The occurrence and significance of fetal breathing movements have been debated over the past 80 years. Ahlfeld's1 observations of maternal abdominal wall movement, felt to be representative of fetal breathing movements, were apparently disbelieved by his colleagues in the late 19th century. Throughout the years, fetal breathing movements have been observed in many species at cesarean section and were attributed to external or asphyxial stimuli.2 In the recent past, techniques of catheter placement and blood gas determinations have made possible evaluation of the status of the fetus engaged in breathing activity. A number of investigators involved in the study of fetal physiology have made prolonged and detailed observations of the fetus (especially the fetal lamb) in the exteriorized preparation, with the body temperature maintained and the umbilical circulation intact. If nonasphyxial fetal breathing occurred, it would seem that it would have been noted.3
Sir Joseph Barcroft4
Fox HE. Fetal Breathing Movements and Ultrasound. Am J Dis Child. 1976;130(2):127–129. doi:10.1001/archpedi.1976.02120030017002
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