Glengarry Private Hospital
Part of Ramsay Health Care

When can I find out my baby's sex?

Finding out your baby’s sex is one of the most exciting steps in your pregnancy journey. And newer technologies mean you can find out as early as 11 weeks.

Back in our grandparents’ days, the sex of every baby was a surprise. But with the increasing use of ultrasounds in the 1980s, expectant mums and dads had the opportunity to see their babies on a scan (admittedly a far grainier image than we’re used to nowadays).

Ultrasound is still incredibly common – and used for a multitude of reasons other than finding out the sex – but there is also a newer, very accurate and safe method on the market known as the Non-Invasive Prenatal Test (NIPT). And it allows for the big gender reveal much sooner.

When can I find out the sex with ultrasound?

An ultrasound is an image created by high frequency sound waves to see your baby in the womb. It’s safe, non-invasive and painless. Find out more.

You can usually find out the sex as early as 16 weeks. You may not have a scan at this point so many parents find out at the routine 18- to 20-week anatomy scan; however, whether or not it is a successful task depends on a few factors. Firstly, when the baby’s genitals are visible to the sonographer and secondly, if they are in a favourable position. Sometimes the baby might be crossing their legs, they’re in a particular position and unwilling to move, or they could even be asleep. It may also depend on factors to do with the mother, including excess weight and the amount of amniotic fluid.

Newer methods: Non-Invasive Prenatal Test (NIPT)

This simple blood test can be conducted from 10 weeks’ gestation, although the ideal time is between 11 and 13 weeks. There are several companies that analyse the results, so you may be more familiar with their brand names, Generation or Harmony. The NIPT accesses the baby’s genetic material that is circulating naturally in the mother’s blood and looks for chromosomal abnormalities. Specifically:

  • Trisomy 21 (Down syndrome)
  • Trisomy 18 (Edwards syndrome)
  • Trisomy 13 (Patau syndrome).

A bonus of the NIPT is that it can also look for the XY (male) or XX (female) chromosomes, if you opt in for this. The result is 99 per cent accurate; however, sometimes the test fails because there may not be enough concentration of the baby’s DNA yet and sometimes there are maternal factors such as obesity, infection or inflammation. The NIPT can’t be used for twin pregnancies. Find out more.

Old wives' tales about sex

You cannot tell the sex from:

These may be fun ways to guess the sex, but the most accurate way to find out is with an ultrasound or the NIPT. It will be worth the wait.

Dr Stas Vashevnik is a private obstetrician and gynaecologist at Glengarry Private Hospital in Perth’s northern suburbs. He has a keen interest in complex deliveries and helping women with recurrent miscarriage. Contact his rooms on (08) 9246 1166 or