Cutoffs that Count: Insights into Receiver Operating Characteristic Curves for Cord Blood pH, Lactate, and Base...

Reading heart rate patterns during labor (cardiotocography) can be difficult and does not always predict when babies develop acid buildup in their blood, especially when oxygen levels drop quickly during delivery. In India, we lack enough research comparing these heart rate patterns with blood chemistry tests from the umbilical cord, making it harder for doctors to make the best decisions during childbirth.

We wanted to study how abnormal heart rate patterns during labor relate to blood chemistry levels in the umbilical cord. Our goal was to find better ways to use lactate levels and improve delivery timing for Indian women having cesarean sections.

We conducted this study at All India Institute of Medical Sciences Raipur, from April 2019 to January 2021, following 85 pregnant women at full term who needed emergency cesarean sections. We classified heart rate patterns using standard medical guidelines (National Institute of Child Health and Human Development criteria). Within 45 s of delivery, we collected blood samples from the umbilical cord to test pH, lactate, and base excess levels. We used statistical analysis to find the best cutoff values for diagnosis. Our main focus was on how heart rate patterns related to cord blood pH levels, with secondary attention to lactate and base excess connections.

Out of 85 women (43 with concerning heart rate patterns and 42 with normal patterns), we found strong connections between abnormal heart rate patterns and acidic blood in the cord (pH <7.2: 37.2% vs. 9.5%, P = 0.003; lactate > 4 mmol/L: 41.9% vs. 16.7%, P = 0.017). Our analysis showed the best diagnostic levels were pH 7.035 (97.6% sensitivity and 97.7% specificity) and lactate 1.55 mmol/L (95.2% sensitivity and 93.0% specificity). The most severe heart rate patterns (Category III) had the highest rates of blood acidity (55.6%). When delivery took longer than 30 min after the medical team made the decision, babies had higher risks of developing acidosis (P = 0.036). Lactate levels proved more accurate for diagnosis than pH or base excess measurements.

Abnormal heart rate patterns during labor are strongly linked to acidic blood conditions in Indian babies. Using improved lactate cutoff levels (1.55 mmol/L) provides better accuracy than traditional pH measurements. Quick delivery (within 30 min) for the most severe heart rate patterns, combined with lactate-guided blood tests, could improve outcomes for mothers and babies in hospitals with limited resources.