Table of Contents:
Introduction: Upright or ambulatory birth
positions are favourable for fetal oxygenation. Studies of
fetal oxygenation with regard to maternal position require free
maternal mobility. Therefore, telemetry for a fetal sensor for
such investigations is a pre-requisite. Telemetry -if
technically feasible- could enable monitoring of fetal oxygen
partial pressure using an existing sensor without restricting
the mobility of the parturient woman. We have developed a
telemetry system for use with a fetal transcutaneous partial
oxygen pressure sensor (ttcpO2) and have studied effects of
maternal position and position changes during normal labour.
Methods and Patients: The monitoring system consists of three
parts: the telemetry unit with the ttcpO2 sensor to transmit
the tcpO2 and the heating output telemetrically, a modified CTG
monitor and a personal computer storing the measurements. All
data were plotted on the CTG recording paper and fed into a new
purpose-designed software, displaying fetal heart rate, the
uterine contraction intensity, ttcpO2 and the heating output.
Three labouring women, randomly and successively adopting
?classical birth positions? (supine or side
positions), sitting or vertical or walking position, were
studied. Results: Fetal heart rate, uterine contractions,
ttcpO2 and heating output are influenced by the birth positions
and by changes of the birth position. In the classical supine
and side position there seemed to be lower fetal oxygenation.
Sitting, standing and especially walking were more favourable.
Discussion: Telemetry is useful to study a possible clinical
benefit of individual birth positions.