Physiological-based cord clamping in very preterm infants: the Aeration, Breathing, Clamping 3 (ABC3) trial-study protocol for a multicentre randomised controlled trial

Umbilical cord management in newborn resuscitation: a systematic review and meta-analysis

BACKGROUND

Evidence supporting the benefits of delayed cord clamping is increasing; however, there is no clear recommendation on cord management during newborn resuscitation. This study aimed to investigate the effects of resuscitation initiated with an intact umbilical cord, hypothesizing it is a safe stabilization procedure that improves neonatal outcomes.

METHODS

Systematic search was conducted in MEDLINE, Embase, CENTRAL, and Web of Science from inception to March 1, 2024. Eligible articles compared neonatal outcomes in newborns receiving initial stabilization steps before and after cord clamping.

RESULTS

Twelve studies met our inclusion criteria, with six RCTs included in the quantitative analysis. No statistically significant differences were found in delivery room parameters, in-hospital mortality, or neonatal outcomes between the examined groups. However, intact cord resuscitation group showed higher SpO2 at 5 min after birth compared to cord clamping prior to resuscitation group (MD 6.67%, 95% CI [-1.16%, 14.50%]). There were no significant differences in early complications of prematurity (NEC ≥ stage 2: RR 2.05, 95% CI [0.34, 12.30], IVH: RR 1.25, 95% CI [0.77, 2.00]).

CONCLUSION

Intact cord management during resuscitation appears to be a safe intervention; its effect on early complications of prematurity remains unclear. Further high-quality RCTs with larger patient numbers are urgently needed.

IMPACT

Initiating resuscitation with an intact umbilical cord appears to be a safe intervention for newborns. No statistically significant differences were found in delivery room parameters, in-hospital mortality, and neonatal outcomes between the examined groups. The utilization of specialized resuscitation trolleys appears to be promising to reduce the risk of intraventricular hemorrhage in preterm infants. Further high-quality RCTs with larger sample sizes are urgently needed to refine recommendations.

Revolutionizing Neonatal Care: A Comprehensive Review of Intact Cord Resuscitation in Newborns

Neonatal resuscitation is a critical procedure aimed at ensuring the successful transition of newborns from intrauterine to extrauterine life. Traditionally, this involves immediate clamping and cutting of the umbilical cord, but recent advances have introduced intact cord resuscitation (ICR) as an alternative approach. This review aims to comprehensively analyze ICR, exploring its evolution, scientific basis, and clinical evidence. It seeks to evaluate the benefits and challenges associated with ICR and assess its impact on neonatal outcomes compared to traditional practices. A thorough review of the literature was conducted, including historical perspectives on neonatal resuscitation, the physiological rationale behind ICR, and critical clinical studies and trials. Current guidelines and recommendations were also examined, along with technological advancements and practical implementation issues. Evidence indicates that ICR offers significant benefits, including improved blood volume, better cardiovascular stability, and reduced risk of anemia in newborns. Comparative studies suggest that ICR can enhance neonatal outcomes and support a smoother transition to extrauterine life. Despite these benefits, challenges related to implementation and adherence to new practices persist. ICR represents a promising advancement in neonatal care, potentially improving newborns' health outcomes. Continued research and refinement of guidelines are necessary to fully integrate ICR into standard practice and address existing implementation challenges. This review highlights the need for ongoing evaluation and adaptation of resuscitation practices to optimize neonatal health and care.

Physiological-Based Cord Clamping: When the Baby Is Ready for Clamping

BACKGROUND

The timing of cord clamping has become a focal point for neonatal caregivers due to the promising outcomes associated with delayed cord clamping, which is a simple and cost-effective method to enhance the survival and well-being of preterm infants. While initially the rationale behind delaying clamping was to facilitate increased placental transfusion, research has unveiled additional hemodynamic benefits.

SUMMARY

Experimental studies have demonstrated improved circulatory transition when clamping is postponed until the lungs are adequately aerated. This suggests that infants requiring assistance during the transition phase may benefit from stabilization while still attached to the cord. The Aeration, Breathing, and then Clamping (ABC) project aimed to translate these experimental findings into clinical practice.

KEY MESSAGE

In this review, we will discuss the insights gained and lessons learned from the project's implementation.

Physiological-based cord clamping stabilised cardiorespiratory parameters in very low birth weight infants

AIM

We investigated the influence of physiological-based cord clamping (PBCC) on cardiorespiratory stability in very low birth weight (VLBW) infants during the first 72 h of life.

