Deferred Cord Clamping and Long-Term Neurodevelopmental Outcomes in Preterm Infants Born < 29 weeks Gestation in Southern Alberta

Abstract

Importance: Deferred cord clamping (DCC) is recommended for both term and preterm infants to reduce neonatal complications; however, evidence regarding its association with long-term neurodevelopment remains limited. Primary objective: To examine the impact of DCC compared with immediate cord clamping (ICC) on mortality and any neurodevelopmental impairment (NDI) at 18–24 and 36 months corrected age (CA) in preterm infants born before 29 weeks’ gestation. Design, setting, and participants: This retrospective cohort study included preterm infants (<29 weeks) admitted to neonatal intensive care unit between 1 January 2006, and 31 December 2011, comprised ICC group, and those born between 1 July 2012, and 31 December 2017, comprised DCC group. Neurodevelopmental assessments were conducted at 18–24 and 36 months corrected age. Results: Of 165 infants who received DCC, 153 and 145 had outcome data available at 18–24 and 36 months, respectively. Infants in the DCC group had slightly higher gestational age at birth and a greater proportion were small for gestational age status. Compared with ICC, DCC was associated with lower odds of sepsis, severe retinopathy of prematurity, fewer blood transfusions and shorter oxygen dependence. To obtain equivalent comparison groups, a propensity score–matched analysis was conducted with adjustments for multiple confounding variables. The odds (OR) of death or any NDI at 18–24 months was 1.09 (95% CI: 0.98–1.21, p = .096), and at 36 months CA was 1.18 (95% CI: 1.06–1.32, p = .003). Cognitive assessment was performed using the WPPSI-III during the ICC period and the WPPSI-IV during the DCC period. To maintain consistency by relying on a single assessment tool (WPPSI-IV), an additional analysis was undertaken among preterm infants who received ICC within the DCC period (July 1, 2012–December 31, 2017) and were evaluated at 36 months CA; this analysis yielded a propensity score–adjusted OR was 0.77 (95% CI: 0.64–0.90). Conclusions: In infants born before 29 weeks’ gestation, DCC was not associated with increased odds of death or NDI at 18–24 months, but by 36 months CA, it significantly reduced the risk of death or neurodevelopmental impairment.