Nanogirl Michelle Dickinson: Scientists may have figured out why we hiccup but there's still no cure

The adult hiccup could just be a leftover reflex from our newborn life. Photo / 123Rf

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From drinking water from the far side of a glass to having somebody jump out and scare you, hiccup remedies are wide-ranging and often a little strange. While the reason why we hiccup might not be entirely clear, new research out this week suggests that hiccups in adults could just be a leftover reflex from when we were newborn babies learning to breathe for ourselves.

When you hiccup, a spasm in your diaphragm occurs, which forces air into your lungs. This causes your vocal cords to suddenly close which creates the "hic" sound of a hiccup. While some medical conditions can cause regular hiccups that need further investigation, for most of us, hiccups are so infrequent that we just find them humorous when they do occur.

Our first hiccup occurs way before we are born, with fetal ultrasound imaging showing hiccupping occurring in the womb as early as nine weeks into a pregnancy.

Newborn babies hiccup much more than adults and preterm infants born more than three weeks before their due date can spend 1 per cent of their time or a total of 15 minutes a day hiccupping.

To look into whether a baby's higher rate of hiccupping can help to explain their purpose, researchers from University College London carried out a study that scanned the brains of newborn babies while they were having a bout of hiccups. They placed EEG (electroencephalography) electrodes on the scalp of the babies and movement sensors on their torsos to help correlate the timing of a hiccup to the corresponding brainwave pattern it produced.

A total of 13 babies were studied ranging from preterm babies born at 30 weeks to full-term babies born at 42 weeks gestational age.

The scans showed that when a baby hiccupped, the physical contraction of the diaphragm muscle created a pronounced response in the cortex of the brain, resulting in two large brainwaves spikes followed by a third smaller one.

This smaller brainwave was found to be similar to ones produced by a noise, implying that the brain of a newborn baby might be able to link the "hic" sound of a hiccup to it feeling the muscle contraction of the diaphragm.

Previous research by the same scientists has suggested that the reason why babies kick in the womb could be to help them to create mental maps of their own bodies. Looking at the hiccup data they also believe that hiccups could be part of the same process used to mentally map parts of their internal body.

The study published in the journal Clinical Neurophysiology suggests that the sensory feedback to the brain from the muscle contractions of a large hiccup could help the early developing brain to form new brain circuits connecting the correct brain signals to the correct body part.

Their theory is that the physical hiccupping process could help babies learn how to detect and monitor their breathing muscles so that eventually they can voluntarily control them through brain signals that tell the diaphragm to move up and down. If true, then the adult hiccup could just be a leftover reflex from our newborn life.

We all get hiccups from time to time as do cats, dogs and horses. While this research isn't conclusive about why we get them, a five-year study involving 53 hospital patients with hiccups and a series of different treatments found that none of the commonly suggested techniques were effective in stopping them. Their conclusion was that the best thing to do is just carry on with your day and let them stop on their own, no scaring or bag breathing required.