Why Do We Hiccup? A Study of Newborn Babies Offers a Clue

Hic! Everyone gets them, nobody asks for them, and they usually stop on their own. But why does the body do something so strange? For a long time there was no good answer. A study on newborn babies has given scientists a new idea.

What a hiccup actually is

Under your lungs sits a dome-shaped muscle called the diaphragm. It is the main muscle you use to breathe. During a hiccup, the diaphragm suddenly contracts on its own, pulling air in fast. A split second later, the opening between your vocal cords snaps shut. That quick stop of air is what makes the “hic” sound.

Hiccups start before birth

Hiccups are one of the earliest movements a baby makes. They begin in the womb at around 9 weeks of pregnancy. Babies born early hiccup a lot: an estimated 1% of their time, roughly 15 minutes a day.

The UCL study

In 2019, researchers at University College London recorded the brain activity of 13 newborn babies on a hospital ward, aged from 30 to 42 weeks of development. Small sensors on the babies’ bodies showed exactly when each hiccup happened.

Each hiccup triggered a clear response in the brain: two large brainwaves, followed by a third. The third wave looked similar to the brain’s reaction to a sound, which suggests the baby brain may be linking the “hic” with the feeling of the diaphragm moving.

The researchers think this may help a newborn’s brain learn how to sense and later control its breathing muscles. If that is right, adult hiccups could be a leftover reflex from a time when they had a real job to do.

What it does not tell us

The study was small and looked only at babies. It does not prove why adults hiccup, and it does not explain the many home remedies people swear by. Most hiccup bouts are harmless and go away by themselves.

Sources

• UCL News: Newborn baby hiccups could be key to brain development
• Whitehead et al. (2019), Clinical Neurophysiology

This article is for curiosity and learning only and is not medical advice.