In 35 two-hour recordings of fetal heart rate and fetal movements, 14 periods of fetal hiccups were present (1.2% of the recording time) with a median duration of 3.5 min (range 1 to 8 min). No specific relation to behavioural states or movement patterns could be identified. The hiccupping frequency varied from 10 to 21 per min. Within a hiccupping spell, the mean frequency decreased from 20 +/- 11 to 12 +/- 6.2 per min. A small but evident increase in baseline frequency was present during the hiccupping spells, independent from other movements performed by the fetus.