Impact of Different Decision-to-Delivery Intervals on Maternal and Neonatal Outcomes in Women with a Positive Oxytocin Challenge Test: A Comparison of 75- versus 90-minute Thresholds

Introduction

The OCT is a crucial tool for assessing fetal well-being and placental functional reserve. By inducing uterine contractions and monitoring corresponding changes in fetal heart rate, OCT provides predictive value in identifying the risk of intrauterine hypoxia.¹ A positive OCT result is generally regarded as an indicator of fetal stress or potential hypoxia, during which the release of copeptin—a stress biomarker—tends to increase.^1,2 In clinical practice, such findings often necessitate timely intervention, including decisions regarding delivery.^3,4 A delay in intervention following a positive OCT may prolong fetal exposure to a stressed intrauterine environment. This sustained stress can increase the risk of fetal acidosis and hypoxia, which are established precursors to neonatal morbidity, including hypoxic-ischemic encephalopathy, respiratory distress, and need for neonatal intensive care. Therefore, determining the optimal timeframe for delivery—one that balances the urgency to relieve fetal stress against the need for adequate maternal preparation—is critical to minimizing adverse perinatal outcomes. However, there remains a lack of consensus on the optimal timing and management strategies for pregnant women with a positive OCT, particularly regarding whether immediate emergency cesarean delivery is required.^5,6 This uncertainty arises not only from difficulties in accurately judging the urgency of fetal risk but also from the need to balance the risks and benefits associated with different delivery options—such as discontinuing oxytocin and attempting vaginal delivery versus proceeding directly to surgery.^3,7 When emergency cesarean delivery is indicated, the Decision-to-Delivery Interval (DDI)—the time from the decision to perform a cesarean to the delivery of the fetus—serves as a key metric for evaluating the efficiency of obstetric emergency response. Existing studies suggest that while a prolonged DDI may increase potential risks, certain delays—especially under complex circumstances—do not necessarily lead to a significant rise in adverse maternal or neonatal outcomes.^5,8 For example, prolonging the interval after discontinuing oxytocin does not always correlate with increased neonatal morbidity.⁵

While evidence-based guidelines and extensive research exist for DDI in general emergency cesarean deliveries (eg, targeting ≤30 minutes for immediate threats to life or ≤75 minutes for urgent maternal or fetal indications), there is still a lack of evidence-based standards concerning the optimal DDI threshold specifically in the context of a positive OCT. An excessively short DDI might lead to increased maternal complications due to inadequate preoperative preparation, while an overly long DDI may worsen the adverse effects of fetal hypoxia exposure within the intrauterine environment.^3,4 We hypothesize that an overly short DDI may not improve maternal or neonatal outcomes and could potentially elevate the risk of complications. Therefore, this study aims to retrospectively analyze 191 cases of cesarean delivery following a positive OCT, focusing on comparing the impacts of two DDI thresholds—75 minutes and 90 minutes—on maternal and neonatal outcomes. Our goal is to provide an evidence-based reference to support rational decision-making regarding the timing of emergency cesarean delivery in the setting of a positive OCT, with the aim of reducing clinical disagreements and improving maternal and neonatal prognosis.

Patients and Methods

Study Design and Ethical Considerations

This was a retrospective observational study. The study protocol adhered to the principles of the Declaration of Helsinki (World Medical Association Inc., 2009) and was subject to ethical review and approval. Ethical approval was granted by the Ethics Committee of Guigang City People’s Hospital, in accordance with national regulations and the committee’s guidelines. Informed consent was waived owing to the retrospective nature of the study.

Data analysis will be conducted using coded information, ensuring that no personal details (such as contact information, addresses, etc) of the participants will be collected. All samples will be de-identified to fully protect the privacy rights of the participants. Furthermore, the data selected for this study will only be used for research purposes and will not be utilized for any other purposes. The public reporting of research results will not disclose any personal identities of the participants.

A total of 191 pregnant women who underwent cesarean delivery due to a positive OCT at Guigang City People’s Hospital between January 2020 and May 2025 were retrospectively enrolled. All procedures were performed under neuraxial anesthesia.

Oxytocin Challenge Test (OCT) Protocol

At our institution, the OCT was performed following a standardized protocol. For eligible women, intravenous oxytocin was administered via an infusion pump, starting at a low dose (typically 1–2 mU/min) and increased incrementally every 15–20 minutes until adequate uterine contractions (three contractions within 10 minutes) were achieved. Fetal heart rate (FHR) and uterine activity were continuously monitored using cardiotocography. A test was interpreted as positive if persistent late decelerations or significant variable decelerations were observed in association with at least 50% of the contractions, in the absence of maternal hypotension or hyperstimulation. The test was considered negative if no such decelerations occurred despite adequate contractions. All tests were interpreted by attending obstetricians.

