Out of all the questions asked of mums-to-be, "Do you know what you're having?" would be right up there in popularity.
While some wait until the big day for the big reveal, many couples can answer that question with confidence after their second scan. Finding out which sex the baby is can help with early decision making in regards to the baby's name, help the parents-to-be chooose to decorate the nursery in a gender-specific way, and give hints of what colour onesies to buy.
Once upon a time, couples would use old wives' tales to give a hint as to what they were expecting. If it's a boy you'll be carrying low, they said; if it's high, it is a girl. Cravings for sweetness mean you're having a girl, versus savoury for boys, other said. The baby's heart rate is also an old favourite for predictors.
Now, of course, we've moved on to the use of scientific methods that have a higher success rate. The 18 to 20-week ultrasound has become more known for gender prediction than the initial intention to identify medical conditions.
However, it is well known that ultrasound is not 100 per cent accurate: one study reported that 3.3 per cent of foetal genders were incorrectly assigned at the 20-week scan.
The newest technology is non-invasive prenatal testing (NIPT). This blood test is known to have an excellent accuracy rate of gender identification (in addition to checking for Down syndrome and other chromosomal abnormalities, including Trisomy 13 and Trisomy 18), and can be undertaken as early as nine weeks gestation.
While there is a high accuracy rate, it is not guaranteed, and the small inaccuracy in various methods has resulted in women receiving a surprise in the delivery suite.
Belinda* is one of those women.
Belinda and her husband Tom* already had a son when their second baby was identified a girl by ultrasound. They were thrilled, and with no indication of the reliability of the scan, a name was chosen and the nursery decorated for their expected daughter.
As they prepared to meet their baby girl in the delivery suite, Belinda and Tom received a huge surprise. "I remember my obstetrician proudly saying 'It's a boy!'" Blienda remembers. "I thought, 'he said boy but he must mean girl'."
But no, the doctor was correct: they had another son.
While Belinda was initially shocked, she says that when the staff placed Cooper in her arms for the first time, there was never any doubt of her love for him.
She did, however, feel an overwhelming sense of loss for the baby girl she thought she had been bonding with over the past nine months.
"I had this weird feeling, like a piece of me had gone missing ... In a matter of seconds, she had simply ceased to exist. Instead in her place I held a beautiful baby boy, with piercing blue eyes. It was a strange and bittersweet experience," Belinda says.
Boys' names had not even been considered, so their new son was nameless for the first three days. In addition, Belinda had no baby clothes for him to wear that weren't pink or purple. "To make matters worse, I couldn't return any of the little girl clothing I'd purchased as I had already cut the tags off everything and washed it all. I remember saying to my mum, 'I don't care what you do with it, but please make it all go away'."
If Belinda and Tom had another child, would they find out the sex? "Definitely not. I would love that baby regardless of their sex but I think it is the build-up, the expectation of one thing but getting something entirely different, that was the hardest thing to take," Belinda says.
That same feeling of expectation was felt by Tanya* and Anthony* before the arrival of their first child. With no confirmation of their baby's gender at the 18 to 20-week scan due to positioning, a 4D scan was arranged. So at 30 weeks pregnant, Tanya found out she was having a boy. They were informed the baby's sex was determined as 99 per cent accurate from the view of the baby's scrotum.
The couple happily awaited the birth of their son with a themed nursery and a wardrobe full of boy clothes. A baby shower was held with their baby boy's name sprawled across a large banner.
On the big day, an emergency caesarean section was necessary. The doctor enquired if Tanya knew the sex of their baby, to which she confidentally told him that she was having a boy. The doctor answered, "Well if it's not we'll send it back then."
Upon delivery, she was astounded to hear the doctor say, "Well, it looks like it's going back then." Her husband, as shocked as she was, repeated "no, we're having a boy" as the staff confirmed the birth of their baby girl.
While a surprise at first, once Tanya held her daughter, the feelings and emotions took over, and it really didn't matter what sex she was.
And the experience didn't stop Tanya and Anthony asking the gender of their child when they fell pregnant again. "We found out at the earlier scan at 18-20 weeks that we were having another girl - and this time they got it right," Tanya says.
*Surnames withheld