Strengths and limitations
The strengths of our study include the large cohort size that allows
classification of LM population according to different causes, and
specific populations confined to women who had only one LM after the
first embryo transfer to eliminate other confounding factors as
possible. In addition, there were also several limitations in our study.
First, this study was limited by the retrospective design from a single
center, including missing data, potential recording bias.
Second,
the sample sizes were relatively limited in some subgroups, such as feLM
and trLM group, which
may
have a bearing on the statistical accuracy. Last, the causes of LM were
only categorized into embryonic, cervical, traumatic and unexplained
factors, more specific categorizations with clearer etiology are still
needed in future studies.