Baby gender testing – what you need to know

Pregnancy is an exciting time for expectant parents as they wait for the arrival of their new bundle of joy.

But one of the most significant milestones is when they finally have an answer to that all important question – boy or girl?

If you are expecting a baby, or know someone who is, you may be wondering how baby gender is determined. And whether it is possible to say with 100% certainty before the birth whether the baby will be a boy or a girl.

In this blog, we share 10 facts about baby gender that you may not know, including how and when a baby’s sex is determined, and how blood testing remains the most effective way to determine prenatal gender…

10 facts about baby gender

1. Biological sex is determined at the time of conception…

From the moment of fertilisation, one chromosome from the egg and one chromosome from the sperm determine the sex of the baby.

The Y chromosome is present in males, who have one X and one Y chromosome, while females have two X chromosomes. These chromosomes are known as the sex chromosomes.

2. …but foetal genitalia won’t be visible until much later in pregnancy.

Baby boys and baby girls look exactly the same on an ultrasound scan up until around 14 weeks of pregnancy.

For this reason, parents must usually wait until the 20-week ultrasound scan to get an idea of whether they are having a boy or a girl.

3. A baby’s sex depends on which sperm wins the race…

Every egg has two X chromosomes, while sperm have either an X or Y chromosome.

If a sperm carrying an X chromosome fertilises the egg, the baby will be a girl. 

If a sperm carrying a Y chromosome fertilises the egg, the baby will be a boy.

4. Ultrasound scans cannot guarantee the sex of your baby.

While a qualified sonographer may be able to provide an answer on gender during an ultrasound appointment – usually from around 20 weeks into pregnancy – this is not always accurate.

This is because it is not always possible to see the baby’s genitals clearly in the womb, depending on how the baby is lying on the day of the ultrasound.

Ultimately, the accuracy of the ultrasound depends on a variety of factors including the clarity of the images, and the skills of the person interpreting them.

5. Old wives’ tales can’t be used to predict a baby’s gender.

Advances in medical science, from ultrasound scans to DNA testing, mean that parents no longer have to wait until a baby is born to find out whether they are having a boy or a girl.

However, myths persist regarding how to predict a baby’s gender before they are born.

From pregnancy cravings to the shape of the bump, these old wives’ tales cannot be relied upon to determine a baby’s sex.

So, if you’ve been craving sugary treats, don’t go painting the nursery pink just yet!  

6. There’s no proof that family history plays a role in foetal sex determination.

While it is possible that family history plays a part in a baby’s sex, there is no scientific evidence to suggest that it does.

As far as we know, baby gender is still all down to chance.

7. Baby gender cannot change during pregnancy.

As mentioned, a baby’s sex is determined from the moment of conception.

This does not change at any point during pregnancy.

8. There’s no way of guaranteeing a boy or a girl.

Rumours persist regarding whether you can have any influence over the sex of your baby.

From having sex a few days prior to ovulation, to making changes to your diet, there are lots of ‘tips’ that have been shared online depending on whether you would prefer to conceive a boy or a girl. 

However, there is no scientific proof that any of these will make a difference to the gender of your baby.

9. It’s not quite 50/50…

While it is generally understood that the odds of having a boy or a girl are around 50/50, this is not strictly true.

In fact, the World Health Organisation (WHO) has previously stated that a ‘biologically normal’ sex ratio at birth ranges from 102 to 106 male births, per 100 female births. 

This means that there is a very slight bias towards male births. Although this can vary by population and has also been known to vary at different points throughout history.

10. Blood testing is the only foolproof way to find out the sex before a baby is born.

A blood test is the only 100% accurate way of determining the sex of a baby while they are still in the womb.  

As mentioned above, ultrasound scans are not always accurate, because the technician needs to be able to get a clear view of the baby’s genitalia to make a determination on gender.

For a blood test for gender – also known as a baby gender test or prenatal gender test – the mother’s blood sample is analysed by expert geneticists who look for the presence or absence of a Y chromosome within the mother’s blood.

Every human being has a pair of sex chromosomes in each cell. The Y chromosome is present in males, who have one X and one Y chromosome, while females have two X chromosomes.

If a Y chromosome is detected in the mother’s blood sample, this indicates that the baby is a boy. If no Y chromosome is detected, this indicates that the baby is a girl.

For the highest chance of a conclusive result, the mother must be at least 8 weeks pregnant when providing a blood sample for testing. This is to ensure that any Y chromosome present is at a detectable level.

Where can I buy a Baby Gender Test?

Boy or girl? Find out for sure with the AlphaBiolabs Baby Gender Test. 

Our test can be performed from as early as 8 weeks into pregnancy, with only the mother’s blood sample required, and is 100% safe for mother and baby.

The blood sample can be collected at a time and location of your choice. You can either:

• schedule a FREE sample collection at one of our walk-in centres or
• have an AlphaBiolabs sample collector visit you at a convenient time or location*

The cost of the test includes your test kit and all lab fees, with results available in just 3-4 days.**

It’s easy to order online now.

Got questions about the test? Call our Customer Services team on 01 402 9466, email info@alphabiolabs.ie or visit our Learning Centre for more information.

*Additional charges apply

**From receipt of your samples at the laboratory