Mild Neonatal Acidemia is Associated with Neonatal Morbidity at Term

An Assessment of the Relationships Between Umbilical Cord Blood Gas Analysis, APGAR (Appearance, Pulse, Grimace, Activity, and Respiration) Scores, and Neonatal Outcomes

Introduction Intrapartum hypoxic-ischemic injury is a condition that significantly affects neonatal health and, therefore, needs to be attended to urgently. Umbilical cord blood gas analysis (BGA) results and APGAR (appearance, pulse, grimace, activity, and respiration) scores are commonly used to assess birth asphyxia and the severity of neonatal acidemia. In this context, this study was conducted to investigate the correlations of BGA results and APGAR scores with neonatal outcomes to determine the combined value of BGA results and APGAR scores in neonatal health assessment. Methods The sample of this retrospective cohort study consisted of 593 consecutive-term newborns delivered in a tertiary referral center in Turkey between January 2020 and December 2022. All newborns' maternal, delivery, and neonatal characteristics, BGA results, and APGAR scores were analyzed to determine correlations with composite adverse neonatal outcomes. The study's primary outcome was defined as the rate of the composite adverse neonatal outcomes, whereas the secondary outcomes were determined as the impact of maternal and neonatal characteristics on composite neonatal morbidity and the correlation between the one- and five-minute APGAR scores and umbilical cord BGA parameters. Results Of the 593 infants included in the study, 191 (32.2%) infants experienced composite adverse neonatal outcomes, primarily mechanical ventilation (47.7%), followed by respiratory distress/syndrome (35.6%). Significant correlations were detected between composite adverse neonatal outcomes and advanced maternal age (p = 0.025), cesarean section history (p < 0.001), preterm delivery (p < 0.001), lower one- and five-minute APGAR scores (p < 0.001 for both cases), and acidemia severity (p = 0.007). However, the correlations between BGA parameters and APGAR scores were weak (r < 0.2). Conclusion This study investigated the correlations between neonatal mortality and morbidity and maternal factors, delivery characteristics, and fetal features, including one- and five-minute APGAR scores and BGA parameters. Nevertheless, weak correlations between BGA parameters and APGAR scores warrant further comprehensive prospective studies.

Umbilical Artery Cord Gas Abnormalities in the Presence of a Nuchal Cord in Term Singleton Pregnancies: A Cohort Study

OBJECTIVE

The clinical significance of nuchal cord (NC) at the time of delivery is unclear. Studies have found that NC is associated with lower umbilical artery (UA) pH. Since fetal hypercarbia precedes respiratory acidosis, we hypothesize UA pCO2 is elevated in neonates with NC at the time of delivery.

STUDY DESIGN

This is a secondary analysis of a prospective cohort study of women with full-term singleton pregnancies admitted in labor or for induction of labor at an institution with a universal umbilical cord gas policy. We compared patients with NC at the time of delivery to those without NC. Women were excluded if they did not have validated UA gases, had a major fetal anomaly, or had an intrauterine fetal demise. The primary outcome of the study was UA pCO2. Secondary outcomes were other components of UA gas and neonatal morbidity composite. Baseline characteristics were compared utilizing chi-square or Fisher's exact test or the Student's t-test. UA gas parameters were compared using the Kruskal-Wallis test. Multivariable logistic regression was utilized to adjust for confounders.

RESULTS

Of the 8,580 study participants, 7,608 had validated umbilical cord gases. The incidence of NC in the population was 24.15% (n = 1,837). UA pCO2 was higher in those with NC than without (58 mm Hg [53-64] vs. 55 mm Hg [50-60], p < 0.01). There was a greater odds of hypercarbia in the NC group (pCO2 > 65 mmHg; adjusted odds ratio [aOR]: 1.97, 95% confidence interval [CI]: 1.72-2.25, p < 0.01). Additionally, the NC group was more likely to be mildly acidemic (pH < 7.2, aOR: 1.74, 95% CI: 1.51-2.01, p < 0.01). There was no difference in composite neonatal morbidity between the groups.

CONCLUSION

NC is associated with an increased risk of hypercarbia and acidemia. However, this is not associated with increased risk of neonatal morbidity.

