A hiccup is an involuntarymovement (spasm) of the diaphragm (the muscles at the base of the lungs). Thespasm is followed by rapid closure of the vocal cords, producing a distinctivesound. Hiccups often start for no apparent reason and usually disappear after afew minutes. Rarely, hiccups can last for days, weeks or months. Hiccups arecommon and normal in newborns and infants.