Effect of delayed cord clamping on very preterm twins

Effect of Placental Transfusion on Long-Term Neurodevelopmental Outcomes in Premature Infants: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

The pathophysiology and the potential risks of placental transfusion (PT) differ substantially in preterm infants, necessitating specific studies in this population. This study aimed to evaluate the safety and efficacy of PT in preterm infants from the perspective of long-term neurodevelopmental outcomes.

METHODS

We conducted a systematic literature search using placental transfusion, preterm infant, and its synonyms as search terms. Cochrane Central Register of Controlled Trials, Medline, and Embase were searched until March 07, 2023. Two reviewers independently identified, extracted relevant randomized controlled trials, and appraised the risk of bias. The extracted studies were included in the meta-analysis of long-term neurodevelopmental clinical outcomes using fixed-effects models.

RESULTS

A total of 5612 articles were identified, and seven randomized controlled trials involving 2551 infants were included in our meta-analysis. Compared with immediate cord clamping (ICC), PT may not impact adverse neurodevelopment events. No clear evidence was found of a difference in the risk of neurodevelopmental impairment (risk ratio [RR]: 0.89, 95% confidence interval [CI]: 0.76 to 1.03, P = 0.13, I2 = 0). PT was not associated with the incidence of cerebral palsy (RR: 1.23, 95% CI: 0.59 to 2.57, P = 0.79, I2 = 0). Analyses showed no differences between the two interventions in cognitive, language, and motor domains of neurodevelopment.

CONCLUSIONS

From the perspective of long-term neurodevelopment, PT at preterm birth may be as safe as ICC. Future studies should focus on standardized, high-quality clinical trials and individual participant data to optimize cord management strategies for preterm infants after birth.

Comparing two different placental transfusion strategies for very preterm infants at birth: a matched-pairs study

OBJECTIVE

To evaluate the clinical outcomes of using the extra-uterine placental transfusion (EPT) approach in very preterm infants (VPIs, gestational age <32 weeks) and compare this to delayed cord clamping (DCC) after birth.

METHODS

In this matched pairs study, we compared the clinical outcomes of the EPT group to those of the DCC group. EPT were performed in fifty-three VPIs, of whom 27 were singletons and 25 were twins. The singleton VPIs were matched for gestational age (±5 days) and delivery mode, and the twin VPIs were matched between each other with the first twin subjected to DCC and the second twin to EPT. Data on the infants were collected and analysed as an overall group. A twin subgroup consisting of DCC and EPT groups was also analysed separately. The primary study outcome was either death or major morbidities.

RESULTS

In total, 100 infants were included (n = 50 EPT group, n = 50 DCC group). The gestational ages of the DCC and EPT groups were (29.16 ± 1.76) and (29.12 ± 1.84) weeks, respectively. There were no differences in either deaths or major morbidities and other clinical outcomes, including the resuscitation variables, haemoglobin levels and red blood cell transfusion, between the two groups. In twin subgroups (gestational age 29.05 ± 1.89 weeks), EPT was associated with a higher rate of necrotizing enterocolitis (NEC) when compared with DCC (odds ratio = 7 (95% CI, 1.06 to 56.89), p = 0.031).

CONCLUSIONS

In twin subgroups, the incidence of NEC was higher in the EPT group when compared to the DCC group and therefore based on an abundance of caution the use of EPT in very preterm twins is not recommended.

Delayed versus immediate cord clamping in dichorionic twins <32 weeks: a retrospective study

OBJECTIVES

Strong evidence imply that delayed cord clamping (DCC) provides significant benefits for singleton neonates. However, there is little information about the safety or efficacy of DCC in twins to recommend for or against DCC in twins in guidelines. We aimed to determine the effect of DCC on dichorionic twins born at <32 weeks of gestation.

STUDY DESIGN

This is a retrospective cohort study comparing the neonatal and maternal outcomes of immediate cord clamping (ICC) [<15 second (s)] versus DCC (at 60 s). Generalized estimating equations models were performed accounting for twin correlation.

RESULTS

A total of 82 pairs of twins (DCC: 41; ICC: 41) were included in analysis. The primary outcome of death before discharge occurred in 3.66% of twins in the DCC group and 7.32% in the ICC group, without a significant difference between the groups. Compared to ICC group, DCC was associated with increased hemoglobin levels [β1 coefficient 6.51; 95% confidence interval (CI) 0.69-12.32. β2 coefficient 5.80; 95% CI 0.07-11.54] at 12-24 h of life. There were no significant differences between the groups in neonatal death, neonatal major morbidities and maternal bleeding complications, although DCC was associated with higher estimated maternal blood loss in the cesarean section group (p = .005).