KEY POINTS

· Nuchal cord is associated with an increased risk of hypercarbia and mild acidemia.. · Nuchal cord is not likely associated with neonatal morbidity.. · Neonatal management should not be altered due to the presence of a nuchal cord at delivery..

The Risk of Neonatal Morbidity in Umbilical Artery Hypercarbia and Respiratory Acidosis

OBJECTIVE

To test the hypothesis that elevated umbilical artery (UA) partial pressure of carbon dioxide (pCO2) is associated with neonatal morbidity and to compare the risk of neonatal morbidity with different patterns of UA acidosis.

STUDY DESIGN

This was a secondary analysis of a prospective cohort of term, singleton, nonanomalous deliveries with universal cord gas collection. The primary outcome was composite neonatal morbidity. Multivariable logistic regression was used to determine the relative risk (RR) for neonatal morbidity in patients with and without UA hypercarbia. A receiver operating characteristic curve determined the predictive value of pCO2 for neonatal morbidity. An additional multivariable logistic regression was used to evaluate the risk of neonatal morbidity in different patterns of UA acidosis.

RESULTS

UA hypercarbia was associated with an increased risk of neonatal morbidity (RR: 2.56, 95% confidence interval [CI]: [2.07, 3.17]). After adjusting for UA acidemia, this association remained significant (adjusted RR: 1.39, 95% CI: [1.05, 1.83]). UA pCO2 was less predictive of neonatal morbidity than UA pH (area under the curve [AUC]: 0.65, 95% CI: [0.62, 0.68] vs. AUC: 0.72, 95% CI: [0.69, 0.75], p < 0.01). The odds ratios for neonatal morbidity for respiratory, mixed, and metabolic acidosis compared with normal cord gases were 1.48 (95% CI: [0.88, 2.49]), 6.41 (95% CI: [3.68, 11.17]), and 7.49 (95% CI: [5.76, 9.72]), respectively, p-trend < 0.01.

CONCLUSION

UA hypercarbia is an independent predictor of neonatal morbidity, even in the setting of concomitant UA acidemia. UA mixed and metabolic acidosis carry significantly greater risk of neonatal morbidity compared with respiratory acidosis.

KEY POINTS

· UA pCO2 is associated with neonatal morbidity.. · UA respiratory acidosis is the UA cord gas pattern least associated with neonatal morbidity.. · UA pH is a superior predictor of neonatal morbidity compared with UA pCO2..

Association between Elevated Intrauterine Resting Tone during Labor and Neonatal Morbidity

OBJECTIVE

Internal contraction monitoring provides a quantitative assessment of intrauterine resting tone. During the course of labor, elevated intrauterine resting tone may be identified. We hypothesized that elevated intrauterine resting tone could lead to compression of the spiral arteries, thus limiting uterine blood flow and resulting in neonatal compromise. Therefore, our objective was to assess the association between elevated resting tone during labor and neonatal morbidity.

STUDY DESIGN

This was a secondary analysis of a prospective cohort study of singleton deliveries at ≥37 weeks of gestation. Patients with ruptured membranes and an intrauterine pressure catheter in place for at least 30 minutes prior to delivery were included. Intrauterine resting tone was calculated as the average baseline pressure between contractions during the 30 minutes prior to delivery. The study group had elevated intrauterine resting tone, defined as intrauterine resting tone ≥75th percentile (≥12.3 mm Hg). Primary outcome was composite neonatal morbidity: hypoxic-ischemic encephalopathy, hypothermia treatment, intubation, seizures, umbilical arterial pH ≤7.1, oxygen requirement, or death. Secondary outcomes included umbilical artery pH <7.2, lactate ≥4 mmol/L, and rates of neonatal intensive care unit admission.

RESULTS

Of the 8,580 patients in the cohort, 2,210 (25.8%) met the inclusion criteria. The median intrauterine resting tone was 9.7 mm Hg (interquartile range: 7.3-12.3 mm Hg). Elevated resting tone was associated with a shorter median duration of the first stage of labor (10.0 vs. 11.0 hours, p < 0.01) and lower rates of labor induction and oxytocin augmentation (p < 0.01). Neonatal composite morbidity was higher among patients with elevated intrauterine resting tone (5.1 vs. 2.9%, p = 0.01). After adjusting for chorioamnionitis and amnioinfusion, elevated intrauterine resting tone was associated with increased risk of neonatal morbidity (adjusted odds ratio: 1.70, 95% confidence interval: 1.06-2.74).

