1. Baby’s heart rate is slower than 140 beats per minute
This test of a baby’s sex suggests that if the heart is pumping faster than 140 beats per minute, you will be having a girl. Although it sounds like a medical diagnosis, a study that was carried out from 1997 to 2003 on 477 bubs tested in the first 12 weeks, showed that boys’ hearts clocked in a little bit faster at 154.9 beats per minute while girls strolled in at a leisurely 151.7.
Meaning overall, the study just showed that all babies tend to have a heart rate over 140 beats per minute in the first trimester, regardless of their sex.
Interestingly though, during labour, female babies do have faster heart rates than boys.
2. Morning sickness that’s not too bad
It has been suggested that pregnant with boy symptoms include less vomiting because higher hormone levels in girl babies cause worse morning sickness. British medical journal The Lancet did publish one study to show that mothers with hyperemesis gravidarum (extreme morning sickness suffered by the likes of Princess Kate and Amy Schumer) are more likely to have girls.
But, as you may recall, poor old Kate was affected by this condition for each of her three pregnancies, and in the end the odds went the way of the boys, with two sons to one daughter. So it's clearly not a sure-fire predictor of the baby’s sex. Also, if it's your first child, how would you know if the morning sickness is worse or not?
3. Lustrous hair and skin
When up the duff with a boy, the old wives tales say your skin is more likely to be pimple free (again, due to not having those pesky girl hormones alleged to cause breakouts) and your hair thick and shiny (because of the benefits of male testosterone).
In reality, pregnancy plays whack with all your hormones and the difference between boy baby and girl baby hormones is not significant. It could go either way, or both – good and bad skin, full and limp hair - over the course of the nine months.
The Sun does report a French study that says "mums who suffer from acne while pregnant are 90 per cent more likely to give birth to a girl."
In an article on Carolina Parent, Dr Kelly Leggett weighs in on the hair myth: "Your age will affect your hair texture more than your pregnancy."
"Normally, a woman loses about 100 hairs a day as part of hair growth's natural cycle," ob-gyn Dr Aviva Stein says in the same article. "During pregnancy, regardless of baby gender, the hormone estrogen prolongs the pregnant woman's hair-growth phase, resulting in less shedding of hair."
4. If it’s all out front
Another long-believed story is that if the pregnancy weight gain is heavy on the hips and bum, it’s a girl (due to that pesky estrogen again) but if the baby seems to only be a bump out front, then it is more likely to be a boy.
According to the BBC, this theory doesn't hold water, as the shape of the bump depends on the foetus's position: "If it has its back alongside the mother’s front this makes her belly stick right out. If the baby’s back is parallel with the mother’s back the result is that the abdomen looks flatter. And as the position the developing baby adopts is not dependent on its sex, it is a myth that the shape indicates whether it is a boy or a girl."
Also, putting on weight in the hips and bum is the natural storage for the extra nutrition a baby of either sex needs. "The rear end is exactly where we want a woman to put on weight," says Professor Kathleen M. Rasmussen. "Fat stored there is not visceral, it doesn't end up in hard-to-break-down adipose tissue the way it would in her abdomen, making it much easier to lose after pregnancy."
5. A hankering for chips, not ice cream
There is a theory going around that if you crave salty, savoury foods, you are having a boy, and that if the desperate desire is for sweet stuff, it's more likely to be a girl. Kinda like that whole That’s What Little Girls Are Made Of Rhyme, suggesting “sugar and spice and all things nice” means a daughter.
So what happens if you crave the old pregnancy favourite of pickles and ice-cream combo? Savoury and sweet?
"There's no scientific evidence to back up any of these beliefs," Livestrong.com reports of the suggestion in an article all about cravings.
In fact, that little critter inside you is just sucking up all your nutrients as it grows, so what you crave is most likely what your body is running out of, regardless of if it’s a boy or a girl.
6. Big appetite
The old story that mums eat more when carrying boys seems to be fact, with a US study reporting that of 244 women tested, on average those with boys on board ate 10% more than those with girls.
In the British Medical Journal, Prof Dimitrios Trichopoulos writes: "Our findings support the hypothesis that women carrying male rather than female embryos may have higher energy requirements."
7. Keeping it on the down-low
The most popular belief about how you can tell what sex the baby will be is by looking at how you are carrying, with the theory that girls sit higher, and boys hang down the bottom.
