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Updated: Oct 15, 2025
Transuterine Fetal Tracheal Occlusion Model in Mice
Published on: February 5, 2021
Second trimester fetal thymus size in association to preterm birth
Christian Porschen1, Ralf Schmitz1, Rene Schmidt2
1Department of Gynecology and Obstetrics, University Hospital Münster, Munster, Germany.
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.
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