Delaying umbilical cord clamping in preterm infants delivered prior to 30 weeks of gestation shows no significant difference in death or severe morbidity rates compared with immediate cord clamping when monitored 36 weeks postmenstrual age, according to a study in the New England Journal of Medicine.

William Tarnow-Mordi, MB, ChB, of the National Health and Medical Research Council Clinical Trials Center at the University of Sydney, and his associates conducted an unblinded, controlled, and randomized study for the Australian Placental Transfusion Study Collaborative Group (APTS) to compare the effects of cord clamping time with major health complications in preterm infants.

In this study, conducted from December 2010 until May 2017, the researchers differentiated delayed vs immediate clamping by calculating the time between birth and actual clamping of the umbilical cord.  Of the 1634 randomized early expectant fetuses, 1566 (95.8%) were categorized into either delayed (784 patients) or immediate cord clamping (782 patients). Stillborn infants were not included in the final analysis.

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Clamping time occurring for delayed and immediate actions was categorized as ≥60 seconds and ≤10 seconds, respectively. Median times were calculated as 60 seconds for delayed and 5 seconds for immediate. Medical concerns regarding patient health as well as improper implementation limited the accuracy of the times recorded in the study (94.9% rate of adherence).

Patients were tested for mortality or severe morbidity (primary outcome) to the brain seen via postnatal ultrasonography, critical retinopathy, necrotizing enterocolitis, or late-onset sepsis (diagnosis occurred after 36 weeks of postmenstrual age).

After 36 completed weeks, the previous outlines for morbidity and death were used to test patients further for late cerebral defects (shown in ultrasonography), intraventricular hemorrhage, and treated patent ductus arteriosus (secondary outcome).

A tertiary outcome test monitored weight at birth, red blood cell (RBC) transfusions by 36 weeks, infant temperature, primary week peak bilirubin and hematocrit levels, duration of hospital stay (for live discharged patients only), uterotonic drug usages, and maternal blood transfusion for postpartum hemorrhage, all of which resulted in statistically insignificant data.

Delayed cord clamping proved to have no major difference in levels of death (delayed, 6.4%; immediate, 9.0%). Morbidity in all three outcomes showed no statistical significance between the two groups (primary outcome relative risk, 1.00; secondary outcome relative rise, 0.69).

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The investigators theorized that the disconnect from previous studies, which suggested that delayed clamping was less harmful than immediate, might be due to the range in severity of illness between previous patients and those in this study. They plan to continue their research with the patients during childhood development.

“Discrepancies between past and current evidence might be explained if the infants in APTS were less severely ill than earlier cohorts.”


Tarnow-Modi W, Morris J, Kirby A, Robledo K, Askie L, Brown R, et al. Delayed versus immediate cord clamping in preterm infants. N Engl J Med. 2017 Oct 29. doi:10.1056/NEJMoa1711281