BJOG : an international journal of obstetrics and gynaecology
April 22, 2026 · via Europe PMC
Antenatal Prediction of Shoulder Dystocia and Birth Trauma Using Routine Maternal and Ultrasound Variables: Retrospective Cohort Study.
Schwartz A, Minopoli M, Di Ilio C, Di Mascio D, Bhide A, Thilaganathan B.
AI summary — for doctors, generated from the abstract only
A UK study developed antenatal prediction models for shoulder dystocia and birth trauma that modestly outperformed estimated fetal weight thresholds currently used in practice, though overall discrimination remained limited.
What was studied
A retrospective cohort study at a single UK tertiary referral center including 24,334 singleton term liveborn pregnancies (Jan 2016-Nov 2024) with a third-trimester ultrasound at or beyond 36 weeks, developing multivariable logistic regression models using maternal characteristics and fetal biometry (abdominal circumference and estimated fetal weight) to predict shoulder dystocia and a composite birth trauma outcome, with performance assessed by AUC and calibration.
Key findings
- 432 pregnancies (1.8%) were complicated by shoulder dystocia and 1,210 (5.0%) by birth trauma.
- The best model (maternal characteristics plus abdominal circumference centile) achieved AUC of 0.706 (95% CI 0.682-0.730) for shoulder dystocia (optimism-corrected 0.699) and AUC of 0.669 (95% CI 0.654-0.685) for birth trauma (optimism-corrected 0.665).
- At a 10% false-positive rate, sensitivity was 31.5% for shoulder dystocia and 22.8% for birth trauma using the new model, compared with 20.4% and 14.0% respectively using the currently used estimated fetal weight ≥90th centile threshold.
Clinical relevance
The findings suggest that combining fetal abdominal circumference centile with maternal risk factors may offer modestly better antenatal risk stratification for shoulder dystocia and birth trauma than current estimated fetal weight thresholds, potentially useful for counseling, though the authors emphasize this should not replace clinical judgment as a stand-alone test.
Who should care
Limitations
Discrimination for both models remained modest (AUC under 0.71), meaning many cases would still be missed or falsely flagged, and this was a single-center retrospective study that may not generalize to other populations or practice settings.
A new antenatal model combining fetal abdominal circumference with maternal risk factors modestly outperforms current estimated-fetal-weight-based thresholds for predicting shoulder dystocia and birth trauma, but discrimination remains limited.
This is an AI-generated summary of the published abstract, not a clinical recommendation. It may not reflect the full text or subsequent updates — verify against the original source before acting on it.
Abstract
Objective
To develop antenatal prediction models for shoulder dystocia and birth trauma using routinely collected maternal and sonographic variables.
Design
Retrospective cohort study.
Setting
Single tertiary referral centre in the UK.
Population or sample
All singleton term liveborn pregnancies delivered between January 2016 and November 2024 with a third-trimester ultrasound performed at or beyond 36 weeks' gestation.
Methods
Multivariable logistic regression was used to develop antenatal prediction models for shoulder dystocia and birth trauma, incorporating maternal characteristics and fetal biometry including abdominal circumference (AC; centile or mm) and estimated fetal weight (EFW; grams or centile). Model performance was assessed using tests for multicollinearity, discrimination (area under the ROC curve, AUC) and calibration.
Main outcome measures
Shoulder dystocia and birth trauma, the latter defined as a composite of shoulder dystocia, postpartum haemorrhage requiring blood transfusion, caesarean delivery at full dilatation, or hypoxic-ischaemic encephalopathy (HIE ≥ 1).
Results
A total of 24 334 singleton term pregnancies were included; 432 (1.8%) were complicated by shoulder dystocia and 1210 (5.0%) by birth trauma. The model including maternal characteristics and AC centile demonstrated the best discrimination. For shoulder dystocia, the apparent AUC was 0.706 (95% CI 0.682-0.730); the optimism-corrected AUC after bootstrap validation was 0.699. For birth trauma, the apparent AUC was 0.669 (95% CI 0.654-0.685); the optimism-corrected AUC was 0.665. At a 10% false-positive rate, sensitivity was 31.5% for shoulder dystocia and 22.8% for birth trauma, compared with 20.4% and 14.0%, respectively, using EFW ≥ 90th centile.
Conclusions
Antenatal models combining fetal AC centile with maternal risk factors outperform EFW-based thresholds currently used in clinical practice. Although discrimination was modest, the model may be useful for antenatal risk stratification and counselling, rather than as a stand-alone clinical test. Such models may help identify pregnancies at increased risk of delivery-related complications associated with fetal overgrowth and inform future studies evaluating targeted interventions.
DOI
10.1111/1471-0528.70250
PMID
42020345
PMCID
PMC13571882
Research metadata (titles, abstracts, authors, publication dates) is sourced from Europe PMC, which aggregates content from PubMed/MEDLINE, PubMed Central, and other providers under the U.S. National Library of Medicine (NLM/NCBI). NLM does not claim copyright on abstracts; the original journal publishers or authors may hold rights to the full articles. AI-generated summaries are derived only from the abstract, never the full text, and are always labeled as AI-generated.
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