ABX-30
Bacterial DNA extraction for microbiota analysis of endometrial lavage specimens was performed using a QiaAmp DNA Microbiome Kit (Qiagen, Hilden, Germany). The concentration and quality of purified DNA were assessed using the Qubit dsDNA High Sensitivity Assay (Thermo Fisher Scientific, Waltham, MA, USA). The protocol for library construction and sequencing has been previously described in detail [37]. In brief, a 16S rRNA gene amplicon library targeting the 16S rRNA V3V11 region was initially constructed. Illumina adaptor overhang nucleotide sequences were subsequently added to gene-specific sequences.