DOI: https://doi.org/10.21203/rs.3.rs-1644314/v1
Background: Premature babies often have long hospital stays and frequent blood tests; they often develop anemia requiring multiple blood transfusions. Placental transfusion via delayed cord clamping (DCC) or umbilical cord milking (UCM) helps increase blood volume. We hypothesized umbilical cord milking (UCM), together with DCC, would be a superior in reducing blood transfusions.
Objectives: To compare the effects of DCC and DCC combined with UCM on hematologic outcomes among preterm infants.
Methods: 120 singleton preterm infants born at 280/7- 336/7 weeks of gestation at Thammasat University Hospital were enrolled in a randomized controlled, open label, trial. They were placed into three groups (1:1:1) by a block-of-three randomization: DCC for 45 seconds, DCC with UCM performed before clamping (DCM-B), and DCC with UCM performed after clamping (DCM-A). The primary outcomes were hematocrit levels and number of infants receiving blood transfusions during the first 28 days of life. Intraventricular hemorrhage (IVH) and necrotizing enterocolitis (NEC) were secondary outcomes. Analysis were performed with an intent-to-treat approach.
Results: 120 preterm infants were randomized. There was no statistically significant difference in neonatal outcomes; hematocrit on admission 54.0 ± 5.5, 53.3 ± 6.0, and 54.3 ± 5.8, receiving blood transfusions 25%, 20% and 12.5%, incidence of NEC 7.5, 0 and 10% in the DCC, DCM-B and DCM-A groups, respectively. There were no preterm infants with severe IVH, polycythemia, maternal or neonatal death.
Conclusion: Although it was not significantly different, preterm infants in DCM-B and DCM-A groups requiring blood transfusion were less than those in DCC group. All three placental transfusion techniques provided the same benefit in preterm infants in reducing the incidence of severe IVH and NEC without increasing complication and comorbidity.
Trial Registration: TCTR20190131002
Registered 31 January 2019 - Retrospectively registered
http://www.thaiclinicaltrials.org/show/TCTR20190131002
At present, premature babies have a higher survival rate; however, the problem of anemia persists. This is mainly caused by iatrogenic blood loss resulting in clinical symptoms such as tachycardia, apnea, and slow growth. Some preterm infants need blood transfusions, but this increases the risk of developing transfusion-related acute lung injury and necrotizing enterocolitis (NEC). Many studies have shown there are numerous benefits to preterm infants receiving placental transfusion, including less necessary blood transfusion and lower incidence of severe intraventricular hemorrhage (IVH) and NEC1-3.
Currently, performing delayed cord clamping (DCC) is the standard care practice recommended for preterm infants by many professional organizations4-6. The American College of Obstetricians and Gynecologists recommend DCC 30-60 seconds for preterm deliveries4. For the infants’ position, infants who were placed on the maternal abdomen or chest received the same amount of blood from DCC as holding the infants at the level of the vagina7,8.
There were concerns that performing DCC may delay neonatal resuscitation, therefore umbilical cord milking (UCM) is an alternative placental transfusion technique. In preterm infants, UCM has the same benefits as DCC in terms of red blood cell (RBC) transfusion requirements9,10. A meta-analysis suggests that DCC or UCM both have advantages over immediate cord clamping regarding decreased blood transfusion incidence, decreased overall mortality, and lower risk of intraventricular hemorrhage11. Currently, UCM should not be performed in extremely preterm infants due to UCM significantly increasing the incidence of severe IVH more than DCC12-14.
In a study of premature infants born by cesarean section, the DCC group had a blood volume greater than the early cord clamping group. However, it was not significantly different, and this may be because the umbilical arteries still have blood flow from the baby to the placenta: umbilical vein blood flow is bidirectional. When or if the baby cries, blood from the baby flows back to the placenta15. Hence, we hypothesized that preterm infants who underwent DCC combined with UCM, before or after umbilical cord clamping, may receive more blood volume than those who had DCC alone, which may result in a reduced number of infants needing RBC transfusions during the first 28 days of life.
