Results
The overall design of the uterine contraction monitoring tool consists of receiving signals, amplifying, filtering and sending them to smartphone applications. Below the block diagram, show this process (Figure 6) in which a signal will amplify after receiving from the body. Then, through suitable filters, the target signal is extracted and de-noised. Finally, data was extracted from an analog-to-digital converter and sent via Bluetooth.
The developed device is portable, has a low weight, and can detect uterine contractions without interfering with noise (Figure 7). The usability of the device is easy, so that three electrodes receive signals from the body. While sending signals, the LED, besides the Bluetooth icon, is flashing light. After analysis, contraction signals show on the smartphone. The battery of the device is chargeable and located behind the device.
Sample contraction signals received from the device are shown in Figure 8. For device tuning, applying devices by pregnant women is needed.
Table 1 shows the results of the device evaluation. Two criteria for the accuracy (RE) and repeatability (CV) of the device are calculated. The numbers in the table showed that they were acceptable.
The smartphone application was developed in several sections (Figure 9). It consists of a login section, a profile section includes age, pregnancy age in weeks, number of deliveries, and type of delivery includes cesarean or vaginal delivery in a previous pregnancy. Previous uterine contraction tests, start new session and help. Abnormal contractions are identified using strength, duration and frequency of contractions, but this is the difference between women with or without history of cesarean delivery. For preterm patterns, the application shows warning notifications to users.