Dados do Trabalho

Title

MISCARRIAGE IN ASSISTED REPRODUCTION - SYSTEMATIC REVIEW

Objective

To systematically evaluate in the literature the incidence and causes of spontaneous abortion in assisted reproduction.

Methods

This is an integrative review of articles published in the PubMed, VHL and SciELO databases in the last ten years, using the following descriptors: "Miscarriage" and "Assisted Reproduction". The inclusion criteria were articles written in Portuguese and English, with full text availability in electronic support. Paid studies, carried out on animals, duplicates and those that are not related to the theme were excluded.

Results

Three review articles were selected for analysis, according to the inclusion and exclusion criteria. In the first study, 2709 cycles of IVF treatment were included, in which four hundred and eleven ended in early pregnancy loss, and 2,298 had live births. The rate of miscarriages was 14.1% and the influence factors were female age, female BMI, type of cycle, thickness of the endometrium and tubal factor. Female patients aged 40 years or older had increased chances of early pregnancy loss compared to those under 35. Female patients with a BMI of 25 or more were more likely to have miscarriages than those in the normal BMI range. The relationship between obesity and the increased rate of gestational loss after IVF was related to metabolomic, epigenetic or mitochondrial disorders of oocytes and embryos, or to the abnormal endocrine, metabolic and inflammatory uterine environment induced by obesity, related to the lower rates of embryo implantation and the increased risk of miscarriage observed after embryo transfers. The chances of pregnancy loss after the transfer of frozen embryos were higher than after the transfer of fresh embryos. A thin endometrium on the day of embryo transfer increased the chances of embryonic death. The transfer of more than two embryos had lower chances of miscarriage compared to the transfer of a single embryo. In the second article, the focus was on the association between a gradual increase in abortion at in vitro fertilization and female age, in addition to oocyte quