## 5 Frequency Spectrum Analysis of FHR
### The Loss of Variability  
The experts' system computer diagnosed the loss of long term variability when the mean amplitude of LTV was \(<\)1 bpm. In addition, the loss of variability was diagnosed, if the La/Ta ratio \(<\) 15% and PPSD \(<\) 60 bpm\({}^{2}\)/Hz, in the frequency spectrum analysis of FHR baseline [7]. Since FHR variability developed by the response of fetal brain to minor fetal movements, the loss of FHR variability could be the sign of general damage of fetal brain. Thus, it would be recommended to perform rapid delivery, such as a cesarean section, before the loss of variability to reduce cerebral palsy [10; 11; 12], instead of cesarean section after the loss of variability. It was important, therefore, to alarm the states before the loss of variability, which would be reduced variability \(<\)5 bpm, severe bradycardia, severe late decelerations lasting \(>\)15 min, repeated severe variable decelerations, prolonged deceleration \(>\)2 min, loss of acceleration, high hypoxia index (sum of \(<\)110 bpm bradycardia duration (min) \(\times\) 100/nadir bradycardia) tentatively as 20-24 [12]. There will be institutions, which performed cesarean section by the signs before the loss of variability listed here with the purpose to improve perinatal state, and experienced the reduction of CP. That was natural according to the theory in the present report. **6. Central Computerized Automatic Fetal Monitoring System (TOITU Central Station Monitor MF-7400A20W) (Tokyo) [19]**  
_6.1. Data Input_  
FHR and uterine contraction signals were transferred by the local area network or radio wave telemetry to the central computer system, where the 100 channel time sharing system accepts multiple case signals in a non-fault computer system, preparing many simultaneous deliveries. There was no FHR chart recorder, instead original data are saved in a large memory to replay the FHR curve and output its hard copy on demand. The phone number of attending doctor was memorized in the data to inform the doctor of analyzed results. _6.2. Computer Processing_  
The central computer program was composed of an experts' knowledge system to determine the FHR score and detect FHR elements, and an artificial neural network system to output outcome probabilities to be normal, suspicious and pathologic. FHR frequency spectrum analysis reported the diagnosis of pathologic sinusoidal FHR and the loss of variability. _6.3. Direct Report to Attending Doctor_  
Pathologic results obtained by the computer system were immediately and directly reported to the attending doctor, responsible departments and on the electronic patient record, to perform various treatments for the prevention of fetal compromise, by cellular phone, PC or similar mobile data terminal using registered address at the input of fetal data. The contents of direct information are listed in Table 2.  
_6.4. Clinical Improvements by the Use of Centralized Computer System_  
Perinatal mortality was significantly reduced compared to the previous computer system without a rapid and direct reporting system, and no cerebral palsy developed, using the central fetal monitoring \begin{table}
\begin{tabular}{l} \hline \hline Bradycardia \(<\) 110, tachycardia \(>\) 180 (bpm) \({}^{\#}\), \\ Reduced FHR variability \(<\) 5 bpm \({}^{\#}\) \\ The loss of variability \({}^{\#}\) \\ Pathologic sinusoidal FHR \({}^{\#}\) \\ Loss of acceleration \\ Severe variable deceleration \({}^{\#}\) \\ Prolonged deceleration\(>\)2 min \({}^{\#}\) \\ Late decelerations \(>\) 15 min \({}^{\#}\) \\ FHR score \(>\)10 \({}^{\#}\) \\ Pathologic outcome probability \(>\)30\% \({}^{\#}\) \\ A/B ratio (sum of acceleration duration ratio/fetal movement burst duration) \(<\) 1.0 * \\ \hline \end{tabular}
\end{table} 
Table 2: Direct information items of fetal abnormalities to attending doctor. computer system of the present report, at Seirei Mikatahara hospital (Table 3) [19].