CONCLUSIONS

DCC for 60 s in dichorionic twins born at <32 weeks of gestation was associated with increased neonatal hemoglobin levels, when compared with ICC. The finding of a higher estimated maternal blood loss by cesarean section in the DCC group calls for further trials to assess maternal safety of this procedure in this patient population.

Effect of delayed cord clamping on maternal and neonatal outcome in twin pregnancies: a retrospective cohort study

The objective of this study was to compare the maternal and neonatal outcomes following delayed cord clamping (DCC) versus immediate cord clamping (ICC) in twin pregnancies. This was a retrospective cohort study of 705 twin pregnancies who delivered at ≥ 24 weeks of gestation. Maternal and neonatal hemoglobin levels, blood transfusion, and neonatal outcomes were compared between DCC (n = 225) and ICC (n = 480) groups. Mean maternal predelivery and postpartum hemoglobin levels and the rate of postpartum hemoglobin drop ≥ 20% or maternal blood transfusion were comparable between the two groups. The DCC group had a significantly higher mean neonatal hemoglobin level (DCC vs. ICC: 17.4 ± 3.5 vs. 16.6 ± 2.7 g/dl, P = 0.010) but significantly lower rates of neonatal blood transfusion (DCC vs. ICC: 3.3% vs. 8.8%, P < 0.001) and respiratory distress syndrome (DCC vs. ICC: 6.7% vs. 15.2%, P < 0.001) than the ICC group. In conclusion, DCC compared with ICC in twin pregnancy was not associated with an increase of maternal postpartum bleeding complications, but it was associated with higher neonatal hemoglobin level and lower risks of neonatal blood transfusion and respiratory distress syndrome.

Assisted ventilation prior to umbilical cord clamping: Potential benefits, challenges, and research studies

Delayed cord clamping (DCC) is beneficial for many infants, and the American College of Obstetrics and Gynecology recommends at least 30-60 seconds of DCC for both term and preterm vigorous infants. For newly born infants that are not vigorous, some evidence in animal models suggests that providing assisted ventilation prior to cord clamping (V-DCC) leads to a more stable transition of cerebral, pulmonary and systemic circulation and oxygenation and may confer not only short-term physiologic benefits but perhaps also improvement in clinically important outcomes. This review is based around 7 questions to help the reader understand the physiologic underpinnings and challenges of V-DCC as well as the published and ongoing research studies aimed at determining whether V-DCC is beneficial for preterm or term infants.

Cord management strategies in multifetal gestational births

Multifetal gestations are associated with high risks of neonatal mortality and morbidities primarily due to prematurity. Delayed cord clamping and cord milking facilitate the postnatal transition and improve outcomes. Limited evidence shows that delayed cord clamping for 30-60 s and cord milking are feasible without causing harm and potentially beneficial in uncomplicated multifetal deliveries. However, data on maternal bleeding from the limited studies are inconsistent. Based on current knowledge of the risk vs. benefits, it is reasonable to perform delayed cord clamping or cord milking (>28 weeks of gestation) in uncomplicated monochorionic and dichorionic multiples. Clearly defined criteria for suitable candidates, indications for clamping or milking the cord during delivery, and improved obstetric techniques in Cesarean deliveries are critical to minimize risks and optimize neonatal transition. Research is needed to identify safe and optimal cord-management strategies for improving survival and long-term outcomes in this high-risk population.

Effects of Placental Transfusion on Late Preterm Infants Admitted to a Mother-Baby Unit

OBJECTIVE

Well-appearing late preterm infants admitted to a mother baby unit may benefit from either delayed cord clamping (DCC) or umbilical cord milking (UCM). However, there are concerns of adverse effects of increased blood volume such as polycythemia and hyperbilirubinemia. The purpose of this study is to examine the short-term effects of placental transfusion on late preterm infants born between 35^0/7 and 36^6/7 weeks of gestation.

STUDY DESIGN

In this pre- and postimplementation retrospective cohort study, we compared late preterm infants who received placental transfusion (161 infants, DCC/UCM group) during a 2-year period after guideline implementation (postimplementation period: August 1, 2017, to July 31, 2019) to infants who had immediate cord clamping (118 infants, ICC group) born during a 2-year period before implementation (preimplementation period: August 1, 2015, to July 31, 2017).