Sample Size Consideration

As this was an exploratory, retrospective cohort study aiming to describe and compare outcomes based on existing clinical practice over a defined period, a formal a priori sample size calculation was not performed. Instead, we aimed to include all consecutive cases that met the inclusion criteria during the study period (January 2020 to May 2025) to maximize the available data and provide a comprehensive view of the clinical scenario. This approach is common in retrospective surgical timing studies where the population is defined by the availability of complete records over a specific timeframe. The final sample size of 191 reflects all eligible cases identified through our review.

Inclusion Criteria

• Singleton pregnancy with cephalic presentation.
• Gestational age ≥ 34 weeks.
• Positive OCT result.
• Cesarean delivery performed.
• Complete medical records available.

Exclusion Criteria

• Multiple gestation.
• Fetal congenital anomalies.
• Intrauterine fetal demise.
• Non-cephalic presentation (eg, breech or transverse lie).

Grouping Methods

The 191 cases were categorized according to the Decision-to-Delivery Interval (DDI) using two different threshold-based grouping strategies:

75-Minute Threshold (Based on the 2024 NICE Caesarean Birth Guideline)

The guideline recommends that category II cesarean deliveries should be completed within 75 minutes of the decision to operate.⁹ Accordingly, cases were divided into: DDI ≤75 minutes group (n=60), DDI >75 minutes group (n=131).

90-Minute Threshold (Sensitivity Analysis)

Given that only 23.13% of category I cesarean deliveries and 35.75% of category II deliveries achieve DDI ≤75 minutes in China,¹⁰ and considering that a DDI exceeding 90 minutes may surpass fetal compensatory capacity, potentially resulting in irreversible injury,^11,12 a further analysis using a 90-minute cutoff was performed. Cases were divided as: DDI ≤90 minutes group (n=85), DDI >90 minutes group (n=106).

Outcome Measures

To specifically analyze the impact of DDI, neonatal outcomes including asphyxia,¹³ meconium aspiration syndrome, and meconium-stained amniotic fluid¹⁴ were categorized as DDI-related, given their direct association with fetal distress and the urgency of delivery. Other adverse perinatal outcomes such as low Apgar scores and NICU admission, often linked with emergency cesarean and reflecting the urgency denoted by DDI, were also considered DDI-related.¹⁵ Remaining complications were classified as non-DDI-related.

Specifically, Among the Study Cohort

DDI-related complications (20 cases): neonatal asphyxia (n=2), meconium aspiration syndrome (n=2), meconium-stained amniotic fluid (n=16).

Non-DDI-Related Complications (36 Cases)

Preterm birth (n=6), neonatal hypoglycemia (n=4), maternal fever (n=2), prolonged premature rupture of membranes (n=4), maternal GBS colonization (n=11), neonatal caput succedaneum (n=1), maternal intrahepatic cholestasis (n=1), term low birth weight (n=2), neonatal cleft palate (n=1), neonatal pulmonary cystic adenomatoid malformation (n=1), and other complications (n=3).

It is important to note that this classification pertains only to cases where one or more of the specified complications occurred. The remaining 135 cases did not experience any of these complications during the study period and thus are not represented in either the DDI-related or non-DDI-related subgroup counts for complications.

The following measures were collected and compared between groups:

Baseline Characteristics: maternal age, gravidity, parity, BMI at delivery.

Surgical-Related Indicators: total operation time, skin incision-to-delivery interval, estimated intraoperative blood loss, pre- and postoperative white blood cell counts, neutrophil counts, hemoglobin levels.

Maternal and Neonatal Outcomes: postoperative hospital stay, postoperative fever, duration of postoperative antibiotics, neonatal birth weight, gestational age at delivery, neonatal asphyxia, neonatal intensive care unit (NICU) admission within 24 hours of birth, and hospitalization costs.

Statistical Analysis

Statistical analyses were performed using SPSS software (version 29.0). Continuous variables that followed a normal or approximately normal distribution are presented as mean ± standard deviation , and comparisons between groups were conducted using the independent samples t-test. Non-normally distributed continuous variables are expressed as median (interquartile range) and were compared using the Mann–Whitney U-test. Categorical variables are summarized as numbers and percentages (%), and group comparisons were made using the chi-square test or Fisher’s exact test when expected cell counts were less than 5. A two-tailed P-value of less than 0.05 was considered statistically significant.

