Effect of Delayed Cord Clamping on Systemic Blood Flow: A Randomized Controlled Trial

Delayed Cord Clamping for 45 Seconds in Very Low Birth Weight Infants: Impact on Hemoglobin at Birth and Close to Discharge

OBJECTIVES

To assess the impact of delayed cord clamping (DCC) for 45 seconds on hemoglobin at birth and close to discharge in very low birth weight (VLBW) infants and to compare modes of delivery in infants who received DCC.

STUDY DESIGN

In a retrospective study, 888 VLBW infants (≤1,500 g) who survived to discharge and received immediate cord clamping (ICC) were compared with infants who received DCC. Infants who received DCC and born via Cesarean section (C-section) were compared with those born via vaginal birth.

RESULTS

A total of 555 infants received ICC and 333 DCC. Only 188 out of 333 VLBW infants (56.5%) born during the DCC period received DCC. DCC was associated with higher hemoglobin at birth (15.9 vs. 14.9 g/dL, p = 0.001) and close to discharge (10.7 vs. 10.1 g/dL, p < 0.001) and reduced need for blood transfusion (39.4 vs. 54.9%, p < 0.001). In the DCC group, hemoglobin at birth and close to discharge was similar in infants born via C-section and vaginal birth.

CONCLUSION

DCC for 45 seconds increased hemoglobin at birth and close to discharge and reduced need for blood transfusion in VLBW infants. DCC for 45 seconds was equally effective for infants born by C-section and vaginal delivery. Approximately 44% of VLBW infants did not receive DCC even after implementing DCC guidelines.

KEY POINTS

· Studies to date have shown that DCC improves mortality and short- and long-term outcomes in VLBW infants.. · No consistent guidelines for the duration of DCC in preterm and term neonates.. · DCC for 45 seconds increased hemoglobin at birth and close to discharge in VLBW infants..

Deferred cord clamping and cord milking: Certainty and quality of the evidence in meta-analyses, and systematic reviews of randomized control trials, guidelines, and implementation studies

Deferred¹ cord clamping (DCC) saves lives, so why is it not implemented more routinely? Despite neonatal benefits, DCC is under-utilized, particularly in preterm births. Umbilical cord milking (UCM) also improves some outcomes for preterm infants such as decreasing the need for transfusions. At term, DCC and UCM improve hematological indices.

OBJECTIVE

The objective of this chapter is to examine the quality of evidence for both preterm and term DCC (and UCM), clinical practice guidelines and implementation issues.

METHODS

Key evidence, primarily from network meta-analyses, meta-analyses and systematic reviews on both preterm and term DCC (and UCM) from randomized clinical trials, clinical practice guidelines and implementation studies, are summarized through a lens of the certainty and quality of the evidence. Regarding the certainty of evidence, for network meta-analysis the Confidence in Network Meta-analysis tool was used, and for meta-analyses the Cochrane Risk of Bias tool and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) were used. Guideline quality was appraised with two tools: Appraisal of Guidelines for REsearch & Evaluation II (AGREE II) and AGREE-Recommendation EXcellence (AGREE-REX). Implementation study quality was evaluated using The Mixed Method Appraisal tool.

RESULTS

In a network meta-analysis of 56 RCTs of cord management strategies, DCC reduced the odds of mortality in preterm infants by 30% compared to immediate cord clamping (ICC), including in the subgroup of infants born before 33 weeks', both with a moderate confidence assessment using the Confidence in Network Meta-analysis tool. DCC reduced the odds of any intraventricular hemorrhage (IVH) by 30%, and the odds of red blood cell transfusion by more than 50%, both with high ratings on the Confidence in Network Meta-analysis. Umbilical Cord Milking (UCM) did not reduce mortality compared to ICC. In contrast to the benefits shown in preterm birth with DCC, a systematic review showed that at term, there were no mortality benefits and few benefits at all except for improved hematological indices. A systematic review of clinical practice guidelines demonstrated that all of them endorsed DCC for uncompromised preterm infants, and 11 more cautiously noted that cord milking might be considered when DCC was not feasible. However, only half (49%) of the recommendations in the guidelines on the optimal duration of DCC were supported by high-quality evidence per AGREE-II and AGREE-REX. Fewer than one in 10 statements (8%) cited a mortality benefit with DCC for preterm infants. Regarding the uptake of DCC, a systematic review of 18 studies on facilitators and barriers to implementation found that almost all (12 of the 14 studies) focused on strategies such as protocols, policy, or toolkits; additionally, 8 of 14 studies used didactic teaching sessions. Only 8 of 18 studies scored high on all four domains of the Mixed Method Appraisal tool.

CONCLUSIONS

Compared to ICC, DCC in preterm infants conferred significant benefits for mortality, IVH and red blood cell transfusion, with confidence ratings of moderate (mortality) or high. Although guidelines worldwide encouraged preterm (and term) DCC, the quality of the clinical practice guidelines had room for improvement; only half of the recommendations on the optimal duration of preterm DCC were supported by high-quality evidence. Most guidelines did not mention a mortality benefit with preterm DCC and lacked details on practical aspects of implementation. Among implementation studies, which have focused mainly on protocols, policies, toolkits or didactic teaching, quality also demonstrated an opportunity for improvement.

Hemodynamic Changes with Umbilical Cord Milking in Nonvigorous Newborns: A Randomized Cluster Cross-over Trial

OBJECTIVE

To assess the hemodynamic safety and efficacy of umbilical cord milking (UCM) compared with early cord clamping (ECC) in nonvigorous newborn infants enrolled in a large multicenter randomized cluster-crossover trial.

STUDY DESIGN

Two hundred twenty-seven nonvigorous term or near-term infants who were enrolled in the parent UCM vs ECC trial consented for this substudy. An echocardiogram was performed at 12 ± 6 hours of age by ultrasound technicians blinded to randomization. The primary outcome was left ventricular output (LVO). Prespecified secondary outcomes included measured superior vena cava (SVC) flow, right ventricular output (RVO), peak systolic strain, and peak systolic velocity by tissue Doppler examination of the RV lateral wall and the interventricular septum.