RESULTS

The mean hematocrit after birth was significantly higher in the DCC/UCM group. Fewer infants had a hematocrit <40% after birth in the DCC/UCM group compared with the ICC group. The incidence of hyperbilirubinemia needing phototherapy, neonatal intensive care unit (NICU) admissions, or readmissions to the hospital for phototherapy was similar between the groups. Fewer infants in the DCC/UCM group were admitted to the NICU primarily for respiratory distress. Symptomatic polycythemia did not occur in either group. Median hospital length of stay was 3 days for both groups.

CONCLUSION

Placental transfusion (DCC or UCM) in late preterm infants admitted to a mother baby unit was not associated with increased incidence of hyperbilirubinemia needing phototherapy, symptomatic polycythemia, NICU admissions, or readmissions to the hospital for phototherapy.

KEY POINTS

· Placental transfusion was feasible in late preterm infants.. · Placental transfusion resulted in higher mean hematocrit after birth.. · Placental transfusion did not increase the need for phototherapy.. · Fewer admissions to the NICU for respiratory distress were noted in the placental transfusion group..

The effects of placental transfusion on mothers

OBJECTIVE

While there is ample evidence supporting delayed cord clamping (DCC) in neonates, the data on the maternal outcomes related to DCC are relatively sparse. Moreover, the outcomes, such as postpartum hemorrhage (PPH), were mostly reported for uncomplicated term vaginal deliveries. The objective of this study was to present the two primary maternal outcomes, incidence of PPH and change in hematocrit pre- and post-delivery in complex situations of preterm deliveries and term cesarean sections.

STUDY DESIGN

Maternal data were collected prospectively since the placental transfusion process was implemented in a step-wise fashion in our delivery hospitals, starting August, 2013. These data on very preterm singleton, moderate preterm, very preterm twin gestation, late preterm deliveries and term cesarean sections with DCC or umbilical cord milking (UCM) were compared with respective retrospective cohorts of deliveries in which immediate cord clamping (ICC) was performed.

RESULTS

Comparing very preterm singleton deliveries, the incidence of PPH was similar between the ICC and DCC groups (2.3% vs. 1.7%). There was no significant difference in mean hematocrit change pre- and postdelivery (3.06 ± 1.32 vs. 3.47 ± 1.52). When 45 s DCC cohort was compared with 60 s DCC cohort, there were no significant differences in the incidence of PPH (1.7% vs. 4.8%) or the hematocrit change pre- and postdelivery (3.47 ± 1.52 vs. 4.32 ± 1.88). PPH was not observed in either group when comparing retrospective ICC cohort with prospective DCC cohort with 60 s delay in very preterm twin gestation deliveries. There was no significant difference between the mean hematocrit change pre- and postdelivery (5.5 ± 3.3 vs. 5.8 ± 3.9). When moderate and early late preterm deliveries between 32° to 34⁶ weeks of gestation were compared, there were no differences between the incidence of PPH (0.9% vs. 0%) or hematocrit change pre- and postdelivery (4.2 ± 2.3 vs. 4.8 ± 2.9). Comparing late preterm deliveries between 35° and 36⁶ weeks of gestation, there was no significant difference in the incidence of PPH (13% vs. 11.4%) or the mean hematocrit change pre- and postdelivery (5.0 ± 3.0 vs. 5.1 ± 2.8). In term cesarean deliveries, the incidence of PPH was 2.2% in the retrospective ICC group and 1.4% in the prospective UCM group. There was no difference in mean hematocrit change pre- and postdelivery (5.9 ± 3.7 vs. 6.2 ± 2.8).

CONCLUSION

DCC or UCM was not associated with the increased risk for PPH or significant change in maternal hematocrit pre- and postdelivery in very preterm singleton, moderate preterm, very preterm twin gestation, late preterm deliveries and term cesarean sections.

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.

Effects of Umbilical Cord Milking on Term Infants Delivered by Cesarean Section

OBJECTIVE

Umbilical cord milking (UCM) is an efficient way to achieve optimal placental transfusion in term infants born by cesarean section (CS). However, it is not frequently performed due to concern for short-term adverse effects of increased blood volume, such as polycythemia and hyperbilirubinemia. The aim of this study is to evaluate the short-term effects of UCM on term infants delivered by CS.

