[Evaluation of the CNGOF foetal heart rate classification]

The 2007 CNGOF guidelines for good practice on "Methods of foetal surveillance during labour" proposed a consensual definition of intra-partum foetal heart rate (FHR) patterns. In order to facilitate its application, Carbon et al. published in 2013 a simplified table of the classification with 5 types of tracing.

To evaluate the diagnosis value of this FHR classification to determine the risk of foetal acidosis.

Retrospective single-centre study including 252 single pregnancies beyond 34 weeks of gestation with a record of at least 60minutes before delivery. The primary endpoint was a pH at birth < 7.20.

When pH was < 7.20, type 3 tracing was significantly more frequent during the first stage of labour while types 4 and 5 were more frequently found during active second stage. A pH<7.20 was significantly associated with more instrumental extractions, emergency caesarean section, Apgar score < 7 and neonatal respiratory distress. The areas under the curve were 0.63 for the analysis during the first stage of labour, 0.69 for second stage, and 0.68 when the two stages were combined.

Our study found that the CNGOF classification improved the FHR interpretation but its diagnosis value to predict acidosis remained limited.