RESULTS

Nonvigorous infants receiving UCM had increased hemodynamic echocardiographic parameters as measured by higher LVO (225 ± 64 vs 187 ± 52 mL/kg/min; P < .001), RVO (284 ± 88 vs 222 ± 96 mL/kg/min; P < .001), and SVC flow (100 ± 36 vs 86 ± 40 mL/kg/min; P < .001) compared with the ECC group. Peak systolic strain was lower (-17 ± 3 vs -22 ± 3%; P < .001), but there was no difference in peak tissue Doppler flow (0.06 m/s [IQR, 0.05-0.07 m/s] vs 0.06 m/s [IQR, 0.05-0.08 m/s]).

CONCLUSIONS

UCM increased cardiac output (as measured by LVO) compared with ECC in nonvigorous newborns. Overall increases in measures of cerebral and pulmonary blood flow (as measured by SVC and RVO flow, respectively) may explain improved outcomes associated with UCM (less cardiorespiratory support at birth and fewer cases of moderate-to-severe hypoxic ischemic encephalopathy) among nonvigorous newborn infants.

Divergent effects of initial ventilation with delayed cord clamping on systemic and pulmonary arterial flows in the birth transition of preterm lambs

A current view that delayed cord clamping (DCC) results in greater haemodynamic stability at birth than immediate cord clamping (ICC) is based on comparison of DCC vs. ICC followed by an asphyxial (∼2 min) cord clamp-to-ventilation (CC-V) interval. More recent data suggest that relatively minor perinatal differences in heart rate and blood pressure fluctuations exist between DCC and ICC with a non-asphyxial (<45 s) CC-V interval, but it is unknown how ventricular output and central arterial blood flow effects of DCC compare with those of non-asphyxial ICC. Anaesthetized preterm fetal lambs instrumented with flow probes on major central arteries were ventilated for 97 (7) s (mean (SD)) before DCC at birth (n = 10), or underwent ICC 40 (6) s before ventilation (n = 10). Compared to ICC, initial ventilation and DCC was accompanied by (1) redistribution of a similar level of ascending aortic flow away from cephalic arteries and towards the aortic isthmus after ventilation; (2) a lower right ventricular output after cord clamping that was redistributed towards the lungs, thereby maintaining the absolute contribution of this output to a similar increase in pulmonary arterial flow after birth; and (3) a lower descending thoracic aortic flow after birth, related to a more rapid decline in phasic right-to-left ductal flow only partially offset by increased aortic isthmus flow. However, systemic arterial flows were similar between DCC and non-asphyxial ICC within 5 min after birth. These findings suggest that compared to non-asphyxial ICC, initial ventilation with DCC transiently redistributed central arterial flows, resulting in lower perinatal systemic arterial, but not pulmonary arterial, flows. KEY POINTS: A current view that delayed cord clamping (DCC) results in greater haemodynamic stability at birth than immediate cord clamping (ICC) is based on comparison of DCC vs. ICC with an asphyxial (∼2 min) cord clamp-to-ventilation (CC-V) interval. Recent data suggest that relatively minor perinatal differences in heart rate and blood pressure fluctuations exist between DCC and ICC with a non-asphyxial (<45 s) CC-V interval, but how central arterial blood flow effects of DCC compare with those of non-asphyxial ICC is unknown. Anaesthetized preterm fetal lambs instrumented with central arterial flow probes underwent initial ventilation for ∼90 s before DCC at birth, or ICC for ∼40 s before ventilation. Compared to non-asphyxial ICC, initial ventilation with DCC redistributed central blood flows, resulting in lower systemic, but not pulmonary, arterial flows during this period of transition. This flow redistribution was transitory, however, with systemic arterial flows similar between DCC and non-asphyxial ICC within minutes after birth.

Impact of Deferred Cord Clamping on Mortality and Severe Neurologic Injury in Twins Born at <30 Weeks of Gestation

OBJECTIVE

To determine whether deferred cord clamping (DCC) compared with early cord clamping (ECC) was associated with reduction in death and/or severe neurologic injury among twins born at <30 weeks of gestation.

STUDY DESIGN

We performed a retrospective cohort study including all liveborn twins of <30 weeks admitted to a tertiary-level neonatal intensive care unit (NICU) in Canada between 2015 and 2018 using the Canadian Neonatal/Preterm Birth Network database. We compared DCC ≥30 seconds vs ECC <30 seconds. Our primary outcome was a composite of death and/or severe neurologic injury (severe intraventricular hemorrhage grade III/IV and/or periventricular leukomalacia). Secondary outcomes included neonatal morbidity and health care utilization outcomes. We calculated aORs and β coefficients for categorical and continuous variables, along with 95% CI. Models were fitted with generalized estimated equations accounting for twin correlation.

RESULTS

We included 1597 twins (DCC, 624 [39.1%]; ECC, 973 [60.9%]). Death/severe neurologic injury occurred in 17.8% (n = 111) of twins who received DCC and in 21.7% (n = 211) of those who received ECC. The rate of death/severe neurologic injury did not differ significantly between the DCC and ECC groups (aOR 1.07; 95% CI, 0.78-1.47). DCC was associated with reduced blood transfusions (adjusted β coefficient, -0.49; 95% CI, -0.86 to -0.12) and NICU length of stay (adjusted β coefficient, -4.17; 95% CI, -8.15 to -0.19).

CONCLUSIONS

The primary composite outcome of death and/or severe neurologic injury did not differ between twins born at <30 weeks of gestation who received DCC and those who received ECC, but DCC was associated with some benefits.

