**5. Conclusions**

Transvaginal sonographic detection of cervical funneling in the second trimester of pregnancy is the most important marker for the prediction of preterm labor. Arabin pessary (probably in combination with progesterone) seems to be effective in its prevention. Further multicenter studies are necessary to confirm these findings and determine as guidelines in the future.

**Author Contributions:** For research articles with several authors, a short paragraph specifying their individual contributions must be provided. The following statements should be used. Roland Csorba, George Iatrakis, Stefanos Zervoudis, Georgios Galazios and Alexander-Tobias Teichmann conceived and designed the experiments; performed the experiments; Vasileios Maroulis, Anastasia Bothou, Anna Chalkidou, Dorelia Deuteraiou, Xanthoula Anthoulaki, Arzou Halil Bourazan, Lola-Katerina Inagamova and George Anastasopoulos, Georgios Tsatsaris. analyzed the data; George Anastasopoulos, Georgios Tsatsaris contributed reagents/materials/analysis tools; Panagiotis Tsikouras wrote the paper. Authorship must be limited to those who have contributed substantially to the work reported.

**Conflicts of Interest:** The authors declare no conflict of interest.
