P07.01: Gender‐specific effect of umbilical ring constriction on Wharton's jelly of the umbilical cord

Abstract

Objective: To test the hypothesis that the umbilical ring constriction has a hemodynamic effect on the umbilical venous transmural pressure and thus on the development of Wharton’s jelly (WJ) in the second half of pregnancy. Methods: In a cross-sectional study of 283 low-risk pregnancies (20–40 weeks), the cross-sectional area of the umbilical cord, arteries and umbilical vein (UV) was measured in the fetal end of the cord using ultrasound. The average of ≥5 repeat measurements was entered into the statistics. The WJ area was calculated by subtracting the total vessel area from the umbilical cord area. The maximum time averaged blood velocity was recorded at the same site and at the umbilical ring in the abdominal wall. The increase of the blood velocity (calculated in percents) was used to express the degree of umbilical ring constriction. Regression models and standard deviation score was used for the statistical analysis. Results: Increasing degree of umbilical ring constriction was associated with decreasing WJ area in female fetuses (Slope: −0.287, P = 0.013, 95%CI −0.511; −0.063), but not in male (Slope: 0.153, P = 0.181, 95%CI −0.073; 0.379). Similarly, the umbilical cord area was affected in female fetuses (Slope: −0.281, P = 0.003, 95%CI −0.464; −0.098) but not in male (Slope: 0.059, P = 0.626, 95%CI −0.181; 0.299). An association between increasing degree of umbilical ring constriction was associated with decreasing UV cross sectional area (CSA) in males (Slope: −0.271, P = 0.015, 95%CI −0, 489; −0.053), but not in females (Slope: −0.027, P = 0.734, 95%CI −0.182; 0.128). Conclusion: Physiological umbilical ring constriction at the abdominal wall affects the umbilical cord CSA and the WJ formation in female but not male fetuses. In male fetuses the UV CSA decreases with increasing degree of umbilical ring constriction, but UV CSA seems unaffected. This implies that such a constriction exerts hemodynamic, gender specific effects on the cord.