HeartSounds, Inc.

Electrocardiography (ECG) utilizes detection of electrical potential at a sensor on the surface of mother’s abdominal wall.  Problems include interference from maternal heart rate, movement, or cross detection of twin heart rates.  Clinicians frequently need to confirm the signal.

Doppler technology utilizes directed ultrasound to detect fetal heart rates.  It is the most common form of non-invasive monitoring.  Problems with the Doppler devices include a bulky profile, need for frequent repositioning, accuracy is dependent on precise placement and orientation, susceptible to movement, and risks associated with prolonged fetal exposure to low frequency radiation[1].

Invasive ECG monitoring involves the placement of electrodes trans-vaginally into the uterus where they are screwed into the fetal skin.  Drawbacks include an increased chance of infection and limited applicability.  It can only be used in the latter stages of delivery and is not an option for multiple gestation pregnancies nor HIV/virally infected patients.