METHODS

This retrospective study comprised VLBW infants born at <32 + 0 weeks of gestation and admitted to the neonatal intensive care unit of the Medical University of Graz, Austria, from December 2014 to April 2021. VLBW infants delivered with PBCC were matched by gestational age and birth weight to delayed cord clamping controls. The PBCC group was stabilised after birth with an intact cord. Routine monitoring parameters were compared between the groups.

RESULTS

We included 54 VLBW infants. The mean gestational ages of the PBCC group and controls were 27.4 ± 1.9 versus 27.4 ± 1.8 weeks (p = 0.87), and the mean birth weights were 912 ± 288 versus 915 ± 285 g (p = 0.96), respectively. The mean cord clamping time was 191 ± 78 s in the PBCC group. Heart rate was lower in the PBCC group during the first 3 days after birth, reaching significance by 10 h. Other monitoring parameters did not reveal any differences between the two groups.

CONCLUSION

PBCC stabilised cardiorespiratory parameters in VLBW infants. The lower heart rate in the PBCC group suggested higher blood volume following intact cord resuscitation.

Ventilatory Assistance Before Umbilical Cord Clamping in Extremely Preterm Infants: A Randomized Clinical Trial

Importance

Providing assisted ventilation during delayed umbilical cord clamping may improve outcomes for extremely preterm infants.

Objective

To determine whether assisted ventilation in extremely preterm infants (23 0/7 to 28 6/7 weeks' gestational age [GA]) followed by cord clamping reduces intraventricular hemorrhage (IVH) or early death.

Design, Setting, and Participants

This phase 3, 1:1, parallel-stratified randomized clinical trial conducted at 12 perinatal centers across the US and Canada from September 2, 2016, through February 21, 2023, assessed IVH and early death outcomes of extremely preterm infants randomized to receive 120 seconds of assisted ventilation followed by cord clamping vs delayed cord clamping for 30 to 60 seconds with ventilatory assistance afterward. Two analysis cohorts, not breathing well and breathing well, were specified a priori based on assessment of breathing 30 seconds after birth.

Intervention

After birth, all infants received stimulation and suctioning if needed. From 30 to 120 seconds, infants randomized to the intervention received continuous positive airway pressure if breathing well or positive-pressure ventilation if not, with cord clamping at 120 seconds. Control infants received 30 to 60 seconds of delayed cord clamping followed by standard resuscitation.

Main Outcomes and Measures

The primary outcome was any grade IVH on head ultrasonography or death before day 7. Interpretation by site radiologists was confirmed by independent radiologists, all masked to study group. To estimate the association between study group and outcome, data were analyzed using the stratified Cochran-Mantel-Haenszel test for relative risk (RR), with associations summarized by point estimates and 95% CIs.

Results

Of 1110 women who consented to participate, 548 were randomized and delivered infants at GA less than 29 weeks. A total of 570 eligible infants were enrolled (median [IQR] GA, 26.6 [24.9-27.7] weeks; 297 male [52.1%]). Intraventricular hemorrhage or death occurred in 34.9% (97 of 278) of infants in the intervention group and 32.5% (95 of 292) in the control group (adjusted RR, 1.02; 95% CI, 0.81-1.27). In the prespecified not-breathing-well cohort (47.5% [271 of 570]; median [IQR] GA, 26.0 [24.7-27.4] weeks; 152 male [56.1%]), IVH or death occurred in 38.7% (58 of 150) of infants in the intervention group and 43.0% (52 of 121) in the control group (RR, 0.91; 95% CI, 0.68-1.21). There was no evidence of differences in death, severe brain injury, or major morbidities between the intervention and control groups in either breathing cohort.

Conclusions and Relevance

This study did not show that providing assisted ventilation before cord clamping in extremely preterm infants reduces IVH or early death. Additional study around the feasibility, safety, and efficacy of assisted ventilation before cord clamping may provide additional insight.

Trial Registration

ClinicalTrials.gov Identifier: NCT02742454.

