title: DNA shotgun sequencing of cervical swab: cervical insufficiency
design: Total DNA was extracted from the cervical swab using Maxwell 16 LEV Blood DNA Kit. Each DNA library was prepared by the TruSeq Nano DNA sample preparation kit according to manufacturer's instruction. Each library was paired end sequenced by HiSeq X system. Raw sequence reads less than 50 bp and low quality (Phred Score of 20) were trimmed. After quality trimming, reads aligned to the human reference genome (GRCh38) were removed. Finally, clean reads mostly derived from microorganisms were used for the diverse metagenomic analyses.