Premature infants born at GA 280/7- 33 6/7 weeks at Thammasat University Hospital, Pathumthani, Thailand, between July 1st, 2016, and December 31st, 2018 were enrolled in a randomized controlled trial by the delivery nurse team. We excluded infants who were multiples, diagnosed with severe disabilities, having chromosomal abnormalities, hydrops fetalis, intrauterine growth retardation, or from mothers with placenta previa with hemorrhage, abruption placenta, prolapsed cord, or having fetal distress before birth as well as those mothers who were giving birth before or on arrival or unable to give consent. This study was approved by the Human Research Ethics Committee No.1, Faculty of Medicine,Thammasat University. The informed consent was obtained before delivery by our research staff.
Randomization
Participants were divided into three groups (1:1:1) by a block-of-three randomization using sealed envelopes, performed by a research team. Envelopes were opened by the delivery nurse team, when mothers commenced preterm labor and entered the active phase, meaning regular uterine contractions at least four times in 20 minutes with cervix dilatation > 4 cm or when mothers had premature birth scheduled due to severe preeclampsia for either cesarean opearation or vaginal birth.
Placental transfusion techniques
DCC means delaying cutting the umbilical cord after birth for 45 seconds. DCM-B is DCC for 45 seconds with an obstetrician then performing UCM on about 25 cm length of the cord three times, next cutting the umbilical cord. DCM-A is DCC for 45 seconds with the umbilical cord cut to around 25 cm length; after this, the pediatrician milks the umbilical cord toward the infant three times, and the cord is next cut to standard. Digital clocks were used to time the procedure.
During these interventions, infants born by cesarean section were placed on their maternal abdomen, and those born by vaginal delivery, the obstetrician held the baby at the level of the maternal vaginal level.
After cutting the cord, the preterm infants were wrapped in a plastic bag and placed on a warm mattress in the radiant warmer. Neonatal resuscitation was decided by the attending physician at birth.
All infants received our standard care, which includes a starter iron supplement of 4 mg/kg/day after they can tolerate 120 ml/kg/day of milk for two days, an ultrasound brain screening within 14 and 28 days of life by a pediatric radiologist who was blinded to the intervention, jaundice assessment using serum microbilirubin, verification of hematocrit levels within one hour of birth and checked weekly until discharge. If they are discharged home before 28 days of life, there was an appointment to follow up and check hematocrit levels at the 4th week of age.
Outcomes
All outcomes were analyzed by blinded team researchers who did not know the code of the intervention. The primary outcomes were that premature infants received RBC transfusions within 28 days of age and had hematocrit levels checked on admission, at 1st and 4th week of age. Our pediatric team maintained the authority to determine if transfusions were required based on our guideline. Neonatal outcomes such as IVH (using grading system proposed by Papile et al.16), NEC, respiratory distress syndrome (RDS), patent ductus arteriosus (PDA), bronchopulmonary dysplasia (BPD) defined as oxygen requirement at 28 days of age, retinopathy of prematurity (ROP), and length of hospital stay (LOS) were determined. The morbidities including neonatal polycythemia, hyperbilirubinemia, neonatal death, maternal postpartum hemorrhage and death were collected.
Sample sizes
Katheria AC, et al.6 had 52% of the preterm infants in their DCC group receive blood transfusions. We, therefore, estimated 20% of infants in the DCM-A and DCM-B groups would require blood transfusions. Using 80% power and a confidence value of 0.05 with two-way calculation, 40 preterm infants were required for each group.
Statistical analysis
Demographic data was reported using percentage (%), mean, and SD median. ANOVA test was used to compare continuous variables that were normally distributed; Kruskall-Wallis was used for continuous variables not normally distributed. Pearson chi-square and Fisher’s exact test compared categorical outcome variables. p <0.05 is considered significant. Data analyses were performed using an intent-to-treat basis.