Immediate vs delayed cord clamping in preterm infants: A systematic review and meta-analysis

To compare and evaluate the efficacy and safety of immediate cord clamping (ICC) and delayed cord clamping (DCC) in preterm infants. We performed a comprehensive and systematic meta-analysis of randomised controlled trials (RCTs) assessing ICC and DCC in preterm infants by searching PUBMED, EMBASE, Science Direct, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, and Wanfang Database (from inception to 30 September 2020). Summary odds ratios or mean differences with 95% confidence intervals were calculated using a fixed- or random-effect model. A total of 20 RCTs with 1807 preterm infants were included in the study. DCC provided more benefits in increasing the haematocrit and haemoglobin levels at 24 hours of life (%), thus reducing the incidence of anaemia, necrotising enterocolitis, length of hospital stay and mortality than when ICC was performed. No significant differences were found between ICC and DCC in terms of peak bilirubin level; need for blood transfusion, mechanical ventilation (MV) and phototherapy; duration of MV and phototherapy; and incidences of intraventricular haemorrhage, retinopathy of prematurity, patent ductus arteriosus, respiratory distress syndrome, sepsis, jaundice, polycythaemia, periventricular leukomalacia and bronchopulmonary dysplasia. DCC is a safe, beneficial and feasible intervention for preterm infants. However, rigorously designed and large-scale RCTs are necessary to identify the role and ideal timing of DCC.

Effects of delayed cord clamping in intrauterine growth-restricted neonates: a randomized controlled trial

The time of cord clamping in intrauterine growth-restricted (IUGR) neonates remains an area of uncertainty. This assessor-blinded randomized controlled trial compared the effects of delayed cord clamping (DCC) with early cord clamping (ECC) on the systemic blood flow (SBF) and cerebral hemodynamics in IUGR neonates of gestational age ≥28 weeks, not requiring resuscitation. Eligible newborns were randomized to DCC (cord clamping after 60 s; n=55) or ECC (cord clamping within 30 s; n=55) group immediately after delivery. The primary outcome variable was superior vena cava (SVC) blood flow at 24±2 h. The secondary outcome variables were right ventricular output (RVO), anterior cerebral artery (ACA) blood flow velocity (BFV), superior mesenteric artery (SMA)-BFV and venous hematocrit at 24±2 h, peak total serum bilirubin (TSB), incidences of polycythemia, intraventricular hemorrhage, respiratory distress, feeding intolerance, and necrotizing enterocolitis, outcome, duration of hospital stay, screening audiometry, and serum ferritin levels at the postnatal age of 3 months. Compared to ECC, DCC was associated with significantly higher SVC flow (101.22±21.02 and 81.27±19.12 mL/kg/min, in DCC and ECC groups, respectively; p<0.0001), and significantly increased RVO, SMA-BFV, venous hematocrit, and serum ferritin levels. Though peak TSB was significantly higher with DCC, duration of phototherapy was comparable. ACA-BFV, incidence of polycythemia, and other outcomes were comparable between the groups.Conclusions: DCC was a safe and beneficial intervention in IUGR infants with an improved SBF and SMA-BFV and an increased hematocrit and serum ferritin levels without higher incidences of polycythemia and requirement of phototherapy for significant hyperbilirubinemia.Trial registration: Clinical Trials Registry of India (CTRI/2019/05/018904) What is Known: • Delayed cord clamping (DCC) increases superior vena cava (SVC) blood flow in preterm neonates. • DCC increases hematocrit and serum ferritin in intrauterine growth-restricted (IUGR) neonates, but there may be an associated risk of polycythemia and neonatal hyperbilirubinemia. What is New: • DCC increases SVC blood flow, right ventricular output, superior mesenteric artery blood flow velocity, venous hematocrit, and serum ferritin in IUGR neonates. • Incidences of polycythemia and duration of phototherapy for significant neonatal hyperbilirubinemia do not increase with DCC.

A 3-armed multicenter randomized controlled trial: Placental Transfusion in Very Preterm Infants (PT-VPI)

Preterm infants constitute an important proportion of neonatal deaths and various complications, and very preterm infants (VPI) are more likely to develop severe complications, such as intraventricular hemorrhage (IVH), anemia, and sepsis. It has been confirmed that placental transfusion can supplement blood volume in infants and reduce preterm-associated complications, which is further conducive to the development of the nervous system and a better long-term prognosis. Based on these advantages, placental transfusion has been widely used in VPI. There are three main types of placental transfusion: delayed cord clamping (DCC), intact umbilical cord milking (I-UCM), and cut umbilical cord milking (C-UCM). However, the optimal method for PT-VPI remains controversial, and it is urgent to identify the best method of placental transfusion. We plan to fully evaluate the safety and effectiveness of these three placental transfusion methods in VPI in a 3-arm multicenter randomized controlled trial: Placental Transfusion in Very Preterm Infants (PT-VPI). Trial registration: chictr.org.cn, number ChiCTR2000030953.

The effect of umbilical cord milking on cerebral blood flow in very preterm infants: a randomized controlled study

OBJECTIVE

To compare the effect of umbilical cord milking (UCM) vs. early cord clamping (ECC) on cerebral blood flow (CBF).

METHOD

Preterm infants <31 weeks' gestation were randomized to receive UCM or ECC at birth. Blood flow velocities and resistive & pulsatility indices of middle and anterior cerebral arteries were measured at 4-6 and 10-12 h after birth as an estimate of CBF.

RESULTS

Randomization allocated 37 infants to UCM and 36 to ECC. Maternal and antenatal variables were similar. There were no significant differences between groups in middle or anterior CBF velocities and resistive indices at either study time point. CBF variables were not correlated with mean blood pressure, systemic blood flow, or intraventricular hemorrhage.

CONCLUSIONS

In very preterm infants, UCM compared with ECC was not shown to change CBF indices during the first 12 h of age or correlate with other hemodynamic measures or with intraventricular hemorrhage.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01487187.

Superior vena cava flow: Role, assessment and controversies in the management of perinatal perfusion

The superior vena cava (SVC) is a large vein responsible for the venous return of blood from structures located superior to the diaphragm. The flow in the SVC can be assessed with Doppler ultrasound and can be used as a proxy for cerebral perfusion. Early clinical research studies showed that low SVC flow, particularly if for a prolonged period, was associated with short term morbidity such as intraventricular hemorrhage, mortality, and poorer neurodevelopmental outcomes. However, these findings have not been consistently reported in more recent studies, and the role of SVC flow in early management and as a predictor of poor long-term neurodevelopment has been questioned. This paper provides an overview of SVC assessment, the expected range of findings, and reviews the role of SVC flow as a diagnostic and monitoring tool for the assessment of perinatal perfusion.

