Monitoring at Birth

Maintenance of Normal Body Temperature Immediately After Birth: Term and Late Preterm Newborns

Last Full Review: ILCOR 2022

Newborn infants are at a greater risk of heat loss immediately after birth due to their large surface area to body mass ratio, decreased subcutaneous fat and other characteristics. Body temperature may fall by 2° C to 4° C in the first 10 to 20 minutes after birth (Dahm and James 1972, 504). Hypothermia in newborns puts them at risk for several potentially life-threatening complications including hypoxia, metabolic acidosis, cardiovascular complications and hypoglycemia, and it is an independent predictor (Trevisanuto, Testoni, and de Alemeida 2018, 333) of neonatal mortality. While definitions for normothermia and hypothermia in the newly born may vary, it is agreed that the temperature of newly born infants should be maintained between 36.5° C and 37.5° C immediately after birth and through to hospital admission (Trevisanuto, Testoni, and de Alemeida 2018, 333). The World Health Organization recommends a “warm chain” of interlinked procedures at birth to minimize heat loss in all newborns, beginning with immediate drying using a warm towel or cloth and placing the newborn on the mother’s chest or abdomen (skin-to-skin contact) while drying the newborn (World Health Organization 1997). Other recommended interventions in the warm chain include placing a cap on the head and covering the newborn with a second towel. Is there evidence to support other interventions besides drying to maintain a normal temperature immediately after birth in late preterm and term infants?

 

Evidence Summary

A 2022 systematic review and Consensus on Science with Treatment Recommendations (Wyckoff et al. 2022, e483; de Almedia et al. 2022a) aimed to compare various methods to maintain normal temperature immediately after birth in late preterm and term infants with maintaining normal temperature by drying alone. Methods searched for included increased room temperature of 23° C or higher, thermal mattress, plastic bag or wrap, hat, heating and humidification of gases used for resuscitation, radiant warmer (with or without servo control), early monitoring of temperature, warm bags of fluid, warmed swaddling/clothing, skin-to-skin care with a parent, or any combination of these interventions. The evidence that was identified allowed for several comparisons. All randomized controlled trials (RCTs) included in the review had exclusion criteria for infants at high risk of needing resuscitation or who received resuscitation, and no studies included out-of-hospital births. No evidence from RCTs was found for heating and humidification of gases used for resuscitation, use of a radiant warmer, warm bags of fluid, or warmed swaddling/clothing compared with standard care or any other intervention (Wyckoff et al. 2022, e483; de Almedia et al. 2022a).

For increased room temperature compared with no increased room temperature, evidence from one cluster RCT (Duryea et al. 2016, 505) with 825 late preterm and term newborn infants was identified, all born by caesarean section in an operating room, comparing outcomes at a temperature of 23° C with 20° C. For infants born when room temperature was 23° C compared with 20° C, mean temperatures on admission were 0.3° C higher, which was considered to be clinically significant. More infants were normothermic with a room temperature of 23° C compared with 20° C (RR, 1.25; 95% CI, 1.11–1.42; 130 more infants per 1,000 [95% CI, 55 more to 209 more]), and fewer infants had moderate hypothermia (less than 36° C) (RR, 0.26; 95% CI, 0.16–0.42; 140 fewer infants per 1,000 [95% CI, 158 fewer to 109 fewer]) (Wyckoff et al. 2022, e483; de Almedia et al. 2022a).

For skin-to-skin care with a parent compared with no skin-to-skin care, the mean temperature on admission was 36.6° C (MD, 0.32° C higher with skin-to-skin care; 95% CI, 0.1° C higher to 0.54° C higher), and more infants were normothermic with skin-to-skin care (RR, 1.39; 95% CI, 0.91–2.12; 239 more infants per 1,000 [95% CI, 55 fewer to 688 more]). Fewer infants developed hypoglycemia with skin-to-skin care versus no skin-to-skin care (RR, 0.16; 95% CI, 0.05–0.53; 273 fewer infants per 1,000 [95% CI, 309 fewer to 153 fewer]), and fewer infants were admitted to the neonatal intensive care units (RR, 0.34; 95% CI, 0.14–0.83; 46 fewer infants per 1,000 [95% CI, 60 fewer to 12 fewer]) (Wyckoff et al. 2022, e483; de Almedia et al. 2022a).

