Figure 4.

Linear correlation (r = correlation coefficient of Spearman) of the intra-observer ultrasonographic measurements: A. of the diameter of the umbilical cord (cord₁ and cord₃ are respectively the first and second measurements of observer 1); and B. of the cross-sectional area of the umbilical cord (area₁ and area₃ are respectively the first and second measurements of observer 1).