Fixation of levonorgestrel⁃releasing intrauterine system prevents its expulsion or malposition 

YANG Hong, LAN Ruihong, WANG Li, SONG Jie, HUANG Tengmin, GONG Humin.
The Journal of Practical Medicine . 2021, (13): 1706 -1710 .  DOI: 10.3969/j.issn.1006⁃5725.2021.13.012