Results

Comparison of Baseline Characteristics

There were no significant differences in maternal age, gravidity, parity, or BMI at delivery between the groups when stratified by the 75-minute threshold (P > 0.05). Similarly, when stratified by the 90-minute threshold, the baseline characteristics showed no statistically significant differences between the groups (P > 0.05) (Table 1).

Table 1 Comparison of Baseline Characteristics (n=191)

Comparison of Surgical and Laboratory-Related Parameters

In the comparison between the DDI ≤ 75 minutes group and the > 75 minutes group, postoperative white blood cell count [median 13.44 (IQR 11.19–15.50) vs 11.60 (10.03–13.42) ×10⁹/L, P < 0.001] and neutrophil count [median 10.72 (IQR 8.06–12.58) vs 8.99 (7.54–10.56) ×10⁹/L, P = 0.002] were significantly higher in the shorter DDI group. There were no statistically significant differences in other parameters such as operation duration and intraoperative blood loss (P > 0.05).

When comparing the DDI ≤ 90 minutes group with the > 90 minutes group, postoperative white blood cell count and neutrophil count showed no significant differences (P > 0.05). Other surgical-related indicators also did not differ significantly (Table 2).

Table 2 Comparison of Surgery-Related and Laboratory Indicators

Comparison of Maternal and Neonatal Outcomes

In the 75-minute threshold analysis, the DDI ≤ 75 minutes group exhibited a significantly higher rate of DDI-related neonatal NICU admission within 24 hours compared to the > 75 minutes group [20.00% (12/60) vs 6.11% (8/131), P < 0.05]. There were no statistically significant differences between the groups in neonatal birth weight, gestational age at delivery, neonatal asphyxia, postoperative hospital stay, duration of antibiotic use, hospitalization costs, or postoperative fever (P > 0.05).

In the 90-minute threshold analysis, the DDI ≤ 90 minutes group showed significantly higher rates of DDI-related NICU admission within 24 hours [14.47% (14/85) vs 5.66% (6/106), P < 0.05] and postoperative fever [11.76% (10/85) vs 0.94% (1/106), P = 0.003] compared to the > 90 minutes group. No statistically significant differences were observed between groups in neonatal birth weight, gestational age at delivery, neonatal asphyxia, postoperative hospital stay, duration of antibiotic use, or hospitalization costs (P > 0.05) (Table 3).

Table 3 Comparison of Maternal and Neonatal Outcomes

Discussion

Main Findings

This retrospective cohort study, which included 191 parturients with positive OCT who underwent cesarean delivery, revealed a key finding that challenges the conventional “the faster, the better” paradigm: excessively shortening the DDI may lead to unintended adverse maternal and neonatal outcomes. The results demonstrated that the group with a DDI ≤ 75 minutes exhibited a significantly higher maternal inflammatory response compared to the group with a DDI > 75 minutes, as indicated by increased white blood cell counts (median 13.44 vs 11.60 ×10⁹/L, P < 0.001) and neutrophil counts (median 10.72 vs 8.99 ×10⁹/L, P = 0.002). Concurrently, the proportion of neonates admitted to the NICU within 24 hours due to DDI-related reasons was significantly higher in the shorter DDI group (20.0% vs 6.1%, P < 0.05).

When extending the threshold to 90 minutes, maternal inflammatory markers tended to normalize; however, the rates of DDI-related NICU admissions (14.47% vs 5.66%, P < 0.05) and postoperative maternal fever (11.76% vs 0.94%, P = 0.003) remained significantly elevated in the shorter DDI group. It is noteworthy that traditional intraoperative indicators, such as operation time and estimated blood loss, showed no significant differences between the groups, suggesting that these adverse outcomes primarily stem from physiological changes induced by the compressed decision-making time rather than surgical technique. These findings may fundamentally question the traditional obstetric emergency paradigm that emphasizes extreme speed, instead highlighting the existence of a critical, optimized time window in the high-risk context of positive OCT. This window must balance the effective alleviation of fetal risk against the prevention of iatrogenic maternal and neonatal injury. Overall, aggressively shortening the DDI did not confer benefits in terms of major maternal or neonatal outcomes, which is consistent with previous studies.^5,8

Interpretation of Non-Significant Findings in Relation to Prior Evidence

It is equally important to interpret the lack of significant difference in several key maternal and neonatal outcomes between DDI groups. The finding that major outcomes—such as neonatal asphyxia, birth weight, gestational age, and core surgical metrics (eg, operative time, blood loss)—did not differ significantly at either the 75- or 90-minute threshold aligns with and corroborates a growing body of literature. Previous studies have suggested that moderately prolonging DDI does not inherently worsen perinatal outcomes in various emergency settings.^5,8,16–18 Our data extend this understanding to the specific context of a positive OCT. The absence of difference in these major outcomes suggests that, within the studied timeframes, the physiological urgency denoted by a positive OCT may not translate into a linear benefit from ever-shorter delivery intervals for all outcome domains. This reinforces the notion that the clinical imperative for extreme speed should be balanced against other factors, as an indiscriminate rush may introduce other risks (as observed with inflammatory markers and NICU admissions) without improving primary endpoints.

