A modified fetal heart rate tracing interpretation system for prediction of cesarean section.

OBJECTIVE

To investigate whether a modified version of the 2008 National Institute of Child Health and Human Development (NICHD) interpretation system upon admission decreases cesarean delivery risk.

METHODS

This retrospective cohort study ascribed a modified category to the first 30 min of fetal heart rate (FHR) tracings in labor. Category I was divided into two subsets (Ia and Ib) by the presence of accelerations. Category II was divided into four subsets (IIa-IId) based on baseline FHR, variability, response to stimulation and decelerations. Log-binomial regression was used to calculate risk ratios (RR) and 95% confidence intervals (CI).

RESULTS

A category was ascribed to 910 women. Most FHR tracings were Category Ia (65.8%), Ib (7.7%), IIb (11.8%) and IId (14.0%). Category Ib tracings (fewer than two accelerations) were 2.26 (95% CI: 1.13-4.52) times more likely to result in cesarean delivery for abnormal FHR tracing than Category Ia tracings. A similar increase in risk was seen when comparing Category IIb and Category IId with Category Ia.

CONCLUSION

Application of a modified version of the 2008 NICHD FHR interpretation system to the initial 30 min of labor can identify women at increased risk of cesarean delivery for abnormal FHR tracing.