Single versus longitudinal scans in the third trimester: a multicenter randomized clinical trial on screening for late-onset intrauterine fetal growth restriction (The RCT on Evaluation of LAte Iugr Screening study) - 19/12/25

Doi : 10.1016/j.ajog.2025.11.027

Alessandra Familiari, MD ^a,^⁎,^{^{1
F.A. and S.T. Joint first authors.}} , Tamara Stampalija, MD, PhD ^b,^c,^{^{1
F.A. and S.T. Joint first authors.}}, Federico Prefumo, MD, PhD ^d, Giulia di Marco, MD ^a, Maria Giulia Ferrante, MD ^a, Elisa Bevilacqua, MD, PhD ^a, Giulia Zamagni, MD, PhD ^e, Lorenzo Monasta, MD, PhD ^e, Grazia Tiralongo, MD ^f, Herbert Valensise, MD, PhD ^g,^h, Maddalena Morlando, MD, PhD ⁱ, Laura Sarno, MD, PhD ^j, Daniele Di Mascio, MD, PhD ^k, Ilenia Mappa, MD ^l, Giuseppe Rizzo, MD, PhD ^k, Silvia Visentin, MD, PhD ^m, Anna Fichera, MD, PhD ⁿ, Tatjana Radaelli, MD ^o, Baskaran Thilaganathan, MD, PhD ^p, Giovanni Scambia, MD, PhD ^a, Tullio Ghi, MD, PhD ^a,^{^{2
G.T. and F.E. Joint last authors.}}, Enrico Ferrazzi, MD, PhD ^o,^{^{2
G.T. and F.E. Joint last authors.}}
^a Department of Women and Child Health, Women Health Area, Fondazione Policlinico Universitario Agostino Gemelli, IRCCS, Università Cattolica del S. Cuore, Rome, Italy
^b Unit of Fetal Medicine and Prenatal Diagnosis, Institute for Maternal and Child Health, IRCCS Burlo Garofolo, Trieste, Italy
^c Department of Medicine, Surgery and Health Sciences, University of Trieste, Trieste, Italy
^d Obstetrics and Gynecology Unit, IRCCS Istituto Giannina Gaslini, Genova, Italy
^e Clinical Epidemiology and public Health research Unit Institute for maternal and child Health – IRCCS Burlo Garofolo, Trieste, Italy
^f Department of Obstetrics and Gynecology, Casilino General Hospital, Rome, Italy
^g Department of Surgical Sciences, University of Rome Tor Vergata, Rome, Italy
^h Department of Obstetrics and Gynecology, Casilino General Hospital, Rome, Italy
ⁱ Department of Woman, Child and General and Specialised Surgery, University of Campania “Luigi Vanvitelli”, Naples, Italy
^j Department of Neurosciences Reproductive Science and Dentistry, University Federico II, Naples, Italy
^k Department of Maternal and Child Health and Urological Sciences, Sapienza University of Rome, Rome, Italy
^l Department of Obstetrics and Gynecology Ospedale Cristo Re Roma, Rome, Italy
^m Department of Woman's and Child's Health, University of Padova, Padova, Italy
ⁿ Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy
^o Department of Woman, Child and Neonate, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, Milan, Italy
^p Fetal Medicine Unit, St George's University Hospitals NHS Foundation Trust and Vascular Biology Research Centre, Molecular and Clinical Sciences Research Institute, St George's University of London, London, UK

^∗Corresponding author: Alessandra Familiari.

Sous presse. Épreuves corrigées par l'auteur. Disponible en ligne depuis le Friday 19 December 2025

Abstract

Background

Undiagnosed fetal smallness is strongly associated with adverse perinatal outcomes. Despite robust evidence that late third trimester ultrasound improves small for gestational age detection, the question of whether routine ultrasound assessment in late pregnancy can improve perinatal outcome remains unresolved.

Objective

The objective of the study was to assess whether the addition of a 35 to 37–week scan in low-risk pregnancy would improve the detection of small for gestational age at birth without increasing cesarean section rates or neonatal morbidity.

Study design

Open label multicentric randomized trial recruiting nulliparous low-risk pregnant women in 10 Italian centers between January 2021 and March 2023. Patients were randomly assigned at mid-trimester scan to either routine care (single scan at 28–32 weeks) or intervention (routine care plus additional scan at 35–37 weeks). The primary endpoint was prenatal detection of small for gestational age neonate with birthweight <10th centile. Predefined secondary outcomes included detection of severe fetal smallness defined as birthweight <third centile, cesarean section rate, composite mild/severe adverse neonatal outcome, and intact neonatal survival. The study is registered at ClinicalTrials.gov (NCT05787054) on the first of March, 2023.

Results

The antenatal detection of small for gestational age birth was significantly higher in the intervention (9/46, sensitivity 19.5%) vs routine care (0/28, sensitivity 0%) arms of the trial ( P =.011). False positive rate for the intervention for the routine care arms were 1.7% and 2.0%, respectively. The total cesarean section rate was unchanged (odds ratio, 0.89; 95% confidence interval, 0.63–1.26) and the neonatal intensive care unit admission rate was significantly lower for patients allocated to have a scan at 35 to 37 weeks (3.8% vs 1.0%; odds ratio, 0.27 [95% confidence interval, 0.09–0.80]). Composite adverse neonatal outcomes and intact neonatal survival rates were not significantly different between 2 groups.

Conclusion

In a low-risk population performing an additional ultrasound scan at 35 to 37 weeks increases the detection of small for gestational age at birth and reduces the rate of neonatal intensive care unit admission without affecting rates of labor induction or total cesarean birth.

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Key words : fetal smallness, intrauterine growth restriction, late fetal growth restriction, third trimester screening

Plan

	The study is registered at ClinicalTrials.gov (NCT05787054) NCT05787054 on the first of March, 2023. The date of initial participant enrollment was in January 2021.
	The authors report no conflict of interest.
	This research was funded by Italian Society of Obstetrics and Gynecology (SIGO).
	Anonymized individual participant data, the study protocol, statistical analysis plan, and informed consent form will be available after publication via e-mail after approval of a proposal with a signed data access agreement.