Of the 192 preterm infants born during the study, 72 were excluded due to multiple pregnancy (n = 24), diagnosis with severe disabilities (n = 3), chromosomal abnormalities (n = 1), hydrops fetalis (n = 1), intrauterine growth retardation (n = 8), mother with placenta previa with hemorrhage or abruption placenta (n = 3), prolapsed cord (n = 2), fetal distress before birth (n = 7), birth before or on arrival (n = 15), and absence of consent (n = 8) (Fig. 1). Finally, 120 were enrolled, with 40 infants randomized into each group.
Baseline characteristics were not different between groups, with the notable exception of GA, Apgar scores at 1 and 5 min (Table 1). Eight infants (two in the DCC group, five in DCM-B, and one in DCM-A) did not receive placental transfusion; they required neonatal resuscitation and were analyzed in their assigned groups.
| Outcomes | DCC (n = 40) | DCM-B (n = 40) | DCM-A (n = 40) | p |
|---|---|---|---|---|
| Maternal age, y (mean ± SD) | 29.5 ± 6.0 | 28.3 ± 6.2 | 29.2 ± 7.7 | 0.24 |
| Complete prenatal steroid | 21 (52.5) | 14(35) | 19(47.5) | 0.95 |
| Cesarean section | 24(60) | 17(42.5) | 17(42.5) | 1.0 |
| Male | 21(52.5) | 20(50) | 21(52.5) | 1.00 |
| Gestational age, wk (mean ± SD) | 31.5 ± 1.7 | 32.1 ± 1.7 | 32.4 ± 1.1 | 0.01 |
| GA ≤ 32 week | 29 (72.5) | 23 (57.5) | 24(60) | 0.79 |
| Birth weight, g (mean ± SD) | 1724.3 ± 413.2 | 1785.3 ± 397.2 | 1880.6 ± 355.9 | 0.64 |
| Apgar at 1 min (median) | 9 (1–9) | 9 (4–9) | 9 (5–9) | < 0.01 |
| Apgar at 5 min (median) | 10 (3–10) | 10 (5–10) | 10 (7–10) | < 0.01 |
| Apgar < 7 at 1 min | 7(17.5) | 5(12.5) | 2(5) | < 0.01 |
| Apgar < 7 at 5 min | 2 (5) | 1 (2.5) | 0(0) | 0.04 |
There were no significant differences in requiring positive pressure ventilation after birth, temperature on admission, incidence of hypothermia (temperature < 36.5oC); no infants had polycythemia. No mothers experienced postpartum hemorrhage or death (Table 2).
| Outcomes | DCC (n = 40) | DCM-B (n = 40) | DCM-A (n = 40) | p |
|---|---|---|---|---|
| Delivery room temperature (°C) (mean ± SD) | 25.1 ± 0.8 | 24.9 ± 0.9 | 25 ± 0.6 | 0.1 |
| Temperature on admission (°C) (mean ± SD) | 36.9 ± 0.6 | 36.7 ± 0.7 | 36.7 ± 0.6 | 0.44 |
| Temperature < 36.5oC | 8 (20) | 13 (32.5) | 9 (22.5) | 0.77 |
| Required positive pressure ventilation | 8 (20) | 7 (17.5) | 4 (10) | 0.18 |
| Intubation in delivery room | 6 (15) | 4 (10) | 2 (5) | 0.52 |
Hematologic outcomes are shown in Table 3. Hematocrit concentrations were similar on admission, at the age of 1 week, and 4 weeks. We had 25, 20 and 12.5% of infants who received RBC transfusion in the DCC, DCM-B and DCM-A groups, respectively (p = 0.24).