CONCLUSION

Our findings suggest that elevated intrauterine resting tone is associated with increased risk of neonatal composite morbidity.

KEY POINTS

· Higher intrauterine resting tone is associated with increased risk of neonatal morbidity.. · Elevated intrauterine tone can negatively impact umbilical artery pH and lactate levels.. · If elevated intrauterine pressure is noted, we recommend close monitoring of fetal status..

Spinal Hypotension and Time from Spinal-to-Delivery in Scheduled Cesarean Deliveries: Association with Neonatal Acidosis

OBJECTIVE

This work aimed to study the effect of sustained hypotension after spinal on neonatal acidosis and adverse outcomes in those undergoing scheduled cesarean delivery (CD) with universal prophylactic vasopressor exposure and to examine differences in spinal-to-delivery time by neonatal acidosis status.

STUDY DESIGN

 This retrospective cohort study conducted at a quaternary care center from January 2019 to December 2021 included singleton, term, nonanomalous pregnancies, with scheduled CD under spinal anesthesia. Hypotension was defined as a systolic blood pressure (SYS-BP) < 100 mm Hg (SYS-BP100) or a >20% drop from baseline blood pressure (SYS-BP20). Both the occurrence of hypotension and its magnitude and duration were studied; the latter through the development of a hypotension index. The 90th and 95th percentiles of the hypotension index for SYS-BP20 and SYS-BP100, respectively, were used to define sustained hypotension. The primary outcome was neonatal acidosis (umbilical artery pH ≤ 7.1 or base excess ≤ -12 mmol). Secondary outcomes were composites of neonatal (CNAO) and maternal (CMAO) adverse outcomes. Multivariable Poisson regression models with robust error variance analysis was used to estimate adjusted relative risks (aRRs) and 95% confidence intervals (CIs).

RESULTS

 Our study included 332 individuals who underwent scheduled CD; among them 330 (99.4%) received prophylactic vasopressors. The rate of neonatal acidosis was 4.2%. Sustained hypotension after spinal anesthesia, which occurred in 12.3% of the cohort, was associated with increased risk for neonatal acidosis (aRR 3.96, 95% CI 1.21-12.98), but was not associated with CNAO or CMAO. Time from spinal-to-delivery was not different in those with and without neonatal acidosis.

CONCLUSION

 Despite universal exposure to prophylactic vasopressors, sustained hypotension after spinal anesthesia was still associated with neonatal acidosis, but no other adverse perinatal outcomes. Our findings may provide additional support for the adoption of prophylactic vasopressors to reduce spinal hypotension and downstream effects on the neonate from intraoperative hemodynamic instability.

KEY POINTS

· Despite prophylactic vasopressors during scheduled CD, neonatal acidosis occurred in 4% of subjects.. · Sustained hypotension after spinal anesthesia was associated with neonatal acidosis, but not adverse neonatal outcomes.. · Spinal-to-delivery time was not associated with neonatal acidosis in scheduled CD..

Intrapartum electronic fetal monitoring features associated with a clinical diagnosis of nonreassuring fetal status

BACKGROUND

Nonreassuring fetal status detected by continuous electronic fetal monitoring accounts for almost 1 in 4 primary cesarean deliveries. However, given the subjective nature of the diagnosis, there is a need to identify the electronic fetal monitoring patterns that are clinically considered nonreassuring.

OBJECTIVE

This study aimed to describe which electronic fetal monitoring features are most commonly associated with first-stage cesarean delivery for nonreassuring fetal status, and to evaluate the risk of neonatal acidemia following cesarean delivery for nonreassuring fetal status.

