The umbilical cord thickness measured at 18-23 weeks of gestational age

To establish an umbilical cord thickness nomogram from anatomy ultrasound scans performed between 18 and 23 weeks of gestational age in singleton pregnancies, and compare it to two previously published nomograms.

In this retrospective cohort study of 1107 patients, a total of 650 singleton pregnancies were included. The umbilical cord diameter measurements were performed at the level of fetal abdominal wall insertion, and were correlated with gestational age (GA) and estimated fetal weight (EFW). Statistical analysis with non-parametric polynomial least squares regression analysis was performed.

A statistically significant correlation between umbilical cord diameter and GA (P<0001, r=0.399, 95% CI 0.331 to 0.464), and EFW (P<0001, r=0.420, 95% CI 0.353-0.483) was observed. A nomogram of umbilical cord thickness according to GA (y), and EFW (y'), was generated from the following equations:y=-51.30+5.367*x-0.1165*x(2) and y'=6.917+0.007233*x, respectively.

Our nomogram is in agreement with one of the previously published nomograms that also measured umbilical cord diameter at the level of the fetal abdominal umbilical cord insertion. Therefore, we recommend umbilical cord thickness to be measured in close proximity to the fetal abdominal wall, but no further than 0.5 cm away from the wall insertion.