Table 1.
Search strategy and criteria for the selection of eligible studies.
| Search strategy | |
|---|---|
| Search terms (including their synonyms and MeSH terms) were combined according to PICO: | |
| “fetus”, “fetal”, “pregnancy” AND “active”, “respiration”, “fetal movement”, “fetal behavioral state”, “sinus arrhythmia”, AND “entropy”, “heart rate variability”, “linear models”, “nonlinear dynamics”, “spectral”, “time domain”, “short-term variation”, “short-term variability”, “frequency analysis”, “fractals”, “magnetocardiography”, “electrocardiography”, “electrocardiogram”, “magnetocardiogram” |
|
| Eligibility criteria | |
| Inclusion criteria | |
| (1) Singleton uncomplicated pregnancies, before start of labor. (2) Fetal heart rate detection based on Electrocardiography (ECG) or Magnetocardiography (MCG). (3) Reporting on both moving and resting fetuses. (4) Time domain Standard Deviation of normal-to-normal intervals (SDNN), Root Mean Square of the Successive Differences (RMSSD), Spectral (Very low Frequency power (VLF), Low Frequency Power (LF), High Frequency power (HF), LF/HF, total power) and Entropy [Approximate Entropy (ApEN), Sample Entropy (SampEn)] analyses | |
| Exclusion criteria | |
| (1) Complicated pregnancies (2) Compromised fetuses (3) Fetal activity based only on Maternal Perception or Heart Rate Pattern (HRP) before 35 gestational weeks | |
| Time frame | |
| All years | |
| Language | |
| English | |
| Publication status | |
| Peer reviewed articles | |
| No animal studies | |