STUDY DESIGN

This was a nested case-control study in a prospectively collected cohort of patients with singleton pregnancies at ≥37 weeks' gestation, admitted in spontaneous labor or for induction of labor from 2010 to 2014 at a single tertiary care center. Patients with preterm pregnancies, multiple gestations, planned cesarean delivery, or nonreassuring fetal status in the second stage of labor were excluded. Cases were identified as having nonreassuring fetal status on the basis of what was documented in the operative note by the delivering physician. Controls were patients without nonreassuring fetal status within 1 hour of delivery. Cases were matched to controls in a 1:2 ratio by parity, obesity, and history of cesarean delivery. Electronic fetal monitoring data were abstracted by credentialed obstetrical research nurses for the 60 minutes before delivery. The primary exposure of interest was the incidence of high-risk category II electronic fetal monitoring features in the 60 minutes before delivery; in particular, the incidence of minimal variability, recurrent late decelerations, recurrent variable decelerations, tachycardia, and >1 prolonged deceleration were compared between groups. We also compared neonatal outcomes between cases and controls, including fetal acidemia (umbilical artery pH <7.1), other umbilical artery gas analytes, and neonatal and maternal outcomes.

RESULTS

Of the 8580 patients in the parent study, 714 (8.3%) underwent cesarean delivery for nonreassuring fetal status in the first stage of labor. Patients diagnosed with nonreassuring fetal status requiring cesarean delivery were more likely to have recurrent late decelerations, >1 prolonged deceleration, and recurrent variable decelerations compared with controls. More than 1 prolonged deceleration was associated with 6 times increased rate of nonreassuring fetal status diagnosis resulting in cesarean delivery (adjusted odds ratio, 6.73 [95% confidence interval, 2.47-8.33]). Rates of fetal tachycardia were similar between groups. Minimal variability was less common in the nonreassuring fetal status group compared with controls (adjusted odds ratio, 0.36 [95% confidence interval, 0.25-0.54]). Compared with control deliveries, cesarean delivery for nonreassuring fetal status was associated with nearly 7 times higher risk of neonatal acidemia (7.2% vs 1.1%; adjusted odds ratio, 6.93 [95% confidence interval, 3.83-12.54]). Composite neonatal morbidity and composite maternal morbidity were more likely among patients delivered for nonreassuring fetal status in the first stage (3.9% vs 1.1%; adjusted odds ratio, 5.70 [2.60-12.49]; and 13.3% vs 8.0%; adjusted odds ratio, 1.99 [1.41-2.80]).

CONCLUSION

Although multiple category II electronic fetal monitoring features have been traditionally linked to acidemia, the presence of recurrent late decelerations, recurrent variable decelerations, and prolonged decelerations seemed to concern obstetricians enough to surgically intervene for nonreassuring fetal status. A clinical intrapartum diagnosis of nonreassuring fetal status in the setting of these electronic fetal monitoring features is also associated with increased risk of acidemia, suggesting clinical validity to the diagnosis of nonreassuring fetal status.

Comparison between the modified French AmbUlatory Cesarean Section and standard cesarean technique-a randomized double-blind controlled trial

BACKGROUND

The French AmbUlatory Cesarean Section is a cesarean delivery technique, which includes a vertical fascial incision to the left of the linea alba and an extraperitoneal approach to the uterus. The presumed benefits of this technique are decreased postoperative pain and accelerated recovery. However, evidence supporting these impressions is scarce.

OBJECTIVE

This study aimed to compare maternal recovery after French AmbUlatory Cesarean Section vs standard cesarean delivery technique.

STUDY DESIGN

In this double-blind randomized controlled trial, women undergoing elective cesarean delivery at term were allocated into French AmbUlatory Cesarean Section vs standard cesarean delivery technique. A modified French AmbUlatory Cesarean Section technique was used, adhering to all French AmbUlatory Cesarean Section operative steps except for the extraperitoneal approach. In both groups, the use of intravenous hydration, intrathecal morphine, and bladder catheter was avoided, and all women were encouraged to stand and walk 3 to 4 hours after the operation. The primary adverse composite outcome included either of the following: a visual analog scale score of >6 at 3 to 4 hours after the operation, an inability to stand up and walk to the restroom 3 to 4 hours after the operation, and a 15-Item Quality of Recovery (QoR) questionnaire score of <90 at 24 hours after the operation. The women were followed up for 6 weeks.

