From Kook Science

Amniomancy (from the Greek: ἀμνίον, amníon ["inner membrane round the foetus"] + μαντεία, manteia ["divination, soothsaying"]) is a method of divination conducted by inspection and interpretation of an amniotic sac, the membrane (caul) that in some instances of birthing are found to remain intact over the head and face of a newborn child. On the subject, A. E. Waite in The Occult Sciences (London: K. Paul, Trench, Trübner & Co., 1891), p. 127, relates that "the superstition was exceedingly simple and excessively silly, being simply an inspection of the colour which the membrane chanced to exhibit. A fortunate future was predicted for the possessor of a ruddy-tinted caul, and sinister omens were drawn from the presence of a livid hue."