Implementation of a revised classification for intrapartum fetal heart rate monitoring and association to birth outcome: A national cohort study

Abstract

Introduction A revised intrapartum cardiotocography (CTG) classification was introduced in Sweden in 2017. The aims of the revision were to adapt to the international guideline published in 2015 and to adjust the classification of CTG patterns to current evidence regarding intrapartum fetal physiology. This study aimed to investigate adverse neonatal outcomes before and after implementation of the revised CTG classification. Material and Methods A before‐and‐after design was used. Cohort I (n = 160 210) included births from June 1, 2014 through May 31, 2016 using the former CTG classification, and cohort II (n = 166 558) included births from June 1, 2018 through May 31, 2020 with the revised classification. Data were collected from the Swedish Pregnancy and Neonatal Registers. The primary outcome was moderate to severe neonatal hypoxic ischemic encephalopathy (HIE 2–3). Secondary outcomes were birth acidemia (umbilical artery pH <7.05 and base excess < −12 mmol/L or pH <7.00), A‐criteria for neonatal hypothermia treatment, 5‐min Apgar scores <4 and <7, neonatal seizures, meconium aspiration, neonatal mortality and delivery mode. Logistic regression was used (period II vs period I), and results are presented as adjusted odds ratios (aORs) with 95% confidence intervals (95% CIs). Results There were no statistically significant differences in HIE 2–3 (aOR 1.27; 95% CI 0.97–1.66), proportion of neonates meeting A‐criteria for hypothermia treatment (aOR 0.96; 95% CI 0.89–1.04) or neonatal mortality (aOR 0.68; 95% CI 0.39–1.18) between the cohorts. Birth acidemia (aOR 1.36; 95% CI 1.25–1.48), 5‐min Apgar scores <7 (aOR 1.27; 95% CI 1.18–1.36) and <4 (aOR 1.40; 95% CI 1.17–1.66) occurred more often in cohort II. The absolute risk difference for HIE 2–3 was 0.02% (95% CI 0.00–0.04). Operative delivery (vacuum or cesarean) rates were lower in cohort II (aOR 0.82; 95% CI 0.80–0.85 and aOR 0.94; 95% CI 0.91–0.97, respectively). Conclusions Although not statistically significant, a small increase in the incidence of HIE 2–3 after implementation of the revised CTG classification cannot be excluded. Operative deliveries were fewer but incidences of acidemia and low Apgar scores were higher in the latter cohort. This warrants further in‐depth analyses before a full re‐evaluation of the revised classification can be made.

Comparison of fetal heart rate baseline estimation by the cardiotocograph network and clinicians: a multidatabase retrospective assessment study

“…Electronic fetal heart rate (FHR) monitoring was introduced to detect fetuses' pathological states as early as possible in the obstetrics practice in the late 1950s. However, the misinterpretation and ambiguity of FHR patterns may increase unnecessary interventions, such as operative deliveries and cesarean sections (2)(3)(4). Different guidelines over the past decades have recommended some modifications for interpreting FHR tracings, but beliefs in the etiology of basic FHR patterns (including the baseline, the variability, accelerations, decelerations, and sinusoidal patterns) have remained essentially unchanged (5,6).…”

The association between undetected small‐for‐gestational age and abnormal admission cardiotocography: A registry‐based study

“…In Sweden, 93–95% of all admCTG are normal 9 . An admCTG is performed immediately upon arrival before history taking and examination 1 .…”

“…In Sweden, 93-95% of all admCTG are normal. 9 An ad-mCTG is performed immediately upon arrival before history taking and examination. 1 If the first 20-30 minutes of a CTG are normal, a low-risk fetus is monitored by intermittent auscultation during labour.…”

Is the fetus fit for labor? Introducing fast‐and‐frugal trees (FFTrees) to simplify triage of women for STAN monitoring: An interobserver agreement comparison with traditional classification

“…2,3 The CTG interpretation is the weakest link in the STAN system and recent efforts to improve and simplify the CTG classification have not solved the problem, and possibly made it worse: after an update of the Swedish national guidelines in 2017, inspired by the new International Federation of Gynecology & Obstetrics (FIGO) guidelines from 2015 (FIGO2015), the national incidences of birth acidemia and low Apgar scores have worsened. 4,[5][6][7] The traditional CTG classification systems are based on visual "pattern recognition" and clustering of the different FHR element categories (baseline, variability, accelerations, decelerations) into a fixed matrix. 4,8,9 However, a traditional fixed matrix may not fit all situations, and an alternative fetal physiology-oriented classification has been proposed.…”

“…The CTG interpretation is the weakest link in the STAN system and recent efforts to improve and simplify the CTG classification have not solved the problem, and possibly made it worse: after an update of the Swedish national guidelines in 2017, inspired by the new International Federation of Gynecology & Obstetrics (FIGO) guidelines from 2015 (FIGO2015), the national incidences of birth acidemia and low Apgar scores have worsened 4,5–7 …”