A new photogrammetric method to measure fetal breathing movements.

OBJECTIVE In most recent studies, fetal respiratory movements have been measured with real-time and Doppler echography. We describe an alternative approach using photogrammetry that provides more objective measurements. METHODS Respiratory movements were studied in 28 women with uncomplicated pregnancies of 30-38 weeks' gestation. Fetal echographic images were recorded on videotape and digitized to obtain coordinates of the reference point (midpoint on the anterior abdominal wall of the fetus between the xiphoid process and the insertion of the umbilical vessels) and generate graphic representations of fetal movements in the anterior abdomen. RESULTS The mean duration of a complete respiratory cycle was 1.194 s, the mean distance representing the extent of movement was 2.92 mm, the mean inspiratory velocity was 5.52 mm/s and the mean expiratory velocity was 5.06 mm/s. CONCLUSIONS Photogrammetric analysis of images obtained with real-time echography provided accurate measurements of fetal breathing movements.