Autologous umbilical cord blood for red cell concentrate transfusion in preterm infants in the era of delayed cord clamping: An uncontrolled clinical trial

OBJECTIVE

To assess the utility of autologous umbilical cord blood (UCB) for red cell concentrate (RCC) transfusion in preterm infants.

METHODS

We recruited preterm infants born at ≤30 weeks' gestation or have an estimated fetal weight <1,200 g. We intended to perform delayed cord clamping (DCC) and to collect UCB following DCC. The quality parameters used included blood culture performed once, and biochemical and haematological parameters assessed weekly.

RESULTS

Of the 46 recruited neonates, DCC could be performed for 1 minute in 11 (23.9%) and for 30-59 seconds in 10 (21.7%) infants. The success rate of UCB collection was significantly lower in infants who underwent DCC for 1 minute (27%) compared to those who underwent DCC for 30-59 seconds (70%) or immediate cord clamping (72%) (p value 0.031). Twenty-five UCBs were stored after eliminating three that had positive culture. UCB had satisfactory quality for transfusion from day 3 (when blood culture report was available) to 14 (after which pH decreased to <6.5). Thirteen infants required 27 RCC transfusions. Autologous UCB could be used for only five (18.5%) transfusions.

CONCLUSION

The success rate of UCB collection after DCC for 1 minute is low. Autologous UCB meets less than one-fifth of transfusion requirements. Hence, autologous UCB transfusion is not a workable option in preterm infants.

Delivery room emergencies in critical congenital heart diseases

Transition from fetal to postnatal life is a complex process. Even in the absence of congenital heart disease, about 4-10% of newborns require some form of assistance in the delivery room. Neonates with complex congenital heart disease should be expected to require significant intervention and thus the resuscitation team must be well prepared for such a delivery. Prenatal assessment including fetal and maternal health in general and detailed information on fetal heart structure, function and hemodynamics in particular are crucial for planning the delivery and resuscitation. In addition, understanding the impact of cardiac structural anomaly and associated altered blood flow on early postnatal transition is essential for success of resuscitation in the delivery room. In this article, we will briefly review transitional circulation focusing on altered hemodynamics of the complex congenital heart diseases and then discuss the process of preparing for these high-risk deliveries. Finally, we will review the pathophysiology resulting from the cardiac structural anomaly with resultant altered fetal circulation and discuss delivery room management of specific critical congenital heart diseases.

Effect of timing of umbilical cord clamping and other strategies to influence placental transfusion at preterm birth on maternal and infant outcomes

BACKGROUND

Infants born preterm (before 37 weeks' gestation) have poorer outcomes than infants at term, particularly if born before 32 weeks. Early cord clamping has been standard practice over many years, and enables quick transfer of the infant to neonatal care. Delayed clamping allows blood flow between the placenta, umbilical cord and baby to continue, and may aid transition. Keeping baby at the mother's side enables neonatal care with the cord intact and this, along with delayed clamping, may improve outcomes. Umbilical cord milking (UCM) is proposed for increasing placental transfusion when immediate care for the preterm baby is needed. This Cochrane Review is a further update of a review first published in 2004 and updated in 2012.

OBJECTIVES

To assess the effects on infants born at less than 37 weeks' gestation, and their mothers of: 1) delayed cord clamping (DCC) compared with early cord clamping (ECC) both with immediate neonatal care after cord clamping; 2) DCC with immediate neonatal care with cord intact compared with ECC with immediate neonatal care after cord clamping; 3) DCC with immediate neonatal care after cord clamping compared with UCM; 4) UCM compared with ECC with immediate neonatal care after cord clamping.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (10 November 2017), and reference lists of retrieved studies. We updated the search in November 2018 and added nine new trial reports to the awaiting classification section to be assessed at the next update.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing delayed with early clamping of the umbilical cord (with immediate neonatal care after cord clamping or with cord intact) and UCM for births before 37 weeks' gestation. Quasi-RCTs were excluded.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. Random-effects are used in all meta-analyses. Review authors assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

This update includes forty-eight studies, involving 5721 babies and their mothers, with data available from 40 studies involving 4884 babies and their mothers. Babies were between 24 and 36+6 weeks' gestation at birth and multiple births were included. The data are mostly from high-income countries. Delayed clamping ranged between 30 to 180 seconds, with most studies delaying for 30 to 60 seconds. Early clamping was less than 30 seconds and often immediate. UCM was mostly before cord clamping but some were milked after cord clamping. We undertook subgroup analysis by gestation and type of intervention, and sensitivity analyses by low risk of selection and attrition bias.All studies were high risk for performance bias and many were unclear for other aspects of risk of bias. Certainty of the evidence using GRADE was mostly low, mainly due to imprecision and unclear risk of bias.Delayed cord clamping (DCC) versus early cord clamping (ECC) both with immediate neonatal care after cord clamping (25 studies, 3100 babies and their mothers)DCC probably reduces the number of babies who die before discharge compared with ECC (average risk ratio (aRR) 0.73, 95% confidence interval (CI) 0.54 to 0.98, 20 studies, 2680 babies (moderate certainty)).No studies reported on 'Death or neurodevelopmental impairment' in the early years'.DCC may make little or no difference to the number of babies with severe intraventricular haemorrhage (IVH grades 3 and 4) (aRR 0.94, 95% CI 0.63 to 1.39, 10 studies, 2058 babies, low certainty) but slightly reduces the number of babies with any grade IVH (aRR 0.83, 95% CI 0.70 to 0.99, 15 studies, 2333 babies, high certainty).DCC has little or no effect on chronic lung disease (CLD) (aRR 1.04, 95% CI 0.94 to 1.14, 6 studies, 1644 babies, high certainty).Due to insufficient data, we were unable to form conclusions regarding periventricular leukomalacia (PVL) (aRR 0.58, 95% CI 0.26 to 1.30, 4 studies, 1544 babies, low certainty) or maternal blood loss of 500 mL or greater (aRR 1.14, 95% CI 0.07 to 17.63, 2 studies, 180 women, very low certainty).We identified no important heterogeneity in subgroup or sensitivity analyses.Delayed cord clamping (DCC) with immediate neonatal care with cord intact versus early cord clamping (ECC) (one study, 276 babies and their mothers)There are insufficient data to be confident in our findings, but DCC with immediate neonatal care with cord intact may reduce the number of babies who die before discharge, although the data are also compatible with a slight increase in mortality, compared with ECC (aRR 0.47, 95% CI 0.20 to 1.11, 1 study, 270 babies, low certainty). DCC may also reduce the number of babies who die or have neurodevelopmental impairment in early years (aRR 0.61, 95% CI 0.39 to 0.96, 1 study, 218 babies, low certainty). There may be little or no difference in: severe IVH; all grades IVH; PVL; CLD; maternal blood loss ≥ 500 mL, assessed as low certainty mainly due to serious imprecision.Delayed cord clamping (DCC) with immediate neonatal care after cord clamping versus umbilical cord milking (UCM) (three studies, 322 babies and their mothers) and UCM versus early cord clamping (ECC) (11 studies, 1183 babies and their mothers)There are insufficient data for reliable conclusions about the comparative effects of UCM compared with delayed or early clamping (mostly low or very low certainty).

