A new study from the Hadassah Medical Organization examined the impact of “true knot” of the umbilical cord — a rare complication in which the cord forms a knot that can tighten and restrict blood flow to the fetus — has found that the condition is a strong indicator of perinatal deaths.

The study was led by Prof. Shay Porat and Drs. Doron Kabiri and Gilad Karavani of the Department of Obstetrics and Gynecology at Hadassah’s Ein Kerem Hospital in Jerusalem. They published their findings in the highly regarded journal, the Archives of Gynecology and Obstetrics.

The HMO researchers examine data from 139,458 deliveries between 2003 and 2017. Of these, 0.26 percent involved a true knot and formed the study group, while the remaining 99.74 percent served as the control group. Male fetuses, longer cords, and maternal risk factors like diabetes and smoking were found to more common in the true knot group.

Analysis of the data showed much higher rates of unfavorable outcomes among true knot cases, including lower Apgar scores and more admissions to the neonatal ICU. The addition of multiple cord loops to a true knot was found to further elevate these risks still further.

Most dramatically, perinatal death rates were found to be significantly higher in cases of true knot, reaching almost one in 20 (4.7%), compared to one in 500 (0.2%) when it was absent.

The study suggests that early detection—though challenging—and close monitoring, could help mitigate these risks, especially if multiple loops are present. In some cases, delivery before 37 weeks might prevent complications.

Read the full study in the Archives of Gynecology and Obstetrics.