P0719 - Delayed Cord Clamping versus Umbilical Cord Milking and In-Hospital Outcomes among Extremely Premature Infants in the Neonatal Research Network.

Background: Short-term outcomes after delayed cord clamping (DCC) vs. umbilical cord milking (UCM) have not been studied outside of clinical trials.

Objective: To compare in-hospital outcomes of DCC vs UCM among infants <29 weeks gestational age (GA).

Design/

Methods: Retrospective cohort study of infants 22 0/7-28 6/7 weeks GA born in a Eunice Kennedy Shriver NICHD Neonatal Research Network center from 1/1/16-12/31/18 exposed to DCC or UCM. Infants who had severe congenital anomalies, did not receive active treatment at delivery or were exposed to both DCC and UCM were excluded. Primary outcome: mortality or severe intraventricular hemorrhage (grade III or IV IVH) by 36 weeks postmenstrual age (PMA). Secondary outcomes: 1) mortality by 36 weeks PMA; 2) severe IVH by 36 weeks PMA; 3) any IVH or mortality by 36 weeks PMA; 4) a composite of mortality or major morbidity [severe brain injury (severe IVH, cystic periventricular leukomalacia, porencephalic cyst or ventriculomegaly), necrotizing enterocolitis ( >= Bell stage II), grade 3 bronchopulmonary dysplasia (requiring mechanical ventilation), late onset sepsis, and severe retinopathy of prematurity (stage 4 or greater). The risk adjusted effect on outcomes was determined by multivariable regression, incorporating risk factors for mortality identified a priori, significant confounders, and center as random effect. A prespecified, exploratory analysis evaluated severe IVH in two GA strata, 22-246/7 and 25-286/7 weeks.

Results: Of 1834 infants, 1402 (76.4%) were exposed to DCC and 432 (23.5%) to UCM. The median center rate of exposure to DCC was 96.5% (range 1.72% - 100%) and to UCM was 3.55% (range 0% – 98%). Maternal and neonatal characteristics differed between groups (Table 1). Rates of mortality or severe IVH at 36 weeks PMA were higher in the UCM exposed group (28.3% in UCM vs 19.0% in DCC), however, after risk adjustment this was not statistically different [aOR 1.41 (95% CI 0.91-2.2) p=0.13]. Differences in the rates of secondary outcomes did not reach statistical significance (Table 2). In the GA stratified analysis, UCM exposed infants had higher rates of severe IVH, which was clinically and statistically significant in the 25-286/7week group, 14.8% vs 7.3% [aOR 1.81 (95% CI 1.2-2.8) p =0.01]. There was a significant interaction [p=0.001] by GA between DCC or UCM and the composite mortality or major morbidity outcome.

Conclusion: Mortality or severe IVH differed by nine percentage points between infants exposed to DCC vs UCM, although it was not statistically significant. In a stratified analysis, infants in the older GA strata, 25-286/7 weeks GA exposed to UCM had significantly higher odds of severe IVH. Bivariate analysis suggested that the UCM exposed infants were sicker; however, the association seen between UCM and severe IVH is similar to the largest trial comparing DCC and UCM and favors DCC.