Premature babies hiccup for up to 15 minutes a day and new research suggests that it's a mechanism that contributes to life-sustaining brain development.
Hiccups are characterised as abrupt and involuntary contractions of the diaphragm. Scientists from the department of Neuroscience, Physiology and Pharmacology at University College London say that they trigger electrical pulses in the brain which could assist babies with learning to regulate their breathing.
"The reasons for why we hiccup are not entirely clear, but there may be a developmental reason, given that fetuses and newborn babies hiccup so frequently," said Kimberley Whitehead, a research associate and lead study author. The research was published in the journal of Clinical Neurophysiology.
Researchers observed 13 newborn infants in a neonatal unit during bouts of hiccuping. The babies were ranged in gestational age from 30 to 42 weeks - both premature and full-term - so their development reflected usual hiccup patterns in the final trimester of pregnancy.
Brain activity readings via electrodes placed on the scalp worked in unison with movement sensors on the body.
The results indicated that, "... contractions of the diaphragm muscle from a hiccup evoked a pronounced response in the brain's cortex - two large brainwaves followed by a third. As the third brainwave is similar to that evoked by a noise, a newborn baby's brain may be able to link the 'hic' sound of the hiccup with the feel of the diaphragm muscle contraction."
Senior author, Dr Lorenzo Fabrizi said, "The activity resulting from a hiccup may be helping the baby's brain to learn how to monitor the breathing muscles so that eventually breathing can be voluntary controlled by moving the diaphragm up and down. When we are born, the circuits which process body sensations are not fully developed, so the establishment of such networks is a crucial developmental milestone for newborns."
As for why adults hiccup, Ms Whitehead suggested that they are simply a legacy behaviour from newborn days.
"Our findings have prompted us to wonder whether hiccups in adults, which appear to be mainly a nuisance, may in fact by a vestigial reflex, leftover from infancy when it had an important function."