Risk factors for mortality and severe morbidity in fetuses with normal late third-trimester scan: population-based cohort study

E D'Alberti; S Dockree; M Garbagnati; C Granieri; A Cavallaro; L Impey

doi:10.1002/uog.29256

Risk factors for mortality and severe morbidity in fetuses with normal late third-trimester scan: population-based cohort study

Ultrasound Obstet Gynecol. 2025 Jul;66(1):56-64. doi: 10.1002/uog.29256. Epub 2025 Jun 16.

Authors

E D'Alberti^{1

2

3}, S Dockree¹, M Garbagnati^{1

2}, C Granieri^{1

2

4}, A Cavallaro¹, L Impey^{1

2}

Affiliations

¹ Women's Centre, John Radcliffe Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, UK.
² Nuffield Department of Women's & Reproductive Health, University of Oxford, University of Oxford, Oxford, UK.
³ Department of Maternal and Child Health and Urological Sciences, Sapienza University of Rome, Rome, Italy.
⁴ Department of Obstetrics and Gynecology, Università Cattolica del Sacro Cuore, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy.

Abstract

Objective: To identify antepartum risk factors for fetal or neonatal mortality and severe morbidity in pregnancies undergoing a universal late third-trimester ultrasound scan in which there was no ultrasound evidence of small-for-gestational age (SGA) or fetal growth restriction (FGR).

Methods: This was a retrospective population-based cohort study of singleton, non-anomalous term pregnancies undergoing a universal ultrasound scan at 35 + 1 to 36 + 6 weeks' gestation at a major UK maternity unit, over a period of 7 years. Pregnancies complicated by SGA or FGR were excluded. The outcomes were: stillbirth; severe composite adverse outcome, including extended perinatal mortality and severe morbidity; and severe SGA, defined as birth weight < 3^rd centile. Potential clinical, demographic and ultrasonographic risk factors were evaluated using univariate and multivariate logistic regression analysis.

Results: The study population of 40 169 pregnancies comprised 88.9% of all eligible term pregnancies. There were 48 (0.1%) stillbirths, 221 (0.6%) cases of severe composite adverse outcome and 295 (0.7%) cases of severe SGA. Five (10.4%) stillborn infants weighed < 10^th centile at delivery (adjusted odds ratio (aOR), 2.70 (95% CI, 1.06-6.92)); 23 (47.9%) cases of stillbirth were considered unexplained. Pre-eclampsia was associated with stillbirth (odds ratio, 4.46 (95% CI, 1.99-9.96)) but no other antenatal factors, including ultrasound measures of fetal growth, showed a significant association with this outcome. Pre-eclampsia constituted 9.6% of the population-attributable fraction for stillbirth. Severe composite adverse outcome was associated only with pre-existing diabetes (aOR, 2.82 (95% CI, 1.02-7.85)) and nulliparity (aOR, 1.56 (95% CI, 1.19-2.04)).

Conclusions: The potential to predict mortality and severe morbidity in fetuses without ultrasound evidence of SGA and FGR is poor. In these fetuses, the role of ultrasound in further reducing adverse outcomes at term is limited. © 2025 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Keywords: adverse perinatal outcome; antepartum surveillance; stillbirth; universal scan.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adult
Cohort Studies
Female
Fetal Growth Retardation* / diagnostic imaging
Fetal Growth Retardation* / mortality
Gestational Age
Humans
Infant, Newborn
Infant, Small for Gestational Age
Perinatal Mortality
Pregnancy
Pregnancy Outcome
Pregnancy Trimester, Third
Retrospective Studies
Risk Factors
Stillbirth / epidemiology
Ultrasonography, Prenatal* / statistics & numerical data
United Kingdom / epidemiology