Objectives: To investigate the association between the amount of Wharton's jelly (WJ) and the umbilical coiling index (UCI).
Methods: The subjects included 140 pregnant women in the 2nd or 3rd trimester. The antenatal UCI was calculated as the reciprocal of the distance between a pair of coils. The sonographic cross-sectional areas of the cord, arteries and vein were measured. The WJ area was calculated by subtracting areas of the total vessels from the cord.
Results: UCIs were significantly smaller and WJ areas were significantly greater in the 3rd trimester than in the 2nd trimester. No correlations were observed between the UCI and WJ area in both trimesters.
Conclusion: There is a reduction of the UCI during pregnancy. No direct correlations were found between the amount of WJ and UCI.