[Sonographically detectable changes in placental structures in pregnancy. 4. Statistical comparison of the frequency distribution of placental stages 0-3 in newborn infants in a pregnancy of 37-42 weeks duration].

Among women with a duration of pregnancy between 37 and 42 gestational weeks procentual frequency, confidence intervals of O. Bunke, pounts of separability and areas of unsharpners were analysed. 1412 sonographical examinations were done in 645 pregnant women. Stage 0 was found statistically significant more frequent with error of probability alpha = 0.05 until the 30. week of pregnancy, stage 1 between the 21. and 36. week of pregnancy, stage 2 between the 33. and 36. gestational week and stage 3 in 37. and 38. week. Transformation (areas of unsharpness) from stage 0 to stage 1 occurs between the 24. and 32. gestational week, from stage 1 to stage 2 between the 31. and 34. week, from stage 2 to stage 3 between the 36. and 42. gestational week.