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With the objective of evaluating the functional maturation age and developmental disturbances we have previously introduced the fetal autonomic brain age score (fABAS) using 30 min fetal magnetocardiographic recordings (fMCG, Jena). The score is based on heart rate pattern indices that are related to universal principles of developmental biology. The present work aims at the validation of the fABAS methodology on 5 min recordings from an independent database (fMCG, Bochum).We found high agreement of fABAS obtained from Jena normal fetuses (5 min subsets, n =  364) and Bochum recordings (n =  322, normal fetuses). fABAS of 48 recordings from fetuses with intra-uterine growth restriction (IUGR, Bochum) was reduced in most of the cases, a result consistent with IUGR fetuses from Jena previously reported. fABAS calculated from 5 min snapshots only partly covers the accuracy when compared to fABAS from 30 min recordings. More precise diagnosis requires longer recordings.fABAS obtained from fMCG recordings is a strong candidate for standardized assessment of functional maturation age and developmental disturbances. Even 5 min recordings seem to be valuable for screening for maturation problems.

Background: Heart rate variability (HRV) is becoming increasingly important in the analysis of prepartal cardiotocography (CTG). Dawes and Redmann have developed a computer algorithm which can calculate short-term variability on the basis of CTG data. In dealing with artefacts, CTG monitors average heart rate values over several beats which makes the use of standard measures of HRV such as the root mean square of successive differences (RMSSD) inappropriate. Fetal magnetocardiography (FMCG) enables the registration of signals similar to the electrocardiogram and this permits the precise determination of heart beat duration and, in consequence, of measures of fetal HRV., Methods: In this study we applied both methods--CTG and FMCG--sequentially and simultaneously in healthy pregnancies. Fetal short-term HRV was estimated on the basis of RMSSD values for both methods., Results: The RMSSD values of the FMCG data were generally higher and showed a wider dynamic range than those of the CTG. The direct comparison of the simultaneously acquired data demonstrated that the data processing of the CTG signal leads to a suppression of essential aspects of short-term HRV., Conclusion: FMCG permits a substantially more differentiated examination of fetal HRV and offers new possibilities in the analysis of fetal cardiac activity.