Similar to the "where you gain weight" theory, there doesn’t seem to be any good reason – or basis – for this old wives tale.
Professor Steve Robson, the Vice President of the Royal Australian and New Zealand College of Obstetricians and Gynaecologists, told The Huffington Post Australia, “It’s clear to say that a child’s genitals has nothing to do with how the woman’s body looks when she is pregnant. The way a woman carries a baby has more to do with the size of the baby - then the belly tends to pivot forward."
8. The wedding ring spin
Tie your ring to a piece of string and hold it in front of your belly. If it swings backwards and forwards, it’s a boy, but if it goes around in circles, it’s a girl. (Though some sites say it’s the other way around! So that just goes to show you how reliable this myth is...)
WATCH: Fiona Falkiner is having a baby boy!
9. A wee trick
Like the pH of your pool, you can test your pee. Adding Draino (drain cleaner) to your urine supposedly turns it green for a girl and blue for a boy. What if it’s aqua? In fact, the many sites suggesting this method can not agree what colour indicates what result.
Also, VeryWellFamily reports that it is extremely dangerous to mix these two substances as it can cause fumes that are not at all healthy.
A safer way suggested by Healthy Mummy is to add bicarb to your pee. If it fizzes, it's a boy.
Medical News Today says this whole theory is untrue though. "There is no proof that the sex of an unborn baby has any effect on the pH of a woman's urine. Also, many other known factors can make a woman's urine more or less acidic."
10. Chinese birth chart
Hmmm. Apparently an ancient Chinese document just requires the Chinese age of the mother and the Chinese month of conception to work out the sex of your child. You can try it here.
But as the mother of twins, one a boy and one a girl, who I guess were conceived in the same month and while I was the same age, this method would have a definite 50% failure rate for me.
WATCH: Sam Frost reveals the gender of her and Jordie Hansen's baby
11. The key to it all
A bit of a flaw with this method: you can’t do this one if you’ve read this. A key is placed in front of a pregnant woman. If she picks it by the top, fatter bit, instead of by the long narrow bit, it’s a boy. This one definitely veers towards the story-of-an-elderly-married-woman variety.
12. Skinny dads
There seems to be some merit to this one; a Danish study showed that fathers who put on more weight during their partners pregnancy were more likely to have girls.
13. Best foot forward
The 15th century Distaff Gospels advised that those who walk with their right foot first are expecting a boy. Unsurprisingly, we can't find any research on this theory.
14. Mother’s Intuition
Guessing the sex of your child, you would expect to get it right 50% of the time. But a New Scientist study has proved that maternal instinct - where the mum-to-be just has a gut feeling – is proved right more often than not, with correct guesses around 70% of the time.
15. Over the counter gender tests
Available from the likes of Chemist Warehouse, these products are supposed to be able to tell you the sex of your baby from 10 weeks.
The reviews are mixed. There does not seem to be any formal studies proving their accuracy and and the Intelligender company's website "does not recommend making any financial, emotional or family planning decisions based on the test results. This includes painting a nursery!"
And now for some more scientific methods:
16. Blood test
This can be done from about nine weeks and takes about a week to get the results. The pathologists search a sample of your blood for the baby’s DNA, which can also reveal the baby’s sex. The purpose of this test is more commonly used to check for Down Syndrome and other genetic conditions, so you may need to pay.
17 and 18. CVS or Amniocentesis testing
Chorionic villus sampling (which tests some of the placenta) can be done at 11 to 13 weeks. Amnio (which tests the amniotic fluid) can be done from 16 to 20 weeks. While these invasive procedures can predict the sex of a child with 99% accuracy, they both carry risk of miscarriage so are not recommended except to rule out genetic conditions.
The most reliable way is to video the little bugger and see if you can see what needs to be seen. But a word of warning, the kiddo may not co-operate by flashing and in rare cases it can be interpreted incorrectly. Ultrasound is usually done between 18 and 26 weeks and is a routine part of pre-natal medical testing.
Dr John Williams from Cedars-Sinai told CNN of ultrasounds, "If it's done by a skilled person... there's 90% to 95% certainty on gender."
When in doubt, wait till it’s out. That’s a pretty definite result one-way or the other. You have a 50% chance each pregnancy of having a boy!
And as a bonus...
Here is one more way to tell: the intriguing nub theory.