For using a plastic bag or wrap compared with no plastic bag or wrap, studies were included where infants had been dried or not dried before use of the plastic bag or wrap. The mean temperature on admission was 36.3° C (MD, 0.29° C higher with use of a plastic bag; 95% CI, 0.2° C higher to 0.37° C higher). Meta-analysis of data showed that fewer infants died (i.e., greater survival to hospital discharge) when a plastic bag or wrap was used (RR, 0.95; 95% CI, 0.60–1.51; 49 fewer infants per 1,000 died with use of a plastic bag/wrap [95% CI, 392 fewer to 500 more]), and more infants were normothermic on admission (RR, 1.50; 95% CI, 1.20–1.89; 203 more infants per 1,000 [81 more to 3,629 more were normothermic]) (Wyckoff et al. 2022, e483; de Almedia et al. 2022a).

For plastic bag or wrap use combined with skin-to-sin care compared with skin-to-skin care alone, the mean body temperature was 36° C (MD, 0.2° C higher when a plastic bag or wrap was added to skin-to-skin care [95% CI, 0.1° C higher to 0.3° C higher]). More infants were normothermic on admission with the combined intervention (RR, 1.39; 95% CI, 1.08–1.79; 86 more infants per 1,000 more were normothermic when a plastic bag/wrap was added to skin-to-skin care [95% CI, 18 more to 174 more per 1000]), and fewer infants were admitted to a neonatal intensive care unit or special care unit (RR, 0.26; 95% CI, 0.03–2.26; 21 fewer infants per 1,000 [95% CI, 28 fewer to 36 more per 1,000]) (Wyckoff et al. 2022, e483; de Almedia et al. 2022a).

Several comparisons had limited and very low-certainty evidence, and/or lacked statistical and/or clinical significance for outcomes, and are not reported here, including:

• Thermal mattresses versus no thermal mattress.
• Plastic bag or wrap versus drying compared with plastic bag or wrap without drying.
• Plastic bag or wrap without drying compared with a thermal nest.
• Early versus later skin-to-skin care.
• Continuously active warming blankets plus skin-to-skin care compared with standard care.
• Skin-to-skin care compared with a plastic bag or wrap.

 

The International Liaison Committee on Resuscitation (ILCOR) treatment recommendations stemming from this complex review for late preterm and term newborn infants (34 week’s gestation or more) suggest the use of room temperatures of 23° C compared with 20° C 20° C at birth to maintain normothermia, and for infants at low risk of needing resuscitation, the use of skin-to-skin care with a parent immediately after birth. If skin-to-skin care is not possible, it is reasonable to consider the use of a plastic bag or wrap, among other measures, to maintain normal temperature (Wyckoff et al. 2022, e483; de Almedia et al. 2022a).

Insights and Implications

The complex systematic review by ILCOR identified evidence to support three interventions without evidence of adverse effects. This review has been used to inform the Red Cross guidelines, with additional considerations. Not all delivery and operating rooms have the capability to alter room temperatures, and not all deliveries occur in a delivery or operating room. Additional research is needed to determine if the use of plastic bags or wraps may cause harm and to evaluate alternative methods for maintaining normothermia such as use of a thermal mattress or other conductive heat sources (pre-warmed clothing and hats, etc.).

Maintenance of Normal Body Temperature Immediately After Birth: Preterm Newborns

Last Full Review: ILCOR 2022

Hypothermia in the initial hours after birth is an issue that is associated with higher mortality and morbidity in newborns (Trevisanuto et al. 2018, 333; Perlman et al. 2015, S204; Sprecher et al. 2021, 270). A previous International Liaison Committee on Resuscitation (ILCOR) systematic review (Ramaswamy et al. 2022, 81) evaluated strategies to maintain normothermia in the delivery room and improve survival in late preterm and term neonates (34 or more week’s gestation) and concluded that a room temperature of 23° C and skin-to-skin contact soon after birth may prevent hypothermia in this population. The current ILCOR systematic review (Ramaswamy et al. 2023, 109934) and Consensus on Science with Treatment Recommendations (CoSTR) (Dawson et al. 2023; Berg et al. 2023) focuses on infants born at less than 34 week’s gestation.

