- Initiation of human parturition. VI. Identification and quantification of progesterone metabolites produced by the components of human fetal membranes. Milewich, L., Gant, N.F., Schwarz, B.E., Prough, R.A., Chen, G.T., Athey, B., Macdonald, P.C. J. Clin. Endocrinol. Metab. (1977)