AUTHORS' CONCLUSIONS

Delayed, rather than early, cord clamping may reduce the risk of death before discharge for babies born preterm. There is insufficient evidence to show what duration of delay is best, one or several minutes, and therefore the optimum time to clamp the umbilical cord remains unclear. Whilst the current evidence supports not clamping the cord before 30 seconds at preterm births, future trials could compare different lengths of delay. Immediate neonatal care with the cord intact requires further study, and there are insufficient data on UCM.The nine new reports awaiting further classification may alter the conclusions of the review once assessed.

No. 347-Obstetric Management at Borderline Viability

OBJECTIVE

The primary objective of this guideline was to develop consensus statements to guide clinical practice and recommendations for obstetric management of a pregnancy at borderline viability, currently defined as prior to 25+6 weeks.

INTENDED USERS

Clinicians involved in the obstetric management of women whose fetus is at the borderline of viability.

TARGET POPULATION

Women presenting for possible birth at borderline viability.

EVIDENCE

This document presents a summary of the literature and a general consensus on the management of pregnancies at borderline viability, including maternal transfer and consultation, administration of antenatal corticosteroids and magnesium sulfate, fetal heart rate monitoring, and considerations in mode of delivery. Medline, EMBASE, and Cochrane databases were searched using the following keywords: extreme prematurity, borderline viability, preterm, pregnancy, antenatal corticosteroids, mode of delivery. The results were then studied, and relevant articles were reviewed. The references of the reviewed studies were also searched, as were documents citing pertinent studies. The evidence was then presented at a consensus meeting, and statements were developed.

VALIDATION METHODS

The content and recommendations were developed by the consensus group from the fields of Maternal-Fetal Medicine, Neonatology, Perinatal Nursing, Patient Advocacy, and Ethics. The quality of evidence was rated using criteria described in the Grading of Recommendations Assessment, Development and Evaluation methodology framework (reference 1). The Board of the Society of Obstetricians and Gynaecologists of Canada approved the final draft for publication.

METHODS

The quality of evidence was rated using the criteria described in the Grading of Recommendations, Assessment, Development, and Evaluation methodology framework. The interpretation of strong and weak recommendations is described later. The Summary of Findings is available upon request.

BENEFITS, HARMS, AND COSTS

A multidisciplinary approach should be used in counselling women and families at borderline viability. The impact of obstetric interventions in the improvement of neonatal outcomes is suggested in the literature, and if active resuscitation is intended, then active obstetric interventions should be considered.

GUIDELINE UPDATE

Evidence will be reviewed 5 years after publication to decide whether all or part of the guideline should be updated. However, if important new evidence is published prior to the 5-year cycle, the review process may be accelerated for a more rapid update of some recommendations.

SPONSORS

This guideline was developed with resources funded by the Society of Obstetricians and Gynaecologists of Canada and the Women and Babies Program at Sunnybrook Health Sciences Centre.

RECOMMENDATIONS

Associations of measures of systemic blood flow used in a randomized trial of delayed cord clamping in preterm infants

OBJECTIVE

To determine associations of low superior vena cava (SVC) flow (≤55 ml/kg/min) and low right ventricular output (RVO) (≤150 ml/kg/min) in preterm infants.

DESIGN/METHODS

An observational study in infants <30 weeks gestation randomized to receive immediate (<10 s) or delayed cord clamping (DCC) (≥60 s).

RESULTS

The study enrolled 265 infants with a mean (SD) gestation 28 (2) weeks. Eighty-six (33%) infants had low SVC flow and 81 (31%) infants had low RVO. In multivariate analysis, low SVC flow was associated with gestation; low RVO was associated with DCC, gender and 5-minute Apgar; whereas mean RVO was negatively associated with both FiO₂ and mean airway pressure (MAP) at 9 h and 24 h. Low SVC flow was associated with ductus arteriosus (DA) treatment. Infants with low RVO had higher mortality on univariate analysis, but this was not significant after adjusting for gestation.

CONCLUSIONS

SVC flow was associated with gestation, whilst RVO was associated with placental transfusion, gender, condition at birth, and early respiratory adaptation. Compared to infants with normal values, more infants with low SVC flow were treated for DA, but infants with low RVO had no significant difference in mortality or morbidity.

Cord milking versus immediate clamping in preterm infants: a randomised controlled trial

OBJECTIVE

To investigate whether umbilical cord milking (UCM) at birth improves systemic blood flow and short-term outcomes, as compared with immediate cord clamping (ICC).

DESIGN

Randomised clinical trial.

SETTING

Single tertiary care centre.