| Outcomes | DCC | DCM-B | DCM-A | p |
|---|---|---|---|---|
| Hct* on admission, % (mean ± SD) | 54.0 ± 5.5 | 53.3 ± 6.0 | 54.3 ± 5.8 | 0.88 |
| 1st week Hct, % (mean ± SD) | 46.0 ± 6.2 | 46.1 ± 6.9 | 46.6 ± 7.4 | 0.53 |
| 4th week Hct, % (mean ± SD) | 33.8 ± 4.9 | 33.2 ± 5.9 | 33.5 ± 5.4 | 0.56 |
| Blood loss within 28 days (ml) | 19.5 ± 9.2 | 18.7 ± 10.2 | 14.9 ± 8.5 | 0.52 |
| Need for red blood cell transfusion within 28 days | 10 (25) | 8 (20) | 5 (12.5) | 0.24 |
| * Hct, Hematocrit. | ||||
No differences were observed in the incidence of RDS, PDA, NEC, and peak bilirubin levels between groups. For the DCC group, 97.5% received phototherapy, which was significantly more than the DCM-B (92.5%) and DCM-A (87.5%) (p < 0.01); none of these needed total exchange transfusions. The BPD incidence, days for ventilation and oxygen use, as well as LOS were significantly higher in the DCC group. The incidence of IVH grade I in DCC group (30%) was not significantly different from DCM-B (15%) and DCM-A groups (32.5%), (p = 0.22). No infant was diagnosed with ROP, severe IVH or died (Table 4).
| Outcomes | DCC | DCM-B | DCM-A | p |
|---|---|---|---|---|
| Peak bilirubin level, mg/dL (mean ± SD) | 9.5 ± 2.7 | 9.5 ± 2.4 | 9.7 ± 1.9 | 0.07 |
| Phototherapy | 39 (97.5) | 37 (92.5) | 35 (87.5) | < 0.01 |
| Duration of phototherapy, days (mean ± SD) | 6.2 ± 3.3 | 5.5 ± 4.5 | 4.8 ± 3.2 | 0.16 |
| Respiratory distress syndrome | 19 (47.5) | 12 (30) | 10 (25) | 0.67 |
| Surfactant | 12 (30) | 8 (20) | 5 (12.5) | 0.13 |
| Patent ductus arteriosus | 12 (30) | 8 (20) | 7 (17.5) | 0.48 |
| Bronchopulmonary dysplasia | 18 (45) | 11 (27.5) | 6 (15) | 0.01 |
| Ventilator, days (mean ± SD) | 3.6 ± 9.2 | 1.6 ± 3.7 | 0.5 ± 1.7 | < 0.01 |
| Oxygen therapy, days (mean ± SD) | 28.6 ± 30 | 16.1 ± 18.0 | 10.1 ± 14.6 | < 0.01 |
| Intraventricular hemorrhage Grade I | 12 (30) | 6 (15) | 13 (32.5) | 0.22 |
| Necrotizing enterocolitis | 3 (7.5) | 0 | 4 (10) | 0.78 |
| Length of hospital stay, days (mean ± SD) | 42.7 ± 29.2 | 31.7 ± 18.9 | 26 ± 15.3 | 0.01 |
During hospitalization, preterm infants have multiple blood tests, causing anemia which requires a blood transfusion. Recombinant erythropoietin may help, but it is prohibitively expensive. Rabe H, et al found that the combination of a 30-second delay in cord clamping with infant iron supplementation reduced the number of transfusions17. There is, however, a concern that DCC may delay neonatal resuscitation; hence, UCM may be a safer option.
Many studies have reported the same benefits for preterm infants whether they received DCC or UCM. Shirk SK, et al saw no statistically significant differences in occurrences of transfusion, NEC, and IVH between DCC and UCM in preterm infants who were GA 23–34 weeks 6 days18. Rabe H, et al compared milking the cord four times versus clamping the cord for 30 seconds after delivery: this also showed no significant differences in mean hemoglobin at 1 hour after birth, the number of infants needing transfusions, or the number of transfusions themselves10. Meta-analysis suggested performing UCM in preterm < 27 weeks’ gestation was cautioned against regarding increased risk of severe IVH14.
