One old wives tale is based around using the baby's heart rate as a predictor for what gender they will be. Who knows just how this little idea came to pass, but it has been around for a very long time.

This theory states that if the fetal heart rate is above 140 beats per minute (BPM), then the baby is more likely to be a girl. If the heart rate is below 140 BPM then the chances are that the baby will be a boy. The issue is, of course, what if the baby's heart rate varies between 120-160 BPM? This is, after all, where the normal fetal heart rate commonly lies.

As far as using predictor tests go, this one's a pretty harmless one to try and reasonably convenient as well. Each time you go to your maternity care provider for an ante-natal check, they will listen to your baby's heart rate. This can be detected from around eight weeks gestation when your health care professional will use a hand held Doppler. You can ask them to count the number of BPM or do this yourself; just make sure you have a second hand on your watch for accuracy. ecommended purely for this reason unless there are genuine concerns about the baby inheriting a sex linked chromosomal condition or other complications

So, am I having a boy or a girl?

There may be some truth to the idea that this method offers an ideal opportunity for a little harmless chat in the middle of an otherwise routine ante-natal check up. Your weight, size, uterine growth, urine testing they're all pretty straightforward markers for how a pregnancy is progressing. So why not have a little fun just to break the monotony and see if you can both take a punt of whether you are having a boy or a girl? This is a harmless aside to what can otherwise be a fairly routine and predictable health assessment.

It also helps health professionals to build a rapport with the pregnant woman.

But does the heart rate test work? There is no existing evidence which supports a correlation between an unborn baby's heart rate and its gender. Although it seems like a cute idea and perhaps makes a little sense, there is no hard science to back it up. There have been several studies done which have examined if there is any connection. The answer? There simply is not.

However, this little technique is still widely touted as an urban myth and a sure way to determine if a boy or a girl is on their way. After all, there is around a 50% chance that the baby will be either a boy or a girl, so the odds are still pretty reasonable.

What does heart rate measure?

One of the benefits of doing scientific studies is that sometimes researchers discover an entirely new set of results. These can be very different to what they set out to find in the first place. And interestingly, this is what happened when they were looking for a correlation between fetal heart rate and gender. What was found instead was that there is a change in baby heart rate according to their gestational age. As the baby matures, the heart rate adjusts to its size.

Likewise, the more active the baby, the higher their heart rate will be. Just like us, during periods of inactivity and sleep, their heart rate tends to slow down. This is because any additional movement requires oxygen to supply the muscles.

Just be sure it's the heartbeat you're counting

During ante natal checks it is common for the maternity care provider to listen for the baby's heartbeat. But often, the umbilical cord can be heard pulsating rather than the actual heart beating. The cord makes more of a whooshing noise, but the heart is a clearer with a more defined sound like a steady thump, thump .

It can get really confusing if you're listening to both the cord and the heartbeat at the same time. Doing this also increases the likelihood that you'll think you're having a girl because you're counting more than just the heart beat.

If it sounds too good to be true it probably is

Heart rates are as individual as the baby and the circumstances of each mother's pregnancy. It makes perfect sense that on any given day a baby's heart rate will rise and fall according to what it is up to. It can also be influenced by the mother's activity level and how fast her own heart is beating. So be open-minded about using your baby's heart rate as a means of predicting its gender.

The only sure way to know what a baby's gender is is to wait and see when it is born. Even ultrasound does not offer a 100% guarantee of gender. The baby may have its legs crossed, be lying in a particular way or even the umbilical cord may be obscuring its genitals from clear view.

Chromosomal studies and amniocentesis are more accurate as a means of determining gender. However, they are not recommended purely for this reason unless there are genuine concerns about the baby inheriting a sex linked chromosomal condition or other complications