Thermoregulation for very preterm infants in the delivery room: a narrative review

Abnormal temperature in preterm infants is associated with increased morbidity and mortality. Infants born prematurely are at risk of abnormal temperature immediately after birth in the delivery room (DR). The World Health Organization (WHO) recommends that the temperature of newly born infants is maintained between 36.5-37.5oC after birth. When caring for very preterm infants, the International Liaison Committee on Resuscitation (ILCOR) recommends using a combination of interventions to prevent heat loss. While hypothermia remains prevalent, efforts to prevent it have increased the incidence of hyperthermia, which may also be harmful. Delayed cord clamping (DCC) for preterm infants has been recommended by ILCOR since 2015. Little is known about the effect of timing of DCC on temperature, nor have there been specific recommendations for thermal care before DCC. This review article focuses on the current evidence and recommendations for thermal care in the DR, and considers thermoregulation in the context of emerging interventions and future research directions. IMPACT: Abnormal temperature is common amongst very preterm infants after birth, and is an independent risk factor for mortality. The current guidelines recommend a combination of interventions to prevent heat loss after birth. Despite this, abnormal temperature is still a problem, across all climates and economies. New and emerging delivery room practice (i.e., delayed cord clamping, mobile resuscitation trolleys, early skin to skin care) may have an effect on infant temperature. This article reviews the current evidence and recommendations, and considers future research directions.

Physiological-based cord clamping in very preterm infants: the Aeration, Breathing, Clamping 3 (ABC3) trial-statistical analysis plan for a multicenter randomized controlled trial

BACKGROUND

Mortality, cerebral injury, and necrotizing enterocolitis (NEC) are common complications of very preterm birth. An important risk factor for these complications is hemodynamic instability. Pre-clinical studies suggest that the timing of umbilical cord clamping affects hemodynamic stability during transition. Standard care is time-based cord clamping (TBCC), with clamping irrespective of lung aeration. It is unknown whether delaying cord clamping until lung aeration and ventilation have been established (physiological-based cord clamping, PBCC) is more beneficial. This document describes the statistical analyses for the ABC3 trial, which aims to assess the efficacy and safety of PBCC, compared to TBCC.

METHODS

The ABC3 trial is a multicenter, randomized trial investigating PBCC (intervention) versus TBCC (control) in very preterm infants. The trial is ethically approved. Preterm infants born before 30 weeks of gestation are randomized after parental informed consent. The primary outcome is intact survival, defined as the composite of survival without major cerebral injury and/or NEC. Secondary short-term outcomes are co-morbidities and adverse events assessed during NICU admission, parental reported outcomes, and long-term neurodevelopmental outcomes assessed at a corrected age of 2 years. To test the hypothesis that PBCC increases intact survival, a logistic regression model will be estimated using generalized estimating equations (accounting for correlation between siblings and observations in the same center) with treatment and gestational age as predictors. This plan is written and submitted without knowledge of the data.

DISCUSSION

The findings of this trial will provide evidence for future clinical guidelines on optimal cord clamping management at birth.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03808051. Registered on 17 January 2019.

Deferred cord clamping, cord milking, and immediate cord clamping at preterm birth: a systematic review and individual participant data meta-analysis

BACKGROUND

Umbilical cord clamping strategies at preterm birth have the potential to affect important health outcomes. The aim of this study was to compare the effectiveness of deferred cord clamping, umbilical cord milking, and immediate cord clamping in reducing neonatal mortality and morbidity at preterm birth.

METHODS

We conducted a systematic review and individual participant data meta-analysis. We searched medical databases and trial registries (from database inception until Feb 24, 2022; updated June 6, 2023) for randomised controlled trials comparing deferred (also known as delayed) cord clamping, cord milking, and immediate cord clamping for preterm births (<37 weeks' gestation). Quasi-randomised or cluster-randomised trials were excluded. Authors of eligible studies were invited to join the iCOMP collaboration and share individual participant data. All data were checked, harmonised, re-coded, and assessed for risk of bias following prespecified criteria. The primary outcome was death before hospital discharge. We performed intention-to-treat one-stage individual participant data meta-analyses accounting for heterogeneity to examine treatment effects overall and in prespecified subgroup analyses. Certainty of evidence was assessed with Grading of Recommendations Assessment, Development, and Evaluation. This study is registered with PROSPERO, CRD42019136640.

FINDINGS

We identified 2369 records, of which 48 randomised trials provided individual participant data and were eligible for our primary analysis. We included individual participant data on 6367 infants (3303 [55%] male, 2667 [45%] female, two intersex, and 395 missing data). Deferred cord clamping, compared with immediate cord clamping, reduced death before discharge (odds ratio [OR] 0·68 [95% CI 0·51-0·91], high-certainty evidence, 20 studies, n=3260, 232 deaths). For umbilical cord milking compared with immediate cord clamping, no clear evidence was found of a difference in death before discharge (OR 0·73 [0·44-1·20], low certainty, 18 studies, n=1561, 74 deaths). Similarly, for umbilical cord milking compared with deferred cord clamping, no clear evidence was found of a difference in death before discharge (0·95 [0·59-1·53], low certainty, 12 studies, n=1303, 93 deaths). We found no evidence of subgroup differences for the primary outcome, including by gestational age, type of delivery, multiple birth, study year, and perinatal mortality.

