Table 4.
The information on the data collection of the above-mentioned papers.
| Ref | Data | Gestational Period | Participants | Experimental Setup |
|---|---|---|---|---|
| [7] | Maternal ECG, SCG, FECG, EHG | Between 25 and 41 weeks | 576 | Daily regular activities |
| [20] | Maternal and fetal ECG | 20, 25, and 30 weeks | Not mentioned | Recordings were carried out in a private room. The time period was 30 s and repeated 5 times. |
| [24] | FCTG, FHR | Not mentioned | 10 | The subjects were required to stay in the supine position, seated position, and standing position. Five minutes for each position. |
| [21] | FHR | 38.5 weeks | Not mentioned | The system has been tested on both prenatal and laboring patients. |
| [22] | MECG, FECG, and fetal QRS complex | 37 weeks | 3 | The experiment protocol consists of 3 steps. (1) Supine situation for four minutes, (2) sitting position for two minutes, (3) standing posture for two minutes. The experiment is designed in a home-like laboratory environment. |
| [23] | FHR | >12 weeks | 4 | There were two stages. (1) a set of measurements was obtained by employing PPG sensors of light-based technology, (2) results were verified with a professional cardiograph (golden standard) |