By Beata Anderson

Some people love the suspense of not knowing the sex of their baby until the delivery. But some of us can’t wait to find out much sooner.

Only a medical professional with relevant training can reliably determine the sex of a baby. Yet, this doesn’t stop many from predicting the sex of their baby based on old wives tales. When it comes to finding out the sex of your baby, there isn’t one single test that is used for everyone. So, if you want to know the sex ahead of time, there are different tests at different stages of your pregnancy. But while many of these tests are reliable, they’re not all suitable for everyone. Some carry significant risks (like CVS or Amniocentesis). The ultrasound scan offered by the NHS between 18-22 weeks of gestation, but by following the Fetal Anomaly Screening Programme guidelines, finding out the fetal sex is not mandatory – the scan checks fetal anatomy to exclude certain anomalies and to check your baby’s growth.

Non-invasive prenatal test

A non-invasive prenatal test (NIPT) checks for chromosomal conditions like Downs syndrome. You can have this test starting at 10 weeks of pregnancy. It is not a diagnostic test. It only screens for the possibility of your baby having certain chromosomal conditions. If your baby has abnormal results, we would refer you to your local Fetal Medicine Unit where the specialist consultants will take over your care, and discuss further plans with you and your partner.

For the NIPT test, you would provide a blood sample, which is then sent to a lab and checked for the presence of fetal DNA linked to chromosome disorders. This test can also accurately determine the sex of your baby. Because this is a non-invasive test, giving a blood sample doesn’t pose any risk to you or your baby. Although an NIPT is not designed to purely find out fetal sex and we would advise against you having one for the sole reason to find out fetal gender.

At-home testing kits

Along with traditional methods, some people have a positive experience using at-home kits marketed as “early baby gender blood tests”. Some of these tests (according to claims) can determine the sex as early as 8 weeks, with about 99 percent accuracy. However, these are claims made by the companies and there isn’t research to back up these statistics.

This is how it works:

You take a sample of your blood, and then send this sample to a lab. The lab checks your blood sample for fetal DNA, looking specifically for the male chromosome. If you have this chromosome, you’re supposedly having a boy. And if you don’t, you’re having a girl. Keep in mind that when sending samples through the mail to an unknown lab there are many factors that may reduce the reliability of the results. These tests tend to be expensive so you may want to consider whether they are worth the cost for you.

Old wives’ tales

Some people even use old wives’ tales to predict their baby’s sex. According to folklore, if you’re extra hungry during pregnancy, you’re probably pregnant with a boy.  It’s believed that extra testosterone secreted by a baby boy increases appetite. There’s even the belief that a higher fetal heartbeat (over 140bpm) means you’re having a girl. And that you’re carrying a girl if you’re forgetful during pregnancy. Some even believe that you’re having a boy if your bellow is low and a girl if your belly is high. But while old wives’ tales are a fun way to predict the sex of a baby, there isn’t any science or research to back up these beliefs or claims. The only way to know what you’re having is to wait for your routine 20 weeks anomaly scan or to book a private gender scan after 16 weeks in the pregnancy.

Why do you wait till 16 weeks of gestation?

There has been many studies and research into determining fetal sex in the first trimester. Most of these studies concluded the accuracy in determining gender increased with growing fetal size. One of these studies conducted by Kearin et al (2014) found that ultrasound gender predictions by sonographers are 100% sensitive for accurately predicting the gender in the second and third trimesters. The overall success rate of correctly identifying fetal gender in the first trimester was much lower  at 75%.

At Somerset Early Scans we offer gender scans from 16 weeks of gestation as it is the time where we we can safely and more accurately find out fetal sex. Fetal gender is 97% accurate at 18 weeks and a little less below that gestation. If you attend below 16 weeks of gestation your chances to find the desired information becomes less accurate and sometimes we will not be able to determine the gender at all at that stage. Please note in our clinics we do not offer a photo of your baby’s genitalia but we will write it on your scan report with your consent.

Accuracy of sonographic fetal gender determination: predictions made by sonographers during routine obstetric ultrasound scans – Kearin – 2014 – Australasian Journal of Ultrasound in Medicine – Wiley Online Library


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