory analysis is performed in exactly the same way as with our At-home Baby Gender Test, so you will still receive accurate, reliable results. The only difference is that you can choose to have your blood sample collected:

    • At one of our nationwide walk-in centres* OR
    • At a convenient time or location of your choosing*

    *Additional charges apply

    Simply place your order online, and our Customer Services team will contact you to arrange your sample collection appointment.

    If required, it is also possible for our sample collectors to perform a standard venous blood draw (where the sample is taken from a vein in your arm), instead of using our TinyTAP device. If you would prefer a venous blood collection, please speak to our Customer Services team who will be able to arrange the appointment and collection method that is best for you.

Although some companies offer baby gender testing using finger prick blood samples, this is not a collection method we offer for baby gender testing at AlphaBiolabs, for several reasons:

  • For a finger prick blood collection, a small finger prick lancet device is used to prick the tip of the finger. Blood must then be squeezed into a collection tube. In many cases, the process needs to be repeated on multiple fingers, which can be difficult and messy.
  • Collecting blood from the fingertips can be painful and time-consuming.
  • It is difficult to adequately clean the fingertips to ensure that there is no male DNA present. This means that the likelihood of male DNA contamination is higher with finger prick baby gender tests, increasing the possibility of a false result (where a Y chromosome is detected, leading to baby girls being incorrectly identified as baby boys).

How does an ultrasound scan work for baby gender?

An ultrasound scan is performed by a qualified sonographer, and uses a process called sonography to visualise the inside of the body.

The scan is performed using a probe which produces soundwaves. These soundwaves bounce back from the body, creating internal images that can be examined by the sonographer.

Ultrasound scans are non-invasive and are typically carried out by healthcare providers as part of the mother’s antenatal care. They can be used to determine a baby’s sex from around 16 weeks into pregnancy.

However, ultrasound scans are not always accurate. This is because the sonographer must be able to get a clear view of the baby’s genitals in utero, which is not always possible depending on the way the baby is positioned at the time of the scan.

How does Chorionic Villus Sampling work for baby gender?

Chorionic Villus Sampling (CVS) is an invasive procedure that is typically only offered to pregnant women who are at high risk of having a baby with a genetic or chromosomal abnormality (e.g. Down’s Syndrome). It can also be used to determine the gender of the baby.

During a CVS test, which is performed from 11-14 weeks into pregnancy, cells are obtained from the placenta by guiding a thin tube through the cervix, or by inserting a needle into the uterus to remove a sample of chorionic villus cells.

Unlike non-invasive testing methods (such as blood testing for baby gender), CVS testing carries a small risk of miscarriage.

How does amniocentesis work for baby gender?

For amniocentesis, a small sample of amniotic fluid (the fluid surrounding the baby) is extracted from the uterus using a long, thin needle which is inserted into the abdomen.

As with CVS testing, amniocentesis is usually performed for high-risk pregnancies, where there is a chance that the baby may have a genetic or chromosomal abnormality.

The test is performed from 15-18 weeks into pregnancy and carries a small risk of miscarriage.

Is it possible to predict baby gender without a DNA test?

There are still many myths surrounding how to find out a baby’s biological sex – many of them old wives’ tales with no basis in scientific fact.

Not only are these myths misleading, but they can also cause disappointment for expectant parents.

Chinese gender prediction chart

The Chinese gender predictor chart is said to have been found over 700 years ago, in a royal tomb near Beijing.

It is thought that the chart can be used to predict a baby’s gender using the age of the mother at the time of conception (when she first became pregnant), and the approximate date when conception took place.

These dates are then converted into dates on the Chinese lunar calendar to predict whether the baby is a boy or a girl, based on the mother’s lunar age, and the lunar date of conception.

Mayan calendar gender predictor

The Mayan calendar theory is very similar to the Chinese gender predictor chart, in that it uses the mother’s age and the month of conception to determine baby gender. However, the calculation is much simpler.

If both numbers (mother’s age and month of conception) are odd, or both numbers are even, it is thought that the baby will be a girl.

If one number is even and the other is odd, it is thought that the baby will be a boy.

Other common gender prediction myths include…

  • The ring test – to perform the ring test, the mother lies on her back and another person dangles her wedding ring over the baby bump on a piece of thread. If the ring moves back and forth over the bump, it’s said that the baby is a boy. If it moves in a circle over the bump, it’s a girl.
  • Baby bump shape – a common myth persists that you can tell the sex of the baby from the shape of the mother’s bump. ‘Carrying low’ is a term that’s often used to describe the baby bump sitting closer to the hips. Historically, this was thought to indicate that the baby was a girl. ‘Carrying high’ or having a protruding bump was thought to indicate a boy.

Of course, while it can be fun to guess the sex of a baby before it’s born, it’s worth noting that the only 100% accurate and reliable way of finding out the sex of a baby before birth is with a DNA test.

So, we’d recommend taking the results of these gender prediction methods with a very big pinch of salt!

How do different baby gender tests compare?

The table below shows how different baby gender testing methods compare, including how soon each test can be performed, potential risk to mum and baby, test accuracy, and whether the test allows you to collect your own sample.


Performed at

Risk to mum and baby


Collect your own sample

Pain level

Risk of male DNA contamination

Rapid results

No appointment needed

TinyTAP home blood collection device

Clinic blood draw

Finger prick (lancet) blood collection

Ultrasound scan


Chorionic Villus Sampling (CVS)

6 weeks

6 weeks

8 weeks

16+ weeks

15-20 weeks

10-13 weeks

100% risk-free

100% risk-free

100% risk-free

100% risk-free

Small risk of miscarriage

Small risk of miscarriage



< 70%





Low to moderate pain

Low to moderate pain


Moderate discomfort

Moderate discomfort

Virtually no risk

Virtually no risk

Potential risk

No risk

No risk

No risk

What’s the best way to find out the sex of your baby before birth?

The best way to accurately determine the sex of your baby before birth is to take a DNA test.

If you want to find out the sex of your baby as soon as possible, without having to make a clinical appointment, our At-home Baby Gender Test is the test for you.

Collect your own blood sample in the comfort of your own home using our innovative, pain-free TinyTAP device, and return your sample to our laboratory. Your secure results will be emailed to you in just 3 working days, or the next day if you upgrade to our Express Service.

We are the only UK laboratory to offer the easy-to-use, fuss-free TinyTAP device for baby gender testing!

Alternatively, you can choose to have your blood sample collected by one of our professional sample collectors* at one of our nationwide walk-in centres or at a time and location convenient to you (via TinyTAP or venous blood draw).

Order your Baby Gender Test online now, call 0333 600 1300 or email info@alphabiolabs.com.

*Additional fees apply

Baby Gender Testing

Boy or Girl? Find out for just £89 with results in 3 days

Claire Thomas, AlphaBiolabs

Claire Thomas

DNA Technical Manager at AlphaBiolabs

Claire joined AlphaBiolabs in 2018 and holds the role of DNA Technical Manager, working within the genetics team.

A highly-skilled geneticist, Claire is a member of the International Society for Forensic Genetics (ISFG), and holds a BSc in Biochemistry.

Claire’s main responsibilities include ensuring all members of the DNA team adhere to ISO 17025 accreditation standards, and that they are comprehensively trained in the latest techniques for DNA analysis.

She also oversees the quality and integrity of AlphaBiolabs’ DNA test reports, ensuring the very highest standards are maintained.

Prior to joining AlphaBiolabs, Claire completed an internship in Molecular Genetics with the NHS, providing services for the diagnosis of inherited disorders.

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