Early Breathing in Very Preterm Infants during Deferred Cord Clamping (DCC) Is Related to Gestational Age and Is Not Independently Associated with Important Neonatal Outcomes: A 5-Year Cohort Study

Abstract

Deferred cord clamping (DCC) has been associated with reduced mortality in preterm infants, and a period of at least 30 s has been recommended before clamping. However, preterm infants assessed as being in need of resuscitation have often had earlier cord clamping. In this study, we aimed to compare neonatal outcomes for preterm infants undergoing DCC who established early breathing movements compared to those who were not breathing. After a 5 yr recruitment period, we recently completed the ABC study, in which preterm infants <31 weeks undergoing 50 s of DCC who were not breathing by 15 s of age were randomised into two groups: one received intermittent positive pressure ventilation (IPPV) and the other was a standard group, which received no breathing support. The outcomes in the two groups were similar, and for the present analysis, the groups were combined. Infants in the ABC study were compared with the cohort excluded from the original ABC study because they were breathing by 15 s (called the Breathing Before Clamping or BBC group). There were significant differences in demographics between the ABC and BBC groups. Spontaneous preterm labour was more common in the BBC group, and these infants were more likely to be delivered vaginally. Gestational age and birth weight were significantly higher in the BBC group (p < 0.01). Soon after birth, Apgar scores were significantly higher in the BBC group, with a lower base deficit on first obtained blood gas, and a smaller proportion were intubated in the delivery room. Fewer BBC infants were hypothermic (<36.5 °C) on admission. Multivariate regression analysis indicated whether infants were breathing or not at 15 s of age was linked predominantly to gestation. Important neonatal outcomes and a composite of these outcomes (mortality, severe intraventricular haemorrhage, bronchopulmonary dysplasia) were not significantly different between the ABC and BBC groups (odds ratio for the composite outcome was 1.77 CI 0.84–3.76 corrected for gestation). For very preterm infants undergoing DCC, important neonatal outcomes were related to gestational age and not independently associated with early breathing. There was a small group (7% of total) who were deemed compromised at birth and did not undergo DCC. These infants had significantly worse neonatal outcomes.