 

Evidence Summary

A 2022 ILCOR systematic review (Ramaswamy et al. 2023, 109934) and CoSTR (Dawson et al. 2023; Berg et al. 2023) evaluated delivery room strategies to maintain normothermia and improve survival in preterm infants (born at less than 34 week’s gestation). Strategies included:

• Increased delivery room temperature 23.0° C or higher
• Thermal mattress
• Plastic bag or wrap
• Hat
• Heating and humidification of gases used for resuscitation
• Radiant warmer (with or without servo control)
• Early monitoring of temperature
• Warm bags of fluid
• Swaddling, skin-to-skin care
• Or combinations of these interventions

 

Interventions of interest were compared with drying alone, drying combined with the use of a plastic bag or wrap, or comparisons between interventions. Because strategies to maintain normothermia in preterm infants that have been studied typically involve a bundle of interventions rather than a single intervention, the review also focused on several clustered interventions and comparators. Use of a wrap or bag was a component of these clustered interventions. Primary outcomes included survival to hospital discharge and rate of normothermia on admission to a neonatal unit or postnatal ward. Secondary outcomes included body temperature and rates of moderate hypothermia, cold stress and hyperthermia, response to resuscitation and major morbidities.

A total of 18 randomized controlled trials (RCTs) and seven observational studies were included in data extraction used in the CoSTR. Multiple pairs of interventions were developed from the included data, while five comparisons were considered to provide adequate data for analysis and the development of treatment recommendations. The reader is encouraged to review the full and comprehensive CoSTR (Dawson et al. 2023; Berg et al. 2023) available online at (https://costr.ilcor.org/document/maintaining-normal-temperature-immediately-after-birth-in-preterm-infants-nls-5101-tf-sr) for detailed results from included studies. Results of interventions with significant findings or conclusions that led to treatment recommendations are recapped with this evidence summary.

Increased Room Temperature

For increased room temperature of 23.0° or higher compared with lower room temperature, two RCTs and three observational studies were included in the CoSTR (Dawson et al. 2023; Berg et al. 2023). Meta-analysis was not possible due to the low number of preterm infants included and variation in study design, including range of temperatures in the intervention and control groups. The limited evidence suggests that a temperature of 23.0° C  or higher in the delivery room or operating room increases body temperature on admission and reduces rates of moderate hypothermia. One observational study reported the association between ambient temperatures of 34° C to 28° C and higher admission temperatures and increased risk of hyperthermia (Johannsen et al. 2017, 235). The CoSTR authors note that a previous systematic review (Ramaswamy et al. 2022, 81) evaluating methods for maintaining normal temperature immediately after birth in term and late preterm infants led to recommendations for the use of a delivery room temperature of 23.0°C or higher, and that it is reasonable to suggest temperatures of 23.0°C or higher for all infants (Dawson et al. 2023; Berg et al. 2023).

Thermal Mattress

For thermal mattress compared with no thermal mattress, four RCTs were included in the CoSTR, with meta-analyses for comparison of thermal mattress versus no thermal mattress, and thermal mattress versus the use of a plastic bag or wrap. The evidence suggests a higher mean body temperature on admission and small improvement in the number of normothermic newborns with the use of a thermal mattress plus plastic bag or wrap compared with plastic bag or wrap alone, but possible harm in the form of an increased risk of hyperthermia in the thermal mattress plus plastic bag or wrap group (RR 0.46, 95% CI, 0.22–0.69) (Ramaswamy et al. 2023, 109934; Dawson et al. 2023; Berg et al. 2023).