INTERPRETATION

This study provides high-certainty evidence that deferred cord clamping, compared with immediate cord clamping, reduces death before discharge in preterm infants. This effect appears to be consistent across several participant-level and trial-level subgroups. These results will inform international treatment recommendations.

FUNDING

Australian National Health and Medical Research Council.

Short, medium, and long deferral of umbilical cord clamping compared with umbilical cord milking and immediate clamping at preterm birth: a systematic review and network meta-analysis with individual participant data

BACKGROUND

Deferred (also known as delayed) cord clamping can improve survival of infants born preterm (before 37 weeks of gestation), but the optimal duration of deferral remains unclear. We conducted a systematic review and individual participant data network meta-analysis with the aim of comparing the effectiveness of umbilical cord clamping strategies with different timings of clamping or with cord milking for preterm infants.

METHODS

We searched medical databases and trial registries from inception until Feb 24, 2022 (updated June 6, 2023) for randomised controlled trials comparing cord clamping strategies for preterm infants. Individual participant data were harmonised and assessed for risk of bias and quality. Interventions were grouped into immediate clamping, short deferral (≥15 s to <45 s), medium deferral (≥45 s to <120 s), long deferral (≥120 s), and intact cord milking. The primary outcome was death before hospital discharge. We calculated one-stage, intention-to-treat Bayesian random-effects individual participant data network meta-analysis. This study was registered with PROSPERO, CRD42019136640.

FINDINGS

We included individual participant data from 47 trials with 6094 participants. Of all interventions, long deferral reduced death before discharge the most (compared with immediate clamping; odds ratio 0·31 [95% credibility interval] 0·11-0·80; moderate certainty). The risk of bias was low for 10 (33%) of 30 trials, 14 (47%) had some concerns, and 6 (20%) were rated as having a high risk of bias. Heterogeneity was low, with no indication of inconsistency.

INTERPRETATION

This study found that long deferral of clamping leads to reduced odds of death before discharge in preterm infants. In infants assessed as requiring immediate resuscitation, this finding might only be generalisable if there are provisions for such care with the cord intact. These results are based on thoroughly cleaned and checked individual participant data and can inform future guidelines and practice.

FUNDING

Australian National Health and Medical Research Council.

Maternal implications of placental transfusion

Placental transfusion for 30-60 s after delivery is recommended by numerous professional societies and is now a common practice. Numerous studies document neonatal benefit with minimal maternal risk when routine neonatal stabilization and active management of the third stage of labor are undertaken during the period of delayed cord clamping. Maternal outcomes do not show any increased incidence of postpartum hemorrhage, or need for blood product transfusion in the case of vaginal delivery or cesarean section. Fetomaternal hemorrhage is also likely decreased with delayed cord clamping. In the case of fetal anomalies, cord management should be individualized according to each special circumstance, but is unlikely to lead to increased maternal morbidity. While few studies have investigated maternal outcomes with umbilical cord milking, this practice has not been as widely adopted. With careful monitoring of maternal and fetal well-being, a period of placental transfusion following delivery is advised for benefit of the neonate without significant maternal risk.

The Respiratory Management of the Extreme Preterm in the Delivery Room

The fetal-to-neonatal transition poses an extraordinary challenge for extremely low birth weight (ELBW) infants, and postnatal stabilization in the delivery room (DR) remains challenging. The initiation of air respiration and the establishment of a functional residual capacity are essential and often require ventilatory support and oxygen supplementation. In recent years, there has been a tendency towards the soft-landing strategy and, subsequently, non-invasive positive pressure ventilation has been generally recommended by international guidelines as the first option for stabilizing ELBW in the delivery room. On the other hand, supplementation with oxygen is another cornerstone of the postnatal stabilization of ELBW infants. To date, the conundrum concerning the optimal initial inspired fraction of oxygen, target saturations in the first golden minutes, and oxygen titration to achieve desired stability saturation and heart rate values has not yet been solved. Moreover, the retardation of cord clamping together with the initiation of ventilation with the patent cord (physiologic-based cord clamping) have added additional complexity to this puzzle. In the present review, we critically address these relevant topics related to fetal-to-neonatal transitional respiratory physiology, ventilatory stabilization, and oxygenation of ELBW infants in the delivery room based on current evidence and the most recent guidelines for newborn stabilization.