There's a new way to predict your baby's gender.

But it’s not pretty.

If you’re pregnant and revolted by formerly favourite foods — and most everything else for that matter — you may be carrying a boy, a new study suggests.

Polish researchers found that women carrying boy babies were more likely than those with girls to be squeamish in the first two trimesters of pregnancy, according to the study published in the journal Physiology and Behaviour.

The theory is that the squeamishness — or “disgust” to use the authors’ words — is there to protect growing male embryos, which other studies have shown to be more vulnerable than female ones, explains Agnieszka ?ela?niewicz and her co-author, both researchers in the department of human biology at the University of Wroc?aw, Poland. This feeling of disgust is something separate from pregnancy nausea, though they’re probably linked.

And while it might seem odd to still be trying to predict gender at a time when ultrasound can often provide an answer the burning question, there are plenty of couples who opt to eschew scanning but still like to play the guessing game, says OB-GYN Dr. Diana Bitner, a physician with the Spectrum Health Medical Group in Grand Rapids.

“There are couples who choose not to find out via ultrasound but want to have fun with it,” Bitner says, adding that we might call this new method “The Smelly Socks Test,” and append it to the long list of tried, if not altogether true, techniques to determine a baby’s sex before birth.

For example, there’s the high versus low method, which suggests that women carrying their babies low are having boys, and girls if they are carrying high. Interestingly, many horse breeders subscribe to a similar prediction method: if the mare carries wide, it’s a filly, if she carries low it’s a colt.

Another old time favourite, Bitner says, is the pendulum test. “You take a needle and tie it to a thread and hang it over the mum’s belly,” she explains. “If it turns clockwise it’s a girl, counter clockwise and it’s a boy.”

The researchers in the new study make the argument that a woman’s level of “disgust” is tied to the way her immune system functions while trying to protect her growing fetus. Squeamishness, ?ela?niewicz explains, is designed to protect the especially vulnerable male fetus by causing the expectant mum to stay away from sketchy substances.

To test their theory, the researchers rounded up 92 pregnant women and asked them during the first, second and third trimesters to fill out a questionnaire designed to test for disgust “sensitivity.” The women were asked to rate how revolted they were (on a scale of one to five) after reading various scenarios, that included, “You take a sip of soda and then realise that you drank from the glass that an acquaintance of yours had been drinking from,” and “It would really bother me to be in a science class and see a human hand preserved in a jar,” and “It would bother me to see a rat run across my path in a park.”

As it turned out, women carrying male fetuses were more easily disgusted during the first and second trimesters than those carrying girls.

Bitner isn’t convinced that “The Smelly Socks Test” is any better than what’s already out there. But she did find the researchers’ tie in with immunity theories intriguing.

What favourite food turned you off during your pregnancy?

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