Plastic Bag or Wrap

For a plastic bag or wrap compared with no use of a plastic bag or wrap, data from 11 RCTs shows a probable benefit for the outcome of survival to hospital discharge (RR 1.05; 95% CI, 1.00–1.10; ARD, 41 more infants survived per 1,000 [95% CI, 0 fewer to 82 more infants per 1000 survived; number needed to treat to benefit [NNTB], 24 infants]) (Ramaswamy et al. 2023, 109934). For the primary outcome of normothermia on admission, data from five RCTs showed there was a possible clinical benefit from the use of a plastic bag or wrap (RR 2.86; 95% CI, 1.66– 4.91; ARD, 238 more infants per 1,000 were normothermic; 95% CI, 85 more to 501 more infants per 1000 were normothermic; NNTB, 4 infants). Analysis of data for secondary outcomes suggest a possible benefit from the use of a plastic bag or wrap, with higher mean body temperature on admission, and fewer infants with hypothermia less than 36.5° C and fewer infants with moderate hypothermia. On subgroup analysis by gestational age, a significantly lower relative risk of moderate hypothermia was shown with use of a plastic bag or wrap for infants under 28 week’s gestation than in infants 28 to 33+6 week’s gestation. However, for meta-analysis of data from 12 RCTs of preterm infants born at less than 34 week’s gestation, moderate certainty evidence showed possible harm with increased risk of hyperthermia (greater than 38.0° C) (RR 3.67, 95% CI, 1.77–7.61) (Ramaswamy et al. 2023, 109934).

Head Covering

For a head covering (cap or bonnet) compared with no head covering, a single RCT (Trevisanuto et al. 2010, 914) was included in the CoSTR comparing a plastic cap (similar to a shower cap) with a plastic bag (no cap but head dried) or with no plastic cap or bag. All infants were dried and placed on prewarmed towels. Use of a prewarmed radiant warmer and other interventions were similar in both groups. A possible clinical benefit was seen with the use of a plastic cap compared with no plastic cap with more infants normothermic. For both mean body temperature and hypothermia less than 36.5° C, a probable clinical benefit was described. No harm or undesirable effects from use of a plastic cap were identified in this RCT (Dawson et al. 2023; Berg et al. 2023).

Heating and Humidification of Gases Used for Resuscitation

For heating and humidification of gases used for resuscitation compared with no heating and humidification, data from two RCTs could not show a clinical benefit or harm for the primary outcomes of survival to hospital discharge and normothermia on admission. For secondary outcomes of mean body temperature on admission and any hypothermia less than 36.5° C, two RCTs (McGrory et al. 2018, 47; Meyer et al. 2015, 245) with 476 participants provided evidence for a probable clinical benefit, with decreased risk of moderate hypothermia and intraventricular hemorrhage greater than Grade 2 (RR 0.39, 95% CI, 0.17–0.91; ARD, 50 fewer infants had intraventricular hemorrhage greater than grade 2 per 1000; 95% CI, 68 fewer to 7 fewer infants per 1000; NNTB 42 infants) (Dawson et al. 2023; Berg et al. 2023).

Radiant Warmer

For a radiant warmer (with or without servo control) compared with no radiant warmer, no studies were identified. A single RCT compared a servo-controlled radiant warmer to a radiant warmer in manual mode for preterm infants in the delivery room (Cavallin et al. 2021, 572). Evidence of probable clinical harm was found with decreased mean body temperature on admission (MD, 0.20° C; 95% CI, 0.07° C lower–0.33° C lower), increased risk of hypothermia less than 36.5° C (RR, 1.20; 95% CI, 1.01–1.42) and mild hypothermia (RR, 1.48; 95% CI, 1.09–2.01) with use of a servo controlled radiant warmer (Dawson et al. 2023; Berg et al. 2023).

Skin-to-Skin Care

For skin-to-skin care compared with no skin-to-skin care, evidence from two small RCTs was found to be insufficient to form a treatment recommendation. It was noted in the CoSTR that there is good evidence for the benefits of skin-to-skin contact for maintaining normal temperature immediately after birth in late preterm and term infants (Ramaswamy et al. 2022, 81) and for maintaining subsequent normal temperature when used soon after birth for low and very-low birth weight infants in low- and middle-income countries. This indirect evidence was used to generate a good practice statement for use of skin-to-skin contact for preterm infants (Dawson et al. 2023; Berg et al. 2023).