PATIENTS

Infants born to eligible women presenting in preterm labour between 24 and 31 weeks' gestation.

INTERVENTIONS

UCM three times at birth or ICC.

OUTCOME MEASURES

Primary outcome included systemic blood flow as represented by echo-derived superior vena cava(SVC) flow at 4-6 hours after birth. The echocardiographer and interpreter were blinded to the randomisation. Secondary outcomes included cardiac output, neonatal morbidities and mortality. Analysis was by intention to treat.

RESULTS

A total of 73 infants were randomised (37 to UCM and 36 to ICC). Mean (SD) gestational age was 27 (2) weeks and mean (SD) birth weight was 1040 (283) g. Haemoglobin on admission was higher in the UCM than in the ICC group (16.1 vs 15.0 g/L), p=0.049 (mean difference 1.1, 95% CI 0.003 to 2.2). No statistically significant differences were found between groups in SVC flow at 4-6 hours (88.9±37.8 and 107.3±60.1 mL/kg/min), p=0.13 (mean difference -18.4, 95% CI -41.7 to 5.0 mL/kg/min) or at 10-12 hours of age (102.5±41.8 and 90.6±28.4 mL/kg/min), p=0.17 (mean difference 12.0, 95% CI -4.7 to 28.7 mL/kg/min), cardiac output or neonatal morbidities.

CONCLUSIONS

Cord milking was not shown to improve functional cardiac outcomes, neonatal morbidity or mortality. More research is needed before routine cord milking can be recommended for very preterm infants.

TRIAL REGISTRATION

NCT01487187.

Transfusion or Timing: The Role of Blood Volume in Delayed Cord Clamping During the Cardiovascular Transition at Birth

Placental transfusion has been thought to be the main benefit of delayed umbilical cord clamping (DCC) in preterm neonates. However, the importance of cardiovascular stability provided by allowing lung aeration prior to cord clamping has recently been highlighted. We aimed to determine the influence of blood volume changes on cardiovascular stability at birth. Preterm lambs (0.85 gestation) were instrumented for measurement of pulmonary, systemic and cerebral blood pressures and flows, systemic oxygen saturation and cerebral oxygenation. Left ventricular output (LVO) was assessed by Doppler Echocardiography. Lambs underwent immediate cord clamping followed by (1) 25 ml/kg infusion of whole blood over (90 s; or 2) withdrawal of 10 ml/kg blood over 90 s. Ventilation was initiated 30 s after volume change (2 min after cord clamping) and was maintained for 30 min. Blood infusion significantly increased pulmonary blood flow (PBF) which maintained systemic cardiac output during the infusion, and increased carotid arterial pressure, flow and heart rate, which remained elevated until after ventilation onset. Upon completion of transfusion PBF rapidly returned to control levels and LVO decreased. Conversely, blood withdrawal decreased PBF and LVO. The cardiovascular changes that accompanied ventilation onset were similar between groups. Providing a blood volume transfusion immediately after umbilical cord clamping maintains PBF and cardiac output during the transfusion, which does not persist beyond the period of the transfusion. Our study implies that an apneic newborn cannot maintain cardiac output through an increase blood volume alone. Importantly, delaying umbilical cord clamping until after breathing/aeration of the lung may be a way to maintain cardiac output throughout delivery at birth.

Haemodynamic effects of umbilical cord milking in premature sheep during the neonatal transition

OBJECTIVE

Umbilical cord milking (UCM) at birth may benefit preterm infants, but the physiological effects of UCM are unknown. We compared the physiological effects of two UCM strategies with immediate umbilical cord clamping (UCC) and physiological-based cord clamping (PBCC) in preterm lambs.

METHODS

At 126 days' gestational age, fetal lambs were exteriorised, intubated and instrumented to measure umbilical, pulmonary and cerebral blood flows and arterial pressures. Lambs received either (1) UCM without placental refill (UCMwoPR); (2) UCM with placental refill (UCMwPR); (3) PBCC, whereby ventilation commenced prior to UCC; or (4) immediate UCC. UCM involved eight milks along a 10 cm length of cord, followed by UCC.

RESULTS

A net volume of blood was transferred into the lamb during UCMwPR (8.8 mL/kg, IQR 8-10, P=0.01) but not during UCMwoPR (0 mL/kg, IQR -2.8 to 1.7) or PBCC (1.1 mL/kg, IQR -1.3 to 4.3). UCM had no effect on pulmonary blood flow, but caused large fluctuations in mean carotid artery pressures (MBP) and blood flows (CABF). In UCMwoPR and UCMwPR lambs, MBP increased by 12%±1% and 8%±1% and CABF increased by 32%±2% and 15%±2%, respectively, with each milk. Cerebral oxygenation decreased the least in PBCC lambs (17%, IQR 13-26) compared with UCMwoPR (26%, IQR 23-25, P=0.03), UCMwPR (35%, IQR 27-44, P=0.02) and immediate UCC (34%, IQR 28-41, P=0.02) lambs.

CONCLUSIONS

UCMwoPR failed to provide placental transfusion, and UCM strategies caused considerable haemodynamic disturbance. UCM does not provide the same physiological benefits of PBCC. Further review of UCM is warranted before adoption into routine clinical practice.

Benefits of umbilical cord milking versus delayed cord clamping on neonatal outcomes in preterm infants: A systematic review and meta-analysis

BACKGROUND

Optimum timing of umbilical cord clamping has not been established in preterm infants.

OBJECTIVES

We compared the short- and long-term effects of umbilical cord milking (UCM) versus delayed cord clamping (DCC) on infants born at less than 37 weeks of gestation.

SEARCH METHODS

A systematic review and meta-analysis was conducted according to the "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" statement. We searched CINAHL, CENTRAL, EMBASE, MEDLINE, PubMed and ClinicalTrials.gov for relevant randomized controlled trials (RCTs).

SELECTION CRITERIA

We included individual and clustered RCTs comparing UCM to DCC for infants born before 37 weeks of gestation.

