Although circulating microRNAs (miRNAs) in maternal blood may play an important role in regulation of pregnancy progression and serve as non-invasive biomarkers for different gestation complications, little is known about their profile in blood during normally developing pregnancy. In this study we evaluated the miRNA profiles in paired plasma and serum samples from pregnant women without health or gestational abnormalities at three time points using high-throughput sequencing technology. Sequencing revealed that the percentage of miRNA reads in plasma and serum decreased by a third compared to first and second trimesters. We found two miRNAs in plasma (hsa-miR-7853-5p and hsa-miR-200c-3p) and 10 miRNAs in serum (hsa-miR-203a-5p, hsa-miR-495-3p, hsa-miR-4435, hsa-miR-340-5p, hsa-miR-4417, hsa-miR-1266-5p, hsa-miR-4494, hsa-miR-134-3p, hsa-miR-5008-5p, and hsa-miR-6756-5p), that exhibit level changes during pregnancy (p-value adjusted < 0.05). In addition, we observed differences for 36 miRNAs between plasma and serum (p-value adjusted < 0.05), which should be taken into consideration when comparing the results between studies performed using different biosample types. The results were verified by analysis of three miRNAs using qRT-PCR (p < 0.05). The present study confirms that the circulating miRNA profile in blood changes during gestation. Our results set the basis for further investigation of molecular mechanisms, involved in regulation of pregnancy, and the search for biomarkers of gestation abnormalities.

In recent years evidence has been accumulated showing that miRNAs can act as potential biomarkers or targets for therapy of preterm birth, one of the most important problems in modern obstetrics. We have performed a prospective study of the miRNA profile in the plasma during the first and second trimesters in pregnant women with high risk of preterm birth (n = 13 cases and n = 11 controls). For the study group plasma blood samples at 9–13 weeks before diagnosis and at 22–24 weeks after start of therapy were selected. Using high-throughput sequencing technology we detected differences in the levels of 15 miRNAs (3 upregulated—hsa-miR-122-5p, hsa-miR-34a-5p, hsa-miR-34c-5p; 12 downregulated—hsa-miR-487b-3p, hsa-miR-493-3p, hsa-miR-432-5p, hsa-miR-323b-3p, hsa-miR-369-3p, hsa-miR-134-5p, hsa-miR-431-5p, hsa-miR-485-5p, hsa-miR-382-5p, hsa-miR-369-5p, hsa-miR-485-3p, hsa-miR-127-3p) (log2(FC) ≥ 1.5; FDR ≤ 0.05) during the first trimester compared with the control (non-high-risk of preterm birth pregnant women). All downregulated miRNAs in the first trimester from the placenta-specific C14MC cluster. During the second trimester no differentially expressed miRNAs were found. Our results suggest that the miRNA profile in plasma during early pregnancy may predict a high risk of preterm birth, which is important in preventing gestational problems as early as possible.

Complications endangering mother or fetus affect around one in seven pregnant women. Investigation of the genetic susceptibility to such diseases is of high importance for better understanding of the disease biology as well as for prediction of individual risk. In this study, we collected and analyzed GWAS summary statistics from the FinnGen cohort and UK Biobank for 24 pregnancy complications. In FinnGen, we identified 11 loci associated with pregnancy hypertension, excessive vomiting, and gestational diabetes. When UK Biobank and FinnGen data were combined, we discovered six loci reaching genome-wide significance in the meta-analysis. These include rs35954793 in FGF5 (p=6.1×10−9), rs10882398 in PLCE1 (p=8.9×10−9), and rs167479 in RGL3 (p=5.2×10−9) for pregnancy hypertension, rs10830963 in MTNR1B (p=4.5×10−41) and rs36090025 in TCF7L2 (p=3.4×10−15) for gestational diabetes, and rs2963457 in the EBF1 locus (p=6.5×10−9) for preterm birth. In addition to the identified genome-wide associations, we also replicated 14 out of 40 previously reported GWAS markers for pregnancy complications, including four more preeclampsia-related variants. Finally, annotation of the GWAS results identified a causal relationship between gene expression in the cervix and gestational hypertension, as well as both known and previously uncharacterized genetic correlations between pregnancy complications and other traits. These results suggest new prospects for research into the etiology and pathogenesis of pregnancy complications, as well as early risk prediction for these disorders.

For today, twins make up about 1.5% of the population of our planet. It is more than one hundred million people, which in number corresponds to the population of two Frances. The number of twins born relative to the total number of newborns in different countries and on different continents is different, but the overall trend is that it continues to grow. In recent years, the percentage of multiple pregnancy has increased almost 2.5 times, which is associated with the widespread use of assisted reproductive technologies.At the same time, pregnancy in multiple births is an extremely important problem in modern obstetrics, as it is accompanied by a high level of complications for both the mother and the fetuses. Multiple pregnancy contributes significantly to the formation of adverse perinatal outcomes, which is primarily due to the high rate of preterm birth. Premature twins are at high risk of neurological and neuropsychiatric disorders, respiratory distress, endocrine and metabolic disorders, which subsequently become the cause of disability and social maladaptation of children. In this regard, the reduction in the number of premature births is today a priority task, the solution of which is possible only through timely and correct forecasting. The multifactority of pathogenic mechanisms determines the necessity of diagnostic search strategies that can identify markers of various pathogenetic ways of preterm birth. (For citation: Kosyakova OV, Bespalova ОN. Challenges and prospects of preterm birth prediction in multiple pregnancies. Journal of Obstetrics and Women’s Diseases. 2018;67(4):48-59. doi: 10.17816/JOWD67448-59).

Premature birth is one of the most important problems of modern obstetrics because it is a leading cause of childhood morbidity and mortality in all countries. Annually, > 1 million premature newborns worldwide die from various types of complications, and most of the survivors become disabled. Moreover, according to WHO analysis, most of these children can be saved by developing measures for the early identification of preterm births, which will provide additional time for effective intervention. Currently, available diagnostic methods do not adequately assess the risks of premature delivery owing to the low predictive value of the methods. This makes it necessary to search for predictors of preterm labor that can improve the accuracy of diagnostic techniques. The desired predictors should have a pathogenetic basis, and most importantly, they must contribute to the early detection of life-threatening premature births. The hormone relaxin could be considered to be a promising marker of premature birth because its role in the pathogenesis of premature birth is unquestionable, and the evaluation of its levels is possible during the early stages of pregnancy.