UCM combined with DCC; DCM-B or DCM-A should, theoretically, increase blood volume in preterm infants, compared to DCC alone. In our study, all three techniques showed no variations in hematocrit after intervention. Preterm infants in DCM-B (20%) and DCM-A (12.5%) groups requiring blood transfusion were fewer than those in DCC (25%) group but it was not significantly different. Our study had a lower rate of infants requiring transfusion compared to Jasani B et.al19, a systematic review and network meta-analysis, which showed the rate of infants needing RBC transfusion in DCC group (38.3%) compared to immediate cord clamping (ICC) group (46.9%), and UCM (32.3%) compared to ICC group (46.9%)19. There were two reasons: first, there was a difference in the GA of the infants enrolled in the study. Jasani B et.al19 enrolled more infants with a lower GA (GA 220/7- 36 6/7 weeks) than those in our study (GA 280/7- 33 6/7 weeks). Second, all our techniques, DCC (45 s), DCM-B and DCM-A, were different from Jasani B et.al19, ICC, DCC (30–120 s), UCM followed by DCC. Our practices may result in the infant receiving a greater amount of blood.
Placental transfusions also reduced the incidence and severity of IVH as well as NEC. Our study showed NEC incidence was 0–10%, averaging 5.8%, versus our previous report at 15%20 and no infants had severe IVH. Without any apparent variation in outcomes, all placenta transfusions had the same benefit. Of note, however, the DCC group had a significantly higher incidence of BPD, days of ventilation and oxygen use, and LOS as opposed to the other two groups. This was because infants in the DCC group had lower GA and had a higher incidence of RDS, PDA, and needed surfactant therapy more than those in DCM-B and DCM-A groups.
No observable negative effects occurred; most importantly, there were no cases of polycythemia, or neonatal death, and no maternal postpartum hemorrhage or death. Another benefit was that hypothermia incidence was reduced by half, compared to our prior intervention period. Shirk SK, et al reported performing DCC or UCM in low birthweight infants made the infants warmer than immediate cord clamping as placental transfusion gives warm blood17. As is generally known, hyperbilirubinemia is a concern for all preterm infants. Many studies1,9,18,21 as well as ours showed no differences in terms of bilirubin levels and duration of phototherapy.
Our study was novel in comparing DCM-B and DCM-A to DCC in a randomized controlled trial. However, our limitation was internal validity discrepancy. There was a statistically significant difference in baseline characteristics; GA and Apgar score. Therefore, sampling should be carried out using a stratified sampling method to achieve validity and the sample size requires a larger population to improve predictive power. Nonetheless, long-term follow up for neurodevelopmental outcomes should be future research.
All three methods of placental transfusion techniques, DCC, DCM-B and DCM-A, provided the same benefits for premature babies born at GA 28 and 336/7 weeks in terms of reducing the need for RBC transfusions, severities of IVH and incidence of NEC without increasing comorbidity.
DCC; Delayed cord clamping
UCM; Umbilical cord milking
DCM-B; DCC with UCM performed before clamping
DCM-A; DCC with UCM performed after clamping
IVH; Intraventricular hemorrhage
NEC; Necrotizing enterocolitis
RBC; Red blood cell
RDS; Respiratory distress syndrome
PDA; Patent ductus arteriosus
BPD; Bronchopulmonary dysplasia
ROP; Retinopathy of prematurity
LOS; Length of hospital stay
Ethics approval and consent to participate
The study was approved by the Human Research Ethics Committee No.1, Faculty of Medicine,Thammasat University, Thailand.
Participants’ informed consent was obtained from their parents.
Consent for publication: not applicable
As this manuscript does not contain any kind of content which can reveal patients’ identity, so, written informed consent for publication was not taken from their parents.
Availability of data and materials
The datasets generated during and/or analysed during the current study are not publicly available due technical limitations but are available from the corresponding author on reasonable request.
Competing interests
No financial or non-financial benefits have been received or will be received from any party related directly or indirectly to the subject of this article.
Funding: Thammasat University, Thailand
This funding source had no role in the design of this study and did not have any role during its execution, analyses, interpretation of the data, or decision to submit results.
Authors’ contribution
Dr. Prachukthum designed the study, analyzed the data and drafted the manuscript. Dr. Tanprasertkul analyzed the data and critically revised the manuscript. Dr. Somprasit assisted study design, interpreted the data, and critically revised the manuscript. All authors read and approved the final manuscript.
Acknowledgement
We appreciated Thammasat University for funding and admired nurses and pediatric and obstetric residents who helped our research.