The systematic review concludes that a delivery room temperature of 23.0° C or higher, radiant warmer in manual mode, use of a plastic bag or wrap and a head covering is suggested for preterm newborn infants born at less than 34 week’s gestation, while heated humidified gas and thermal mattresses could be considered in addition to plastic bag or wrap provided resources allow, and in setting where hypothermic incidence is high. In addition, careful monitoring to avoid hyperthermia is needed (Ramaswamy 2023 et al, 109934).

The ILCOR treatment recommendations stemming from the CoSTR include (Dawson et al. 2023; Berg et al. 2023):

• A weak recommendation in preterm infants (born at less than 34 week’s gestation), as for late preterm and term infants (34 or more week’s gestation), suggests the use of room temperatures of 23.0° C or higher compared with 20° C at birth to maintain normal temperature.
• A conditional recommendation is made for preterm infants (born at less than 34 week’s gestation) immediately after birth, where hypothermia on admission is identified as a problem, it is reasonable to consider the addition of a thermal mattress, but there is a risk of hyperthermia.
• A strong recommendation is made in preterm infants (born at less than 34 week’s gestation) immediately after birth for the use of a plastic bag or wrap to maintain normal temperature. A good practice statement states that temperature should be carefully monitored and managed to prevent hyperthermia.
• A strong recommendation is made for preterm infants (born at less than 34 week’s gestation) immediately after birth to use a head covering to maintain normal temperature. A conditional recommendation states that it is reasonable to consider the use of a plastic cap, unless another form of head covering is used.
• A conditional recommendation for preterm infants (born at less than 34 week’s gestation) immediately after birth suggests the use of heated and humidified gases for respiratory support in the delivery room, where audit shows that admission hypothermia is a problem and resources allow.
• A good practice statement states that skin-to-skin care may be helpful for maintaining normal temperature where few other effective measures are available.

 

Insights and Implications

The Red Cross guidelines are informed by the ILCOR systematic review (Ramaswamy 2023 et al, 109934) and CoSTR (Dawson et al. 2023; Berg et al. 2023). While evidence supports a recommendation for a room temperature of 23.0° C or higher for preterm newborns (born at less than 34 week’s gestation) immediately after birth to maintain normal body temperature, it is important to keep in mind that a safe upper limit of room temperature has not been identified, and there is some evidence of an increased risk of hyperthermia with high (i.e., 34° C) ambient room temperatures, such as in tropical climates.

There is evidence that both hypothermia and hyperthermia in newborns is associated with adverse outcomes (de Almeida et al. 2014, 271; Wilson et al. 2016, 61). Some interventions also have some low or very-low certainty evidence for risk of hyperthermia, including the use of a thermal mattress and the use of a plastic bag or wrap. Although evidence is lacking, the risk may be higher when multiple interventions are used concurrently. A 2015 ILCOR systematic review (Perlman et al. 2015, S204) provided a recommendation suggesting that hyperthermia higher than 38.0° C be avoided in newborn preterm infants (born at less than 32 week’s gestation) due to the potential risks. The current review does not include this recommendation, but it has been included with the Red Cross guidelines as a good practice statement.

While several strategies to maintain normothermia were shown to be useful, the authors of the CoSTR acknowledge that a combination of several different interventions, such as a bundle of care or staged introduction of different measures, is likely to be needed for most preterm infants. There was insufficient evidence for any specific bundle to include in the CoSTR (Dawson et al. 2023; Berg et al. 2023).

