Making the diagnosis of non-reassuring fetal status: Potential for implicit bias


      Nearly a quarter of cesarean deliveries (CD) are performed for non-reassuring fetal status (NRFS), a diagnosis lacking standardized and reproducible definitions. NRFS is potentially susceptible to subjective judgements in areas prone to bias in healthcare, such as obesity and race. We assessed differences in rates of CD for NRFS between patients with and without obesity stratified by race.

      Study Design

      This was a secondary analysis of a prospective cohort of term, singleton pregnancies admitted for labor or induction of labor. The primary outcome was CD for NRFS, defined as CD with any indication for NRFS. The secondary outcomes were CD or operative vaginal delivery (OVD) for the sole indication of NRFS. These outcomes and the occurrence of composite high risk Category II features 60 mins before delivery (minimal variability, tachycardia, recurrent lates or variables, or >1 prolonged deceleration) were compared between patients with and without obesity. Electronic fetal monitoring (EFM) data were collected by providers blinded to BMI. Multivariable logistic regression was used to adjust for confounders. Results were stratified by race.


      Of 8580 women, 4825 (56%) were obese. Patients with obesity had a 79% increased risk of CD for NRFS compared to those without obesity (aRR 1.79, 95%CI 1.56-2.06). This association remained significant for the outcomes of CD or any OVD for the sole indication of NRFS. Composite high risk Category II features was similar between the two groups in the entire cohort and in the subgroup of patients undergoing CD for NRFS. Both Black and White women with obesity were at higher risk of CD for NRFS compared to their non-obese counterparts but the risk was significantly higher among Black women (aRR 1.78, 95% CI 1.51-2.10 vs aRR 1.62, 95% CI 1.18-2.21, P interaction- < 0.001).


      Patients with obesity are at increased risk of CD for NRFS despite no differences in Category II features. This effect is further modified by race. While residual confounders are possible, these results suggest a possible element of implicit bias in the diagnosis of NRFS.
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