Article Text

Download PDFPDF

Revealed versus concealed criteria for placental insufficiency in an unselected obstetric population in late pregnancy (RATIO37): randomised controlled trial study protocol
  1. Francesc Figueras1,2,
  2. Eduard Gratacos1,2,
  3. Marta Rial1,2,
  4. Ilan Gull3,
  5. Ladislav Krofta4,
  6. Marek Lubusky5,
  7. Cruz-Martinez Rogelio6,
  8. Cruz-Lemini Mónica6,
  9. Martinez-Rodriguez Miguel6,
  10. Pamela Socias7,
  11. Cristina Aleuanlli7,
  12. Mauro C Parra Cordero7
  1. 1 Fetal i+D Fetal Medicine Research Center, BCNatal - Barcelona Center for Maternal-Fetal and Neonatal Medicine (Hospital Clínic and Hospital Sant Joan de Deu), IDIBAPS, University of Barcelona, Barcelona, Spain
  2. 2 Centre for Biomedical Research on Rare Diseases (CIBER-ER), Barcelona, Spain
  3. 3 Lis Hospital for Women, Tel Aviv University, Tel Aviv, Israel
  4. 4 Institute for the care of mother and child, Third Faculty of Medicine, Charles University, Prague, Czech Republic
  5. 5 Departmente of Obstetrics and Gynecology, Palacky University Olomouc, Faculty of Medicine and Dentistry, University Hospital Olomouc, Olomouc, Czech Republic
  6. 6 Unidad de Investigación en Medicina y Cirugía Fetal, Hospital de Especialidades del Niño y la Mujer de Querétaro. Unidad de Investigación en Neurodesarrollo, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM) campus Juriquilla, Querétaro, México
  7. 7 Department of Obstetrics and Gynecology, Fetal Medicine Unit, University of Chile Hospital, Santiago, Chile
  1. Correspondence to Dr Francesc Figueras; ffiguera{at}


Introduction Fetal growth restriction (FGR) affects 5%–10% of all pregnancies, contributing to 30%–50% of stillbirths. Unfortunately, growth restriction often is not detected antenatally. The last weeks of pregnancy are critical for preventing stillbirth among babies with FGR because there is a pronounced increase in stillbirths among growth-restricted fetuses after 37 weeks of pregnancy. Here we present a protocol (V.1, 23 May 2016) for the RATIO37 trial, which evaluates an integrated strategy for accurately selecting at-risk fetuses for delivery at term. The protocol is based on the combination of fetal biometry and cerebroplacental ratio (CPR). The primary objective is to reduce stillbirth rates. The secondary aims are to detect low birth weights and adverse perinatal outcomes.

Methods and analysis The study is designed as multicentre (Spain, Chile, Mexico,Czech Republic and Israel), open-label, randomised trial with parallel groups. Singleton pregnancies will be invited to participate after routine second-trimester ultrasound scan (19+0–22+6 weeks of gestation), and participants will be randomly allocated to receive revealed or concealed CPR evaluation. Then, a routine ultrasound and Doppler scan will be performed at 36+0–37+6 weeks. Sociodemographic and clinical data will be collected at enrolment. Ultrasound and Doppler variables will be recorded at 36+0–37+6 weeks of pregnancy. Perinatal outcomes will be recorded after delivery. Univariate (with estimated effect size and its 95% CI) and multivariate (mixed-effects logistic regression) comparisons between groups will be performed.

Ethics and dissemination The study will be conducted in accordance with the principles of Good Clinical Practice. This study was accepted by the Clinical Research Ethics Committee of Hospital Clinic Barcelona on 23May 2016. Subsequent approval by individual ethical committees and competent authorities was granted. The study results will be published in peer-reviewed journals and disseminated at international conferences.

Trial registration number NCT02907242; pre-results.

  • Fetal medicine
  • Ultrasonography
  • Placental insufficiency

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


  • Contributors MR is the project monitor, contributed to the study planning and will participate in the report of the data. RC, MP, ML and LK are coordinators at their respective sites, contributed to the study planning and will participate in the report of the data. MC and MM contributed to the conducting and will report the data. FF is the general coordinator and PI of the project. EG is co-principal investigator of the study.

  • Funding The study was funded by the Erasmus+ Programme of the European Union (Framework Agreement number: 2013-0040).

  • Competing interests None declared.

  • Ethics approval Hospital Clinic Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

Linked Articles