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BackgroundChina had achieved impressive success in improving maternal health, while the progress of reducing maternal mortality ratio (MMR) varied across regions. Some studies had reported maternal mortality from national or provincial perspective, but researches of the MMR on long-term period at the city or county level rare been reported. Shenzhen has experienced significant socioeconomic and health changes, reflecting the typical development of China's coastal city. This study mainly introduced the levels and trends of maternal death in Baoan district, Shenzhen from 1999 to 2022.MethodsMaternal mortality data were extracted from registration forms and the Shenzhen Maternal and Child Health Management System. Linear-by-Linear Association tests were used to evaluate the trends of MMR among different groups. The study periods were divided into three stages by 8-year interval and χ2 test or Fisher's test was used to test the difference in maternal deaths of different periods.ResultsDuring 1999–2022, a total of 137 maternal deaths occurred in Baoan, the overall MMR was 15.91 per 100,000 live births, declined by 89.31% with an annualized rate of 9.26%. The MMR declined by 68.15% in migrant population, with an annualized rate of 5.07%, faster than that in permanent population (48.73%, 2.86%). The MMR due to direct and indirect obstetric causes shown a downward trend (PP < 0.01), pregnancy-induced hypertension became the leading cause of deaths during 2015–2022. The constituent ratio of maternal deaths with advanced age significantly increased by 57.78% in 2015–2022 compared with in 1999–2006.ConclusionsBaoan district had made encouraging progress in improving maternal survival, especially in migrant population. To further reduce the MMR, strengthening professional training to improve the capacity of obstetricians and physicians, increasing the awareness and ability of self-help health care among elderly pregnant women were in urgent need.

Additional file 7: Figure S6. Weighted (A) and unweighted (B) UniFrac distance-based beta diversity of the cow rumen microbial communities revealed by DNBSEQ and NovaSeq sequencing platforms.

Additional file 5: Figure S4. Comparison of the amplicon sequencing results of three typical ecological systems between DNBSEQ and NovaSeq sequencing platforms. (A) Evaluation of the reproducibility of the amplicon sequencing results of DNBSEQ and NovaSeq sequencing platform in revealing the accumulated relative abundance of microbes of abundant, moderate and rate taxa subcommunity from ecosystems with various complexity (DNB All, DNB 2, DNB 3 denotes number of all unique OTUs detected by DNBSEQ platform, consistently detected by at least 2 technical replicates, and consistently detected by all three technical replicates, respectively. Similar naming scheme was used for the NovaSeq platform). (B) Cross-verification of the OTUs identified by amplicon sequencing on DNBSEQ and NovaSeq platforms and shotgun sequencing results of the same set of mangrove sediment samples. (C) Cross-verification of the OTUs identified by amplicon sequencing on DNBSEQ and NovaSeq platforms and shotgun sequencing results of the same set of mice gut samples.

Additional file 2: Figure S1. Schematic presentation of the design and flow of this study. This study was designed to evaluate the potential harm of false positives introduced by index misassignment during the sequencing to the interpretation of metabarcoding or here amplicon sequencing studies. In part 1, mock communities with known microbial composition were used to confirm the presence of index misassignment introduced false positives and the rate of this misassignment on different sequencing platform; In part 2, samples from several typical ecosystems with various complexity were sequenced to test how index misassignment could affect the estimation of community diversity for different samples; In part 3, a case study using a set of cow rumen samples was conducted to evaluate how index misassignment caused false positives could affect the interpretation of microbial ecological roles and community assembly mechanisms.

Additional file 4: Figure S3. Venn diagrams showing the shared OTUs among distinct samples sequenced within the same batch of sequencing run on the Novaseq platform. The large number of shared OTUs among distinct samples (including two customized communities) were likely sample wise cross contaminations caused by index misassignment.

Additional file 6: Figure S5. Weighted (A) and unweighted (B) UniFrac distance-based clustering of the amplicon sequencing results revealed by DNBSEQ and NovaSeq sequencing platforms for samples from the three typical ecosystems.

Additional file 3: Figure S2. Comparison of shared fraction of OTUs by different sequencing platforms. UpSet graph showing the number of shared OTUs among the technical triplicates of DNBSEQ and NovaSeq sequencing platforms for customized mock community with four (A) or seven (B) microbes used in the current study. And heatmap showing the phylum rank relative abundances revealed by different sequencing platforms for the commercial mock (C) and customized mock communities with four (D) or seven (E) bacteria.

Additional file 8: Figure S7. Comparison of the results using unoise3 and DADA2 denoising algorithms. The accumulated OTU relative abundances in each phylum based on unoise3 and DADA2 were graphed as bar-chart side-by-side for all the mock communities and samples from three typical ecosystems.

DNA methylation is an important epigenetic regulator of gene transcription, and is involved in many diseases, which has been researched recently. In this study, we aimed to investigate DNA methylation and gene expression in preeclampsia placenta. Preeclampsia has been observed in patients with molar pregnancy where a fetus is absent, which demonstrates that the placenta is sufficient to cause this condition.DNA methylation profiles and mRNA expression profiles were compared between two groups, six preeclampsia placentas and six normal pregnancy placentas using microarrays.The number of promoters with altered DNA methylation was 1664. The number of mRNA identified as differentially expressed between the two groups of placenta samples were 1446. And the number of matched genes with a typical relationship between DNA methylation and gene expression was 42 hypomethylated DNA with increased mRNA expression and 19 hypermethylated DNA with decreased mRNA expression. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and GO analysis were constructed based on the correlation between the differentially expressed DNA methylation and mRNAs.Our study is the first study to determine the genome-wide DNA methylation patterns in preeclampsia placenta using microarrays. The results revealed that clusters of DNA methylation were aberrantly altered in preeclampsia placenta compared with controls, which indicated misregulation of DNA methylation.