Other systematic reviews have examined strategies for prevention of hypothermia after birth in very and extremely preterm neonates (Abiramalatha et al. 2021, e210775; McCall et al. 2005, Cd004210; Lin et al. 2015, 182). In the network meta-analysis by Abiramalatha (Abiramalatha et al. 2021, e210775) of randomized and quasi-randomized trials in infants born at less than 32 week’s gestation, the highest certainty evidence available was for use of a plastic bag or wrap, similar to the finding in the current ILCOR systematic review. Some evidence was also identified to support certain bundles of care, such as concurrent use of a plastic cap or heated and humidified gas, for maintaining normal body temperature and for reduced risk of brain injury or death. This indirect evidence supports the Red Cross good practice statement for consideration of using a combination of approaches for maintaining a normal temperature in preterm infants (born at less than 34 week’s gestation) immediately after birth.

Respiratory Function Monitoring During Neonatal Resuscitation at Birth

Last Full Review: ILCOR 2022

Respiratory function monitors are devices that continuously measure and display ventilatory parameters, such as respiratory rate, airway pressures, tidal volume, peak inspiratory pressure, mask leak and end-tidal carbon dioxide during ventilation. Respiratory function monitors are commonly used in a neonatal intensive care unit but have the potential for monitoring the effectiveness of ventilation for newborns in the delivery room who require respiratory support. A respiratory function monitor could help neonatal resuscitation teams avoid excessive tidal volume delivery that can lead to lung injury as well as inadequate tidal volumes resulting from mask leak, airway obstruction or insufficient ventilation pressures. Respiratory function monitor use in newborn resuscitation in the delivery room has been the subject of several recent trials.

 

Evidence Summary

A 2022 International Liaison Committee on Resuscitation (ILCOR) systematic review and Consensus on Science with Treatment Recommendations (CoSTR) (Wyckoff et al. 2022, e483; Fuerch et al. 2022) aimed to compare the use of a respiratory function monitor device with no respiratory function monitor in the delivery room for newborn infants receiving respiratory support at birth. This systematic review was an update of a 2015 ILCOR review (Perlman et al. 2015, S204) on the same topic that identified one eligible study and that led to weak recommendations suggesting against the routine use of flow and volume monitoring as well as capnography for babies who receive positive pressure ventilation at birth.

The 2022 review (Fuerch et al. 2022) identified three randomized controlled trials (RCTs) (Zeballos et al. 2019, 1368; van Zanten et al. 2021, 317; Schmölzer et al. 2012, 377) involving 443 newborns. Meta-analyses of data from the RCTs could not exclude clinical benefit or harm from displaying a respiratory function monitor compared with not displaying a respiratory function monitor for outcomes of intubation in the delivery room, achieving desired tidal volumes in the delivery room, pneumothorax, death before hospital discharge, severe intraventricular hemorrhage (grades 3 or 4) and bronchopulmonary dysplasia/chronic lung disease (Fuerch et al. 2022). A possible clinical benefit was suggested with displaying a respiratory function monitor for the outcome of intraventricular hemorrhage (all grades). The CoSTR authors noted that it is uncertain if the difference in intraventricular hemorrhage between groups in the two RCTs was attributable to the respiratory function monitor or a chance finding (Wyckoff et al. 2022, e483; Fuerch et al. 2022).

The ILCOR review concluded that there is insufficient evidence to make a recommendation for or against the use of a respiratory function monitor in newborn infants receiving respiratory support at birth (Wyckoff et al. 2022, e483; Fuerch et al. 2022).

Insights and Implications

The systematic review found a lack of clinical benefit with respiratory function monitor use in newborns receiving respiratory support with the possible exception of all grades of intraventricular hemorrhage. Many research questions remain, including cost effectiveness, training requirements, and the ability of respiratory function monitoring during resuscitation to change the proportion of time spent delivering a target tidal volume.