Biological Basis of the DDI Threshold and Stress Mechanisms

This study observed that in the group with a DDI of ≤75 minutes, elevated levels of white blood cells and neutrophils indicated an increased perioperative stress response. When the DDI was extended to 90 minutes, maternal inflammatory markers tended to normalize; however, the proportion of neonates admitted to the NICU due to DDI-related factors remained significantly higher, and the rate of postoperative maternal fever increased more than tenfold (11.76% vs 0.94%, P = 0.003). This phenomenon suggests that excessive compression of preoperative preparation time may adversely affect anesthesia induction, aseptic procedures, and team coordination, thereby increasing the risks of tissue injury or infection. Furthermore, the study showed that a shorter DDI did not lead to reductions in intraoperative blood loss or surgical duration, supporting the notion that “speed” may come at the expense of “quality”. At the 90-minute threshold, the incidence of postoperative maternal fever was higher in the short DDI group, while core outcome indicators remained unchanged, further reinforcing this inference. The enhanced maternal inflammatory response induced by shortened DDI may be related to multiple biological mechanisms. Excessively compressed preparation time could activate maternal acute stress responses, similar to what has been indicated by the release of copeptin—a stress biomarker—demonstrating fetal stress mechanisms.^1,2 Mothers may also experience a cascade of stress responses, leading to hyperactivation of the hypothalamic-pituitary-adrenal (HPA) axis.¹⁹ Rapid anesthesia induction and tissue trauma during surgery promote the release of pro-inflammatory cytokines such as interleukin-6 and tumor necrosis factor-alpha, which further mobilize and activate white blood cells and neutrophils.^20–22 Conversely, too brief a preparation period may provoke an overactive stress response, while excessively long intervals increase the risk of intrauterine hypoxia for the fetus. Therefore, in the high-risk setting of a positive OCT, it is crucial to carefully balance the benefits of timing against the potential stress-related risks.

To clarify the potential link to iatrogenic stress responses within compressed DDI windows: In clinical practice, achieving a DDI of ≤75 or even ≤90 minutes under emergency conditions often necessitates abbreviating or omitting several standardized procedures. This may include: (1) Abbreviated preoperative assessment and patient optimization, reducing time for comprehensive evaluation and informed consent; (2) Rushed anesthesia induction and monitoring setup, potentially compromising optimal dosing, positioning, and hemodynamic stability; (3) Condensed surgical “time-out” and team briefing, which are critical for ensuring shared situational awareness and contingency planning; and (4) Increased pressure on surgical pace, possibly leading to less meticulous tissue handling. We hypothesize that this cascade of compressed, high-stakes decision-making and execution—rather than the surgical technique itself—creates a state of heightened physiological stress for both the mother and the care team. This systemic stress may manifest as the elevated inflammatory markers and higher rates of complications observed in our shorter DDI groups, providing a plausible clinical pathway for the “iatrogenic stress response” mechanism proposed.

Importance of Individualized Clinical Decision-Making

This study reveals a critical finding: the adverse outcomes observed in the DDI ≤75-minute group showed no significant association with traditional perinatal risk factors, such as maternal age, gravidity, parity, or BMI (all P > 0.05). This observation has important clinical implications, suggesting that the adverse maternal and neonatal outcomes associated with short DDI are not attributable to inherent high-risk patient characteristics but are more likely related to iatrogenic stress responses triggered by the compression of decision-making time itself. This finding is corroborated by recent evidence-based studies. Prior research has confirmed that a slight extension of DDI does not worsen neonatal outcomes,^16–18 whereas neonatal perinatal mortality increases when DDI exceeds 90 minutes.²³ Collectively, these pieces of evidence, consistent with our results, support a crucial conclusion: in high-risk contexts such as a positive OCT, cesarean delivery decisions should not be mechanistically bound to a fixed time threshold. Instead, they should involve an individualized assessment that integrates real-time fetal heart rate monitoring data, maternal stress status, and the availability of medical resources.

