Counting fetal hiccups using a fetal movement acceleration measurement recorder

Objective: To clarify the degree of fetal hiccup occurrence by using a fetal movement acceleration measurement recorder.

Methods: A total of 23 pregnant women recorded fetal movements weekly or biweekly between 28 and 39 gestational weeks at home with the recorder. Fetal hiccups were defined as regular sharp oscillations - which occurred at 2-4 second intervals, more than 15 times per minute - on the maternal abdomen. The duration and frequency of the hiccup bouts were counted. The data were classified into an early (28-33 weeks) gestational group and a late (34-39 weeks) group, and compared between the two.

Results: A total of 164 records were obtained, and the total time analyzed amounted to 1035 hours. The mean incidence of a fetal hiccup bout at an early group was 0.19 times per hour, and it decreased to 0.15 at a late group (p = 0.02). The durations of fetal hiccup bouts were 8.17 and 7.88 minutes at an early and a late group, respectively, with no significant difference (p = 0.64).

Conclusions: The duration of a fetal hiccup bout did not change after 28 gestational weeks; however, incidence slightly decreased from an early to a late group.