Methods to Assess Heart Rate in Newborns

Last Full Review: ILCOR 2023

A newborn’s heart rate is considered the prime indicator of their overall status, pointing to the effectiveness of spontaneous breathing and/or the need for supportive interventions. A rising heart rate indicates effective respiratory and resuscitative efforts, and thus, it is critical to be able to assess the newborn’s heart rate accurately and quickly after delivery. A previous International Liaison Committee on Resuscitation (ILCOR) Consensus on Science with Treatment Recommendations (CoSTR) (Perlman et al. 2015, S204; Wyckoff et al. 2020, S185) suggested the use of an electrocardiogram (ECG) for heart rate assessment of a newborn infant requiring resuscitation in the delivery room, and auscultation with pulse oximetry where ECG is not available. Several new studies of modalities and devices for estimating heart rate in newborns were noted on an evidence update in 2020, and in 2022 a systematic review (Wyckoff et al. 2022, e483) by ILCOR looked for evidence of improved clinical outcomes with use of ECG compared with pulse oximetry. For 2023, ILCOR conducted a systematic review to assess the diagnostic characteristics of various devices and methods for assessment of heart rate immediately after birth.

 

Evidence Summary

A 2023 ILCOR systematic review and CoSTR (Kawakami et al. 2023; Berg et al. 2023) evaluated evidence for the use of auscultation, palpation, pulse oximetry, doppler device, digital stethoscope and other newer modalities compared with an ECG and in-between intervention comparisons for the assessment of heart rate in newborns. The primary outcomes of interest were time-to-first heart rate assessment from the device placement, time-to-first heart rate assessment from birth and accuracy of heart rate assessment. Evidence included in the review was used for seven different comparisons. An abbreviated summary of findings is presented here, and the reader is referred to the full CoSTR at https://costr.ilcor.org/document/heart-rate-assessment-methods-in-delivery-room-diagnostic-characteristics-nls-5200-tf-sr.

Pulse Oximeter Compared with an ECG

For the comparison of a pulse oximeter with an ECG, data from pooled observational studies found the time-to-first heart rate assessment from the device (pulse oximetry) placement was slower than ECG in presenting a heart rate signal (pooled difference heart rate from pulse oximeter, 57 seconds slower; 95% CI, 13 seconds slower to 101 seconds slower, P<0.05) (Kawakami et al. 2023; Berg et al. 2023). Evidence was graded low certainty with data from six observational studies including 323 infants. Limited data from randomized controlled trials (RCTs) (136 infants) showed no significant difference between a pulse oximeter and an ECG for time-to-first heart rate assessment from the device placement. Using pooled data from observational studies, a pulse oximeter was slower than an ECG for the outcome of time-to-first heart rate assessment from birth (pooled difference in heart rate from pulse oximeter, 52 seconds slower; 95% CI, 9 seconds slower to 94 seconds slower, P<0.05) (Kawakami et al. 2023; Berg et al. 2023). A significant difference in time for first heart rate assessment from birth was not seen between a pulse oximeter and an ECG using limited data from RCTs (Kawakami et al. 2023; Berg et al. 2023).

For accuracy of heart rate assessment, meta-analysis showed that a pulse oximeter may be accurate, but imprecise, for heart rate estimation at birth. The average difference in the measured heart rate using a pulse oximeter and an ECG was small, but with a very wide 95% CI, indicating that a pulse oximeter may at times underestimate or overestimate the heart rate. The sensitivity of a pulse oximeter for identification of neonatal bradycardia (less than 100 beats per minute on an ECG) was 0.83 (95% CI, 0.76–0.88) and specificity was 0.97 (95% CI, 0.93–0.94). The CoSTR concludes for this comparison that pulse oximeter is slower and imprecise for newborn heart rate assessment in the delivery room compared with ECG, and may show lower heart rates compared with an ECG for the first 2 minutes to 6 minutes after birth (Kawakami et al. 2023; Berg et al. 2023).

Auscultation Compared with an ECG

For the comparison of auscultation with an ECG, pooled data from observational studies did not show a significant difference between auscultation and ECG for time-to-first heart rate assessment from the device placement. However, time-for-first heart rate assessment from birth was faster with auscultation than for an ECG at birth (Kawakami et al. 2023; Berg et al. 2023). The CoSTR authors commended that this was considered likely to be due to the time required for placement of the ECG leads and turning on the ECG monitor. Auscultation was also found to be accurate, but imprecise, at 90 seconds and 120 seconds after birth when compared with ECG (Kawakami et al. 2023; Berg et al. 2023).