DATA COLLECTION AND ANALYSIS

Four reviewers independently assessed trial quality and eligibility for inclusion.

MAIN RESULTS

Two trials (255 preterm infants, 23 0/7 to 32 6/7 weeks of gestation) were included in the analysis. UCM was associated with fewer intraventricular hemorrhages (IVHs) (two trials, 255 infants; relative risk [RR] 0.45, 95% confidence interval [CI] 0.20 to 0.98, low quality of evidence) and UCM was an increased proportion of infants with a Bayley score at 2 years of age (two trials, 174 infants; Cognitive: RR 1.14, 95% CI 1.03 to 1.26, Language: RR 1.24, 95% CI 1.03 to 1.49, low quality of evidence) compared to DCC.

CONCLUSIONS

UCM wasn't reduced in-hospital mortality and need for transfusion compared to DCC. But our study suggests that UCM may lower the risk of IVH and improve certain neurodevelopmental outcomes compared to DCC in preterm infants.

Interobserver agreement and image quality of functional cardiac ultrasound measures used in a randomised trial of delayed cord clamping in preterm infants

OBJECTIVE

Functional cardiac ultrasound measures are used clinically and in trials for assessing the haemodynamic status of newborn infants. Superior vena cava (SVC) flow and right ventricular output (RVO) are established measures of systemic blood flow on the first postnatal day. The objective was to assess image quality and interobserver agreement of these measures in preterm infants enrolled in a randomised trial of immediate versus delayed cord clamping.

DESIGN AND SETTING

Image quality and interobserver agreement for SVC flow, RVO and ductus arteriosus (DA) size were assessed on measurements taken at 3-6, 6-12 and 20-28 hours for the first 10 infants enrolled at each of four sites (total 40). Bland-Altman plots were constructed; mean difference (bias) and limits of agreement (LOA) were calculated. Potential sources of variation were explored.

RESULTS

Quality was judged satisfactory for >97% of images. The mean difference and LOA between the observers were 5.4 mL/kg/min and -49.0 to 59.8 mL/kg/min for SVC flow, -26.6 mL/kg/min and -131.4 to 78.2 mL/kg/min for RVO, and 0 mm and -0.8 to 0.8 mm for DA diameter, respectively. The principal source of measurement error for SVC flow was diameter, and for RVO, diameter and velocity time integral. The difference between observers for both SVC and RVO was significantly associated with site.

CONCLUSION

Interobserver variability for SVC flow is consistent with that previously reported, but higher for RVO. The findings should be incorporated into clinical practice, training, accreditation and trial design.

Evaluating a Targeted Bedside Measure of Cerebral Perfusion in a Nonhuman Primate Model of Neonatal Hypoxic-Ischemic Encephalopathy

OBJECTIVES

To compare ultrasound-derived resistive indices (RIs) obtained at the level of the thalamus via fast Doppler ultrasound with traditional anterior cerebral artery measures in a model of neonatal hypoxic-ischemic encephalopathy and to correlate each with clinical outcomes.

METHODS

Nine nonhuman primate neonates underwent no umbilical cord occlusion (n = 3), umbilical cord occlusion without hypothermia (n = 3), or umbilical cord occlusion with hypothermia (n = 3). The RI was measured in the anterior cerebral artery and thalamus on days 0, 1, and 4 of life. Magnetic resonance imaging with spectroscopy was performed on day 4.

RESULTS

Mean thalamus and anterior cerebral artery RI values in the first 36 hours of life were statistically different in neonates who died (+0.13; P = .019) or developed cerebral palsy (-0.08; P = .003). Thalamic RI values showed stronger associations with serum and spectroscopic lactate values than those in the anterior cerebral artery. The umbilical cord occlusion-with-hypothermia group showed a significant increase in the RI in the thalamus but not the anterior cerebral artery.

CONCLUSIONS

Resistive index measurements in the thalamus may eventually supplement other bedside measures for predicting outcomes in the HIE population, but further studies need to differentiate the effect of hypothermia from illness severity on thalamic perfusion.

Placental Transfusion and Cardiovascular Instability in the Preterm Infant

Postnatal adaptation in preterm newborn comprises complex physiological processes that involve significant changes in the circulatory and respiratory system. Increasing hemoglobin level and blood volume following placental transfusion may be of importance in enhancing arterial oxygen content, increasing cardiac output, and improving oxygen delivery. The European consensus on resuscitation of preterm infants recommends delayed cord clamping (DCC) for at least 60 s to promote placenta-fetal transfusion in uncompromised neonates. Recently, published meta-analyses suggest that DCC is associated with fewer infants requiring transfusions for anemia, a lower incidence of intraventricular hemorrhage, and lower risk for necrotizing enterocolitis. Umbilical cord milking (UCM) has the potential to avoid some disadvantages associated with DCC including the increased risk of hypothermia or delay in commencing manual ventilation. UCM represents an active form of blood transfer from placenta to neonate and may have some advantages over DCC. Moreover, both methods are associated with improvement in hemodynamic parameters and blood pressure within first hours after delivery compared to immediate cord clamping. Placental transfusion appears to be beneficial for the preterm uncompromised infant. Further studies are needed to evaluate simultaneous placental transfusion with resuscitation of deteriorating neonates. It would be of great interest for future research to investigate advantages of this approach further and to assess its impact on neonatal outcomes, particularly in extremely preterm infants.

The Pathophysiology of Low Systemic Blood Flow in the Preterm Infant

Assessment and treatment of the VLBW infant with cardiovascular impairment requires understanding of the underlying physiology of the infant in transition. The situation is dynamic with changes occurring in systemic blood pressure, pulmonary pressures, myocardial function, and ductal shunt in the first postnatal days. New insights into the role of umbilical cord clamping in the transitional circulation have been provided by large clinical trials of early versus later cord clamping and a series of basic science reports describing the physiology in an animal model. Ultrasound assessment is invaluable in assessment of the physiology of the transition and can provide information about the size and shunt direction of the ductus arteriosus, the function of the myocardium and its filling as well as measurements of the cardiac output and an estimate of the state of peripheral vascular resistance. This information not only allows more specific treatment but it will often reduce the need for treatment.