This study highlights a noteworthy “time compression paradox”: when the anticipated DDI is likely less than 75 minutes, excessively compressing physiological preparation and compensatory time may paradoxically lead to worse maternal and neonatal outcomes.^24,25 A positive OCT inherently indicates fetal stress; further shortening of DDI under such pre-existing stress conditions may generate a “dual-stress overlay effect”, combining primary stress from intrauterine hypoxia with secondary stress from hurried medical intervention. Shorter DDI may also limit intrauterine resuscitation time. Our dual-threshold analysis (75 vs 90 minutes) clearly demonstrates that, in high-risk scenarios such as a positive OCT, solely emphasizing DDI reduction not only fails to improve maternal-neonatal outcomes²⁶ but may also provoke additional stress responses. The underlying mechanism of this “acceleration paradox” is that compressing physiological compensatory time transforms the intervention itself into a new stressor, triggering inflammatory cascades that ultimately negate the potential benefits of time savings.

We recommend that, for high-risk cases with a positive OCT, the decision to proceed with cesarean delivery should adopt a multidimensional, individualized evaluation model that comprehensively considers the following key elements:

(1) Dynamic changes in real-time fetal heart rate monitoring data, focusing not only on the static positive OCT result but more importantly on the degree of fetal heart rate deceleration and the normality of variability;^27–29 (2) Objective assessment of maternal stress, utilizing indicators such as inflammatory markers and vital sign changes to evaluate maternal stress levels; (3) Rational allocation of medical resources, ensuring efficient use without compromising quality of care; (4) Adequate implementation of intrauterine resuscitation measures, actively employing strategies such as left lateral positioning, maternal oxygen therapy, and discontinuation of oxytocin within the permissible DDI window.

Maternal and Neonatal Outcomes

The findings of this study provide important validation and extension of previous research regarding the impact of DDI on maternal and neonatal outcomes following a positive OCT. We observed that, after a positive OCT, the proportion of neonates transferred to the NICU due to DDI-related reasons was significantly higher in the short DDI groups (≤75 minutes and ≤90 minutes), despite no significant differences in major perinatal outcomes such as asphyxia rates. This is consistent with our overall results, which showed no significant differences in key maternal and neonatal outcomes between the 75-minute and 90-minute thresholds, suggesting that, within reasonable limits, moderate prolongation of DDI does not markedly increase perinatal risks and may instead offer a crucial window for optimizing preoperative assessment and team readiness.

Furthermore, we noted that postoperative inflammatory markers—specifically white blood cell and neutrophil counts—were significantly elevated in the short DDI group. Supporting this, a meta-analysis indicated that continuous oxytocin infusion increases the risk of uterine overstimulation (RR=0.45, 95% CI 0.34–0.60), which can potentially provoke maternal stress and inflammatory responses.³⁰ Although our study did not directly monitor contraction frequency, the rise in white blood cell and neutrophil counts may reflect the physiological burden imposed by more vigorous uterine stimulation and the increased urgency of surgical intervention in cases with extremely short DDI.

In summary, these findings suggest that, in cases with a positive OCT, moderately extending DDI to allow for fetal tolerance assessment and adequate preoperative preparation may be more advantageous than rigidly pursuing an extremely short interval. This approach may help mitigate maternal stress and inflammation, especially considering the higher NICU admission rates observed in the short DDI groups.

Limitations

The interpretation of the results should be approached with caution due to the retrospective, single-center design and the relatively limited sample size of this study. Clinical application should consider specific contexts, institutional capabilities, and individual patient characteristics. The study has several limitations: The retrospective design restricts the ability to fully control for confounding factors, and selection bias may be present. The single-center setting may limit the generalizability of the findings. Sample size constraints, particularly for some subgroup analyses, lead to limited statistical power. The absence of long-term follow-up hampers assessment of maternal and neonatal long-term outcomes. Intrauterine resuscitation measures were not standardized, and variations in management among different physicians may exist.

Prospects

Conduct prospective randomized controlled trials to compare the effects of different DDI strategies. Foster multicenter collaborations to enlarge sample sizes, enhance result reliability, and improve generalizability. Standardize intrauterine resuscitation protocols and evaluate their effectiveness. Incorporate long-term follow-up to assess the impact of DDI on children’s neurodevelopmental outcomes. Perform cost-effectiveness analyses from a health economics perspective to evaluate different strategies.

Conclusion

In conclusion, based on our data, we observed that among women with a positive OCT, a short DDI (≤75 minutes) did not significantly improve major maternal or neonatal outcomes and was associated with increased postoperative inflammatory responses and a higher risk of NICU admission. The analysis using a 90-minute threshold showed similar trends. These findings highlight the complexity of DDI management and underscore the need for further prospective investigations to determine the optimal DDI.