Electrode-based Sensor for Non-invasive Fetal Heart Rate and EMG Monitoring With Improved Reliability

The majority of obstetric deliveries in the US undergo electronic monitoring and continuous
uterine activity and fetal heart rate (FHR) monitoring is the standard of care. Typically,
external transducers are employed, the reliability of which depends on their proper
positioning, which may be disturbed by patient or fetal movement. The tocodynamometer
(strain gauge, toco for short) provides frequency and timing of contractions, but requires
transmission of tension from the uterus to the sensor. Fetal heart rate is acquired with an
external Doppler ultrasound transducer. The reliability of this monitor depends on the
ability to obtain a window to the fetal heart.

In some patients, particularly the obese, the toco and ultrasound may fail to monitor
consistently. In others both transducers require frequent repositioning by the nursing
staff, and the Doppler may erroneously report maternal heart rate instead of fetal.

The alternative uterine activity monitor is an intrauterine pressure catheter (IUPC), which
is placed through the cervical os in the adequately dilated patient with ruptured membranes.
While this monitor usually provides a more reliable signal than the toco, as well as
quantitative information regarding intrauterine pressure, it is invasive and there is an
increased risk of infection. The alternative FHR monitor is via fetal scalp electrode (FSE),
which is applied transvaginally to the fetal presenting part, also requiring adequate
cervical dilation and ruptured membranes. While the FSE usually provides a more reliable
signal, it is similarly invasive and increases risk of infection.

Inclusion Criteria:

- Women between the ages of 18 and 50 years old

- >/= 34 weeks gestation

- Single viable fetus in cephalic presentation

Exclusion Criteria:

- Bleeding or uterine scarring