Palpation Compared with an ECG

For the comparison of palpation with an ECG, only one study with limited data was included. Palpation was found to be inaccurate and imprecise at 60 seconds, 90 seconds, 120 seconds and 300 seconds after birth (Kawakami et al. 2023; Berg et al. 2023).

Palpation Compared with Auscultation

For the comparison of palpation with auscultation, one study reported that palpation of the femoral pulse, brachial pulse and umbilical cord pulse all showed very poor agreement with the auscultated heart rate (Kawakami et al. 2023; Berg et al. 2023).

Digital Stethoscope Compared with an ECG

For the comparison of a digital stethoscope with an ECG, one study reported the digital stethoscope was accurate for heart rate assessment but imprecise, including during crying periods (Kawakami et al. 2023; Berg et al. 2023).

Doppler Ultrasound Compared with an ECG

For the comparison of doppler ultrasound with an ECG, limited data from a single study with very-low certainty evidence reported that doppler ultrasound was faster for presenting a heart rate signal than an ECG. Doppler ultrasound was accurate and precise for heart rate assessment compared with an ECG in two observational studies with very-low certainty evidence downgraded for risk of bias, imprecision and applicability concern (Kawakami et al. 2023; Berg et al. 2023).

Dry Electrodes Incorporated Into a Belt Compared with an ECG

For the comparison of dry electrodes incorporated into a belt with an ECG, a single observational study reported dry electrodes incorporated into a belt to be faster for presenting a heart rate signal compared with an ECG (Kawakami et al. 2023; Berg et al. 2023). A second study reported dry electrodes incorporated into a belt to be faster than an ECG for presenting a heart rate signal from birth. Dry electrodes incorporated into a belt, when considered as an index text, was accurate and precise for heart rate estimation compared with an ECG in 22 observational studies with very-low certainty evidence (Kawakami et al. 2023; Berg et al. 2023).

The ILCOR treatment recommendations from the CoSTR (Kawakami et al. 2023; Berg et al. 2023) include a conditional recommendation that suggests that the use of an ECG for heart rate assessment of a newborn infant immediately after birth is reasonable when accurate heart rate estimation is needed after birth and resources permit. A second conditional recommendation suggests that pulse oximetry and auscultation may be reasonable alternatives for heart rate assessment, but the limitations of these modalities should be kept in mind. A good practice statement was made to use auscultation with or without pulse oximetry to confirm the heart rate when electrocardiography is unavailable, not functioning or when pulseless electrical activity is suspected. There was insufficient evidence to make a treatment recommendation regarding the use of digital stethoscopes, audible or visible Doppler ultrasound, dry electrode technology or any other newer modalities for heart rate assessment of a newborn in the delivery room (Kawakami et al. 2023; Berg et al. 2023).

Insights and Implications

The Red Cross guidelines are informed by the 2023 ILCOR CoSTR (Kawakami et al. 2023; Berg et al. 2023). The available evidence suggests that an ECG is more rapid and accurate for the assessment of heart rate in newborns in the delivery room when compared with a pulse oximeter and other newer methods of assessment of heart rate in newborns.

While auscultation appeared accurate and faster than an ECG for time-to-first heart rate assessment from birth, it was noted to be imprecise. Data for pulse oximeters suggests they may be slower than an ECG for time-to-first heart rate assessment from birth and may be accurate, but imprecise, for heart rate estimation at birth. Some studies noted heart rate values significantly lower with pulse oximeter for the first 2 minutes to 6 minutes after birth than heart rate by an ECG. Auscultation and pulse oximetry or both are commonly used for heart rate assessment in newborns and are reasonable alternatives to an ECG when they are not available. In the first few minutes after birth, these approaches to estimating heart rate may be accurate but more imprecise than an ECG, especially in bradycardic newborns and those requiring resuscitation.

The Red Cross guidelines from 2022 have been updated to reflect both the 2023 systematic review of the diagnostic characteristics of various devices and methods for assessment of heart rate immediately after birth and the 2022 ILCOR systematic review of clinical outcomes of different methods of heart rate assessment.