Second trimester fetal thymus size in association to preterm birth

Christian Porschen; Ralf Schmitz; Rene Schmidt; Kathrin Oelmeier; Kerstin Hammer; Maria Falkenberg; Janina Braun; Helen Ann Köster; Johannes Steinhard; Mareike Möllers

doi:10.1515/jpm-2021-0065

Second trimester fetal thymus size in association to preterm birth

J Perinat Med. 2021 Oct 27;50(2):144-149. doi: 10.1515/jpm-2021-0065. Print 2022 Feb 23.

Affiliations

¹ Department of Gynecology and Obstetrics, University Hospital Münster, Munster, Germany.
² Institute of Biostatistics and Clinical Research, University of Münster, Munster, Germany.
³ Fetal Cardiology, Heart and Diabetes Center NRW, Ruhr-University Bochum, Bad Oeynhausen, Germany.

PMID: 34710316
DOI: 10.1515/jpm-2021-0065

Abstract

Objectives: The aim of this study was to compare the second trimester thymus-thorax-ratio (TTR) between fetuses born preterm (study group) and those born after 37 weeks of gestation were completed (control group).

Methods: This study was conducted as a retrospective evaluation of the ultrasound images of 492 fetuses in the three vessel view. The TTR was defined as the quotient of a.p. thymus diameter and a.p. thoracic diameter.

Results: Fetuses that were preterm showed larger TTR (p<0.001) the second trimester than those born after 37 weeks of gestation were completed. The sensitivity of a binary classifier based on TTR for predicting preterm birth (PTB) was 0.792 and the specificity 0.552.

Conclusions: In our study, fetuses affected by PTB showed enlarged thymus size. These findings led us to hypothesize, that inflammation and immunomodulatory processes are altered early in pregnancies affected by PTB. However, TTR alone is not able to predict PTB.

Keywords: fetal diagnosis; pregnancy; prenatal ultrasonography; preterm birth; second trimester; ultrasound.

MeSH terms

Female
Fetus / diagnostic imaging
Humans
Infant, Newborn
Pregnancy
Pregnancy Trimester, Second
Premature Birth* / etiology
Retrospective Studies
Ultrasonography, Prenatal / methods