Automatic balance for fetal weight studies.
An automatic balance was constructed of aluminum sheet, miniature ball bearings, and a strain gauge. The balance was capable of measuring 1 to 4 kg. with an accuracy of +/- 0.5 Gm. and a 95 per cent response time of less than 0.3 seconds. Fetuses of term ewes were exteriorized and weighed continuously for up to 3 hours. Rapid depletion of the ewe's blood volume led to a 10 to 24 per cent increase in estimated fetal blood volume. Fetal weight loss occurred regularly during reversible occlusion of the umbilical veins.
D000818:Animals; D001835:Body Weight; D005260:Female; D005333:Fetus / Q000502:physiology*; D011247:Pregnancy; D012039:Regional Blood Flow; D012756:Sheep; D014470:Umbilical Cord / Q000098:blood supply; D014894:Weights and Measures