STUDY DESIGN

We conducted a pre- and postimplementation cohort study comparing term infants delivered by CS who received UCM five times (141 infants, UCM group) during a 6-month period (August 1, 2017 to January 31, 2018) to those who received immediate cord clamping (ICC) during the same time period (105 infants, postimplementation ICC) and during a 3-month period (October1, 2016 to December 31, 2016) prior to the implementation of UCM (141 infants, preimplementation ICC).

RESULTS

Mothers were older in UCM group compared with both ICC groups. There were no significant differences in other maternal or neonatal characteristics. Although this study was not powered to detect differences in outcomes, the occurrence of hyperbilirubinemia needing phototherapy, symptomatic polycythemia, NICU admissions, or readmissions for phototherapy was similar between the groups.

CONCLUSION

UCM intervention was not associated with increased incidence of phototherapy or symptomatic polycythemia in term infants delivered by CS.

Placental transfusion and short-term outcomes among extremely preterm infants

OBJECTIVE

To compare short-term outcomes after placental transfusion (delayed cord clamping (DCC) or umbilical cord milking (UCM)) versus immediate cord clamping among extremely preterm infants.

DESIGN

Retrospective study.

SETTING

The Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network registry.

PATIENTS

Infants born <29 weeks' gestation in 2016 or 2017 without congenital anomalies who received active treatment after delivery.

INTERVENTION/EXPOSURE

DCC or UCM.

MAIN OUTCOME MEASURES

Primary outcomes: (1) composite of mortality or major morbidity by 36 weeks' postmenstrual age (PMA); (2) mortality by 36 weeks PMA and (3) composite of major morbidities by 36 weeks' PMA. Secondary composite outcomes: (1) any grade intraventricular haemorrhage or mortality by 36 weeks' PMA and (2) hypotension treatment in the first 24 postnatal hours or mortality in the first 12 postnatal hours. Outcomes were assessed using multivariable regression, adjusting for mortality risk factors identified a priori, significant confounders and centre as a random effect.

RESULTS

Among 3116 infants, 40% were exposed to placental transfusion, which was not associated with the primary composite outcome of mortality or major morbidity by 36 weeks' PMA (adjusted OR (aOR) 1.26, 95% CI 0.95 to 1.66). However, exposure was associated with decreased mortality by 36 weeks' PMA (aOR 0.71, 95% CI 0.55 to 0.92) and decreased hypotension treatment in first 24 postnatal hours (aOR 0.66, 95% CI 0.53 to 0.82).

CONCLUSION

In this extremely preterm infant cohort, exposure to placental transfusion was not associated with the composite outcome of mortality or major morbidity, though there was a reduction in mortality by 36 weeks' PMA.

TRIAL REGISTRATION NUMBER

NCT00063063.

Neonatal outcomes in preterm multiples receiving delayed cord clamping

OBJECTIVE

To compare neonatal outcomes in singletons versus multiples, first-born versus second-born multiples and monochorionic versus dichorionic/trichorionic multiples <33 weeks' gestational age (GA) who received delayed cord clamping (DCC).

DESIGN

Retrospective, observational study of 529 preterm infants receiving ≥30 s DCC. Generalised estimating equations and mixed effects models were used to compare outcomes in singletons versus multiples and monochorionic versus dichorionic/trichorionic multiples. Wilcoxon signed-rank and McNemar tests were used to compare first-born versus second-born multiples.

SETTING

Level III neonatal intensive care unit, California, USA.

PATIENTS

433 singletons and 96 multiples <33 weeks' GA, born January 2008-December 2017, who received DCC.

RESULTS

86% of multiples and 83% of singletons received DCC. Multiples had higher GA (31.0 weeks vs 30.6 weeks), more caesarean sections (91% vs 54%), fewer males (48% vs 62%) and higher 12-24 hour haematocrits (54.3 vs 50.5) than singletons. Haematocrit difference remained significant after adjusting for birth weight, delivery type and sex. Compared with first-born multiples, second-born multiples were smaller (1550 g vs 1438 g) and had lower survival without major morbidity (91% vs 77%). Survival without major morbidity was not significant after adjusting for birth weight. Compared with dichorionic/trichorionic multiples, monochorionic multiples had slightly lower admission temperatures (37.0°C vs 36.8°C), although this difference was not clinically significant. There were no other differences in delivery room, respiratory, haematological or neonatal outcomes between singletons and multiples or between multiples' subgroups.

CONCLUSIONS

Neonatal outcomes in preterm infants receiving DCC were comparable between singletons and multiples, first and second order multiples and monochorionic and dichorionic/trichorionic multiples.