[A study on the relation among oxytocin challenge test, maternal serum estriol level and placental change (author's transl)].

FHR oxytocin challenge test (OCT), maternal serum estriol level, neonatal birth weight and placental findings were studied in 206 cases. 1) Maternal serum estriol levels were not always related to the results of OCTs. 2) In the cases of positive and equivocal OCTs, the birth weight and the placental weight were smaller than those in negative OCT cases. 3) Positive and equivocal OCTs were frequently related with calcification and infarction of the placentae. 4) Neonatal birth weight showed close relation to the placental weight, though insignificant relation to maternal serum estriol level was observed. 5) The frequency of positive and equivocal OCTs was high in the cases of right-posterior position of placenta, and low in the cases of left-anterior.