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An attempt to improve recognition of fetal acidemia by a remodeled intrapartum cardiotocography classification : A case–control study

Fogelberg, Maria LU ; Bjurström, Johanna Wagner LU orcid ; Dahlbäck, Charlotte LU ; Ekengård, Frida LU ; Rickle, Gisela LU ; Källén, Karin LU and Herbst, Andreas LU (2026) In Acta Obstetricia et Gynecologica Scandinavica 105(9). p.1749-1760
Abstract

Introduction: Current international (FIGO) and Swedish cardiotocography (CTG) interpretation templates exhibit limited diagnostic accuracy for the detection of fetal acidemia. The objective of this study was to develop a novel intrapartum CTG classification template incorporating CTG parameters demonstrated to be strongly associated with acidemia, and to evaluate the diagnostic performance of the models by assessing their sensitivity and specificity in identifying CTG recordings from neonates with acidemia. Material and Methods: A retrospective case–control study based on 1092 births in Region Skåne. The study material included 364 cases with umbilical cord blood pH <7.05, or <7.10 after 1st stage cesarean, and 728 controls with... (More)

Introduction: Current international (FIGO) and Swedish cardiotocography (CTG) interpretation templates exhibit limited diagnostic accuracy for the detection of fetal acidemia. The objective of this study was to develop a novel intrapartum CTG classification template incorporating CTG parameters demonstrated to be strongly associated with acidemia, and to evaluate the diagnostic performance of the models by assessing their sensitivity and specificity in identifying CTG recordings from neonates with acidemia. Material and Methods: A retrospective case–control study based on 1092 births in Region Skåne. The study material included 364 cases with umbilical cord blood pH <7.05, or <7.10 after 1st stage cesarean, and 728 controls with pH ≥7.15 and Apgar scores ≥9 at 5 and 10 min. CTG patterns were systematically evaluated across a set of predefined variables, and associations between specific patterns and fetal acidemia were quantified using ORs. Two models defining pathological patterns were created: Model 1 based on the presence of one of several listed criteria resulting in a positive test and Model 2 also including the presence of ≥2 B-criteria resulting in a positive test. The main outcomes, sensitivity, and specificity to identify fetal acidemia at birth were calculated and compared with the current FIGO, NICE, and SWE guidelines. Results: The sensitivity to identify fetal acidemia was 86.3%, 86.5%, 50.8%, 57.1%, and 87.4% for Model 1, Model 2, FIGO, SWE, and NICE, respectively. The corresponding specificity was 77.9%, 76.4%, 92.6%, 91.2%, and 70.6%. The sensitivity to identify severe acidemia (pH <7.0) was 90.4% for Model 1 and for NICE; 64.4% for SWE, and 56.7% for FIGO. A variable not included in current classification systems, “fetal heart rate below baseline for >50% of the time during 30 minutes” was the criterion contributing most to the sensitivity. Conclusions: Our models show higher sensitivity but lower specificity for the defined outcome compared with SWE and FIGO, and similar sensitivity but higher specificity compared with NICE. Validating the model on a new material is essential before considering clinical use.

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author
; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
acidemia, Cardiotocography, electronic fetal monitoring, fetal heart rate, interpretation template
in
Acta Obstetricia et Gynecologica Scandinavica
volume
105
issue
9
pages
12 pages
publisher
Wiley-Blackwell
external identifiers
  • scopus:105041423768
  • pmid:42272108
ISSN
0001-6349
DOI
10.1111/aogs.70287
language
English
LU publication?
yes
id
d5df1fdd-76b5-4765-ac9a-f589d476a2d4
date added to LUP
2026-09-21 15:34:17
date last changed
2026-09-22 03:00:03
@article{d5df1fdd-76b5-4765-ac9a-f589d476a2d4,
  abstract     = {{<p>Introduction: Current international (FIGO) and Swedish cardiotocography (CTG) interpretation templates exhibit limited diagnostic accuracy for the detection of fetal acidemia. The objective of this study was to develop a novel intrapartum CTG classification template incorporating CTG parameters demonstrated to be strongly associated with acidemia, and to evaluate the diagnostic performance of the models by assessing their sensitivity and specificity in identifying CTG recordings from neonates with acidemia. Material and Methods: A retrospective case–control study based on 1092 births in Region Skåne. The study material included 364 cases with umbilical cord blood pH &lt;7.05, or &lt;7.10 after 1st stage cesarean, and 728 controls with pH ≥7.15 and Apgar scores ≥9 at 5 and 10 min. CTG patterns were systematically evaluated across a set of predefined variables, and associations between specific patterns and fetal acidemia were quantified using ORs. Two models defining pathological patterns were created: Model 1 based on the presence of one of several listed criteria resulting in a positive test and Model 2 also including the presence of ≥2 B-criteria resulting in a positive test. The main outcomes, sensitivity, and specificity to identify fetal acidemia at birth were calculated and compared with the current FIGO, NICE, and SWE guidelines. Results: The sensitivity to identify fetal acidemia was 86.3%, 86.5%, 50.8%, 57.1%, and 87.4% for Model 1, Model 2, FIGO, SWE, and NICE, respectively. The corresponding specificity was 77.9%, 76.4%, 92.6%, 91.2%, and 70.6%. The sensitivity to identify severe acidemia (pH &lt;7.0) was 90.4% for Model 1 and for NICE; 64.4% for SWE, and 56.7% for FIGO. A variable not included in current classification systems, “fetal heart rate below baseline for &gt;50% of the time during 30 minutes” was the criterion contributing most to the sensitivity. Conclusions: Our models show higher sensitivity but lower specificity for the defined outcome compared with SWE and FIGO, and similar sensitivity but higher specificity compared with NICE. Validating the model on a new material is essential before considering clinical use.</p>}},
  author       = {{Fogelberg, Maria and Bjurström, Johanna Wagner and Dahlbäck, Charlotte and Ekengård, Frida and Rickle, Gisela and Källén, Karin and Herbst, Andreas}},
  issn         = {{0001-6349}},
  keywords     = {{acidemia; Cardiotocography; electronic fetal monitoring; fetal heart rate; interpretation template}},
  language     = {{eng}},
  number       = {{9}},
  pages        = {{1749--1760}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Acta Obstetricia et Gynecologica Scandinavica}},
  title        = {{An attempt to improve recognition of fetal acidemia by a remodeled intrapartum cardiotocography classification : A case–control study}},
  url          = {{http://dx.doi.org/10.1111/aogs.70287}},
  doi          = {{10.1111/aogs.70287}},
  volume       = {{105}},
  year         = {{2026}},
}