The Lung Test is unnecessary when—
1. The umbilical cord has dropped off, and cicatrisation has followed.
2. Where food is found in the stomach.
3. Where there are evident signs of putrefaction in utero.
4. Also in the case of the birth of monsters, or where, from congenital malformation, the possibility of live birth is excluded.
Besides the hydrostatic test, the following have been proposed:
Ploucquet‘s Test.—This test is based on the relative weight of the lungs, before and after respiration, to that of the entire body of the child. The variations found in practice between the relative weights render the test worse than useless.
Absolute Weight of the Lungs.—This test consists in a comparison of the weight of the lungs before and after respiration, and it may be stated here that the lungs, prior to respiration, vary in weight from about 400 to 650 grains; but so much depends on the maturity or immaturity of the child, and degree of respiration, that, like the last, the test is unworthy of confidence.
Wredin‘s Test.—Dr. Wredin, of Petrograd, states that the gelatinous substance found in the middle ear of infants before birth, gradually disappears, to be replaced by air on the subsequent establishment of respiration. Wendt, of Leipzig, from an examination of 300 cases, declares that the gelatinous substance can only be expelled by the establishment of full respiration. The value of this test has been questioned, as some observers have found that in different cases intervals of from a few hours to five weeks have occurred, before the replacement of the gelatinous material by air.
Table Showing the Signs of
Maturity of Child At Birth