# Labour diagnostics using the intrauterine pressure through sound waves emitted by a smartphone

## TL;DR

This paper explores using sound waves from a smartphone to measure intrauterine pressure for diagnosing labor onset, aiming to provide a low-cost and accessible alternative.

## Contribution

The study introduces a novel method for estimating intrauterine pressure using sound wave reflections from a smartphone.

## Key findings

- A 3D-printed model showed a positive linear correlation between reflection coefficients and internal pressure.
- 20 kHz frequency was found to be more effective than 4 kHz for pressure measurement due to lower error and non-audible properties.
- Reflection coefficients plateaued at shorter distances, indicating material limitations at specific frequencies.

## Abstract

Labour commencement diagnosis is still challenging in obstetrics. The majority of scientific techniques that were used to determine labour are costly and require a professional healthcare personnel to be carried out. Hence, in this work, an experiment was conducted using a 3D-printed 50% scale model of the abdomen of an average 40-week pregnant woman. The aim was to test whether the internal pressure can be evaluated from the reflection of the sound waves emitted by a smartphone. Frequencies of 4 kHz and 20 kHz were triggered at multiple distances (0.17, 0.34, 0.51 m) after inflating the 3D-printed model with water. The reflection coefficients and internal pressure were determined to have a positive linear correlation, suggesting that the hypothesis is practical. However, as the distances decreased, the reflection coefficient plateaued, indicating that the material had attained its maximum reflection coefficient at that frequency. Due to its reduced error and non-audible properties as compared to 4Hz, 20 kHz was suggested to be an optimum frequency for measuring pressure, allowing it for pain-free application for an extended amount of time.