Delayed vs early umbilical cord clamping for preterm infants: a systematic review and meta-analysis

BACKGROUND

The effects of delayed cord clamping of the umbilical cord in preterm infants are unclear.

OBJECTIVE

We sought to compare the effects of delayed vs early cord clamping on hospital mortality (primary outcome) and morbidity in preterm infants using Cochrane Collaboration neonatal review group methodology.

STUDY DESIGN

We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Chinese articles, cross-referencing citations, expert informants, and trial registries to July 31, 2017, for randomized controlled trials of delayed (≥30 seconds) vs early (<30 seconds) clamping in infants born <37 weeks' gestation. Before searching the literature, we specified that trials estimated to have cord milking in >20% of infants in any arm would be ineligible. Two reviewers independently selected studies, assessed bias, and extracted data. Relative risk (ie, risk ratio), risk difference, and mean difference with 95% confidence intervals were assessed by fixed effects models, heterogeneity by I² statistics, and the quality of evidence by Grading of Recommendations, Assessment, Development, and Evaluations.

RESULTS

Eighteen randomized controlled trials compared delayed vs early clamping in 2834 infants. Most infants allocated to have delayed clamping were assigned a delay of ≥60 seconds. Delayed clamping reduced hospital mortality (risk ratio, 0.68; 95% confidence interval, 0.52-0.90; risk difference, -0.03; 95% confidence interval, -0.05 to -0.01; P = .005; number needed to benefit, 33; 95% confidence interval, 20-100; Grading of Recommendations, Assessment, Development, and Evaluations = high, with I² = 0 indicating no heterogeneity). In 3 trials in 996 infants ≤28 weeks' gestation, delayed clamping reduced hospital mortality (risk ratio, 0.70; 95% confidence interval, 0.51-0.95; risk difference, -0.05; 95% confidence interval, -0.09 to -0.01; P = .02, number needed to benefit, 20; 95% confidence interval, 11-100; I² = 0). In subgroup analyses, delayed clamping reduced the incidence of low Apgar score at 1 minute, but not at 5 minutes, and did not reduce the incidence of intubation for resuscitation, admission temperature, mechanical ventilation, intraventricular hemorrhage, brain injury, chronic lung disease, patent ductus arteriosus, necrotizing enterocolitis, late onset sepsis or retinopathy of prematurity. Delayed clamping increased peak hematocrit by 2.73 percentage points (95% confidence interval, 1.94-3.52; P < .00001) and reduced the proportion of infants having blood transfusion by 10% (95% confidence interval, 6-13%; P < .00001). Potential harms of delayed clamping included polycythemia and hyperbilirubinemia.

CONCLUSION

This systematic review provides high-quality evidence that delayed clamping reduced hospital mortality, which supports current guidelines recommending delayed clamping in preterm infants. This review does not evaluate cord milking, which may also be of benefit. Analyses of individual patient data in these and other randomized controlled trials will be critically important in reliably evaluating important secondary outcomes.

Application of NPE in the assessment of a patent ductus arteriosus

In many preterm infants, the ductus arteriosus remains patent beyond the first few days of life. This prolonged patency is associated with numerous adverse outcomes, but the extent to which these adverse outcomes are attributable to the hemodynamic consequences of ductal patency, if at all, has not been established. Different treatment strategies have failed to improve short-term outcomes, with a paucity of data on the correct diagnostic and pathophysiological assessment of the patent ductus arteriosus (PDA) in association with long-term outcomes. Echocardiography is the selected method of choice for detecting a PDA, assessing the impact on the preterm circulation and monitoring treatment response. PDA in a preterm infant can result in pulmonary overcirculation and systemic hypoperfusion, Therefore, echocardiographic assessment should include evaluation of PDA characteristics, indices of pulmonary overcirculation with left heart loading conditions, and indices of systemic hypoperfusion. In this review, we provide an evidence-based overview of the current and emerging ultrasound measurements available to identify and monitor a PDA in the preterm infant. We offer indications and limitations for using Neonatologist Performed Echocardiography to optimize the management of a neonate with a PDA.

Delayed versus Immediate Cord Clamping in Preterm Infants

BACKGROUND

The preferred timing of umbilical-cord clamping in preterm infants is unclear.

METHODS

We randomly assigned fetuses from women who were expected to deliver before 30 weeks of gestation to either immediate clamping of the umbilical cord (≤10 seconds after delivery) or delayed clamping (≥60 seconds after delivery). The primary composite outcome was death or major morbidity (defined as severe brain injury on postnatal ultrasonography, severe retinopathy of prematurity, necrotizing enterocolitis, or late-onset sepsis) by 36 weeks of postmenstrual age. Analyses were performed on an intention-to-treat basis, accounting for multiple births.

RESULTS

Of 1634 fetuses that underwent randomization, 1566 were born alive before 30 weeks of gestation; of these, 782 were assigned to immediate cord clamping and 784 to delayed cord clamping. The median time between delivery and cord clamping was 5 seconds and 60 seconds in the respective groups. Complete data on the primary outcome were available for 1497 infants (95.6%). There was no significant difference in the incidence of the primary outcome between infants assigned to delayed clamping (37.0%) and those assigned to immediate clamping (37.2%) (relative risk, 1.00; 95% confidence interval, 0.88 to 1.13; P=0.96). The mortality was 6.4% in the delayed-clamping group and 9.0% in the immediate-clamping group (P=0.03 in unadjusted analyses; P=0.39 after post hoc adjustment for multiple secondary outcomes). There were no significant differences between the two groups in the incidences of chronic lung disease or other major morbidities.

CONCLUSIONS

Among preterm infants, delayed cord clamping did not result in a lower incidence of the combined outcome of death or major morbidity at 36 weeks of gestation than immediate cord clamping. (Funded by the Australian National Health and Medical Research Council [NHMRC] and the NHMRC Clinical Trials Centre; APTS Australian and New Zealand Clinical Trials Registry number, ACTRN12610000633088 .).