RESULTS

Overall, 116 women were included in the trial (58 in each group). The adverse composite outcome did not differ between the 2 groups (38.9% for the French AmbUlatory Cesarean Section group vs 53.8% for the regular cesarean delivery group; P=.172). In both groups, more than 90% of the women were able to get up and walk 3 to 4 hours after the operation. Compared with the standard cesarean delivery group, the French AmbUlatory Cesarean Section group had a longer duration of the operation (43.7±11.2 vs 54.4±11.3 minutes; P<.001), a higher rate of intraoperative complications (0.0% vs 13.8%; P=.006), and a higher rate of umbilical cord pH level of <7.2 (3.4% vs 17.2%; P=.029) were noted. Evaluation via phone call 1 week after the operation showed better quality of recovery scores in the French AmbUlatory Cesarean Section group than in the standard cesarean delivery group (27.1±8.4 vs 24.6±8.0; P=.043). Other secondary outcomes did not differ between the 2 groups.

CONCLUSION

As excellent maternal recovery was noted in both groups, we believe that the main factor affecting this recovery is the perioperative management (including avoidance of the use of intraoperative intravenous hydration, intrathecal morphine, and bladder catheter, with early postoperative mobilization). The maternal and neonatal safety outcomes of the French AmbUlatory Cesarean Section technique remain to be proven by larger-scale high-quality randomized controlled trials.

Multi-organ dysfunction in infants with acidosis at birth in the absence of moderate to severe hypoxic ischemic encephalopathy

INTRODUCTION

Infants with perinatal asphyxia are at risk for organ failure aside from the brain, regardless of the severity of the asphyxial insult. We aimed to evaluate the presence of organ dysfunction other than the brain in newborns with moderate to severe acidosis at birth, in the absence of moderate to severe hypoxic ischemic encephalopathy.

MATERIALS AND METHODS

Data of 2 years were retrospectively recorded. Late preterm and term infants admitted to the intensive care unit with ph < 7.10 and BE < -12 mmol/l in the first hour were included in the absence of moderate to severe hypoxic ischemic encephalopathy. Respiratory dysfunction, hepatic dysfunction, renal dysfunction, myocardial depression, gastrointestinal problems, hematologic system dysfunction, and circulatory failure were evaluated.

RESULTS

Sixty-five infants were included [39 (37-40) weeks, 3040 (2655-3380) grams]. Fifty-six (86 %) infants had one or more dysfunction in any system [respiratory: 76.9 %, hepatic: 20.0 %, coagulation: 18.5 %, renal: 9.2 %, hematologic: 7.7 %, gastrointestinal: 3.0 %, and cardiac: 3.0 %]. Twenty infants had at least two affected systems. The incidence of coagulation dysfunctions was higher in the infants with severe acidosis (n = 25, ph < 7.00) than the infants with moderate acidosis (n = 40: pH = 7.00-7.10); 32 % vs 10 %; p = 0.03.

CONCLUSIONS

Moderate to severe fetal acidosis is associated with the development of extra-cranial organ dysfunctions in infants who do not require therapeutic hypothermia. A monitoring protocol is needed for infants with mild asphyxia in order to identify and manage potential complications. Coagulation system should be carefully evaluated.

Is acidemia at birth a risk factor for functional gastrointestinal disorders?

Functional gastrointestinal disorders (FGIDs) are common in early childhood. It has been demonstrated that neonatal acidemia at delivery can lead to significant neonatal morbidity. The primary aim of this study was to evaluate the relationship between acidemia at birth and the development of FGIDs, as regurgitation, colic, and constipation, in term infants. Term newborns born at the Foggia University Hospital, Italy during the year 2020 were included in the study. As per routine clinical practice, a cord blood gas analysis on a blood sample drawn from the umbilical artery (UA) of each infant immediately after birth was performed, and Apgar score was recorded. One year after birth, each infant's parents were interviewed through a phone call to investigate development of FGIDs, feeding practices, and morbidities. During the study period, 1574 term newborns met the inclusion criteria. The prevalence of infantile colic, regurgitation, and constipation was higher in infants with low UA pH (colic 51.5% vs. 25.4%, p < 0.001; regurgitation 30.6% vs. 15.2%, p < 0.001; constipation 24.6% vs. 16.0%, p = 0.015), with infants having moderate-severe acidemia facing the highest risk for all the examined FGIDs. In binary logistic regression analyses, UA pH and perinatal antibiotic exposure proved to be independently associated with the later diagnosis of each FGID.

CONCLUSION

Newborns with acidemia at birth appear to face a higher risk of FGIDs in infancy. Avoiding low cord blood pH should continue to be the goal for obstetricians, while enhanced long-term surveillance for infants who experienced birth acidemia should be required.

WHAT IS KNOWN

• Cord blood gas analysis is recommended in all high-risk deliveries, and in some centers, it is performed after all deliveries. • Neonatal acidemia at birth has been linked to adverse outcomes, mainly neurological. Recently, perinatal asphyxia has been reported to increase the risk of developing necrotizing enterocolitis in term infants.

WHAT IS NEW

• An association between acidemia at birth and risk of developing FGIDs such as regurgitation and colic during the first year of life had never been described so far. • An increased surveillance of infants with low UA pH at birth may be beneficial and could allow for early detection of any of the reported FGIDs.

Concentration of Serum Biomarkers of Brain Injury in Neonates With a Low Cord pH With or Without Mild Hypoxic-Ischemic Encephalopathy

Objective

To determine the concentrations of four neuroprotein biomarkers and 68 miRNAs in neonates with low cord pH and/or mild hypoxic-ischemic encephalopathy (HIE).

Study Design

A prospective cohort study enrolled neonates with low cord pH (n = 18), moderate-severe HIE (n = 40), and healthy controls (n = 38). Groups provided serum samples at 0–6 h of life. The concentrations of biomarkers and miRNAs were compared between cohorts.

Result

The low cord pH and moderate-severe HIE groups had increased concentrations of GFAP, NFL and Tau compared to controls (P < 0.05, P < 0.001, respectively). NFL concentrations in mild HIE was higher than controls (P < 0.05) but less than moderate-severe HIE (P < 0.001). Of 68 miRNAs, 36 in low cord pH group and 40 in moderate-severe HIE were upregulated compared to controls (P < 0.05). Five miRNAs in low cord pH group (P < 0.05) and 3 in moderate-severe HIE were downregulated compared to controls (P < 0.05).

Conclusion

A biomarker panel in neonates with low cord pH may help clinicians make real-time decisions.

The association of fetal acidemia with adverse neonatal outcomes at time of scheduled cesarean delivery

BACKGROUND

Fetal acidemia at the time of a scheduled cesarean delivery is generally unexpected. In the setting of reassuring preoperative monitoring, the duration of fetal acidemia in this scenario is presumably brief. The neonatal sequelae and risks associated with brief fetal acidemia in this setting are unknown.

OBJECTIVE

We aimed to assess whether fetal acidemia at the time of a scheduled prelabor cesarean delivery is associated with adverse neonatal outcomes.

STUDY DESIGN

This was a retrospective cohort study of singleton, term, nonanomalous, liveborn neonates delivered by scheduled cesarean delivery that was performed under regional anesthesia from 2004 to 2014 at a single tertiary care center with a universal umbilical cord gas policy. Neonates born to laboring gravidas and those whose cesarean delivery was performed for nonreassuring fetal status were excluded. All included patients had reassuring preoperative fetal monitoring. The primary outcome was a composite adverse neonatal outcome that included neonatal death, encephalopathy, therapeutic hypothermia, seizures, intubation, and respiratory distress. This outcome was compared between patients with and those without fetal acidemia (umbilical artery pH <7.2). A multivariable logistic regression was used to adjust for confounders. Cases of fetal acidemia were further characterized as respiratory, metabolic, or mixed acidemia based on additional umbilical cord gas values. Secondary analyses examining the association between the type of acidemia and neonatal outcomes were also performed.

RESULTS

Of 2081 neonates delivered via scheduled cesarean delivery, 252 (12.1%) had fetal acidemia at the time of delivery. Acidemia was more common in breech neonates and in neonates born to gravidas with obesity and gestational diabetes mellitus. Compared with fetuses with normal umbilical artery pH, those with fetal acidemia were at a significantly increased risk for adverse neonatal outcome (adjusted relative risk, 2.95; 95% confidence interval, 2.03-4.12). This increased risk was similar regardless of the type of acidemia.

CONCLUSION

Even a brief period of mild acidemia is associated with adverse neonatal outcomes at the time of a scheduled cesarean delivery despite reassuring preoperative monitoring. Addressing modifiable intraoperative factors that may contribute to fetal acidemia at the time of a scheduled cesarean delivery, such as maternal hypotension and prolonged operative time, is an important priority to potentially decrease neonatal morbidity in full-term gestations.