Fetal heart rate parameters of anencephalic fetuses according to gestational age.

Objective: To evaluate various fetal heart rate (FHR) parameters of anencephalic fetuses and to assess the effect of the fetal nervous system on FHR according to gestational age.

Study Design: The antepartum nonstress test was performed in 25 anencephalic fetuses. Each FHR parameter was analyzed using a computerized FHR analysis system for various gestational groups, and the results were compared with results from a normal control group (N = 25).

Results: The mean baseline FHR of anencephalic fetuses decreased with increasing gestational age, as in normal fetuses. FHR variability increased with increasing gestational age, as in normal fetuses.

Conclusion: In anencephalic fetuses, baseline FHR and FHR variability changed significantly with gestational age. These results suggest that the autonomic nervous system is more likely to be preserved than the central nervous system in anencephalic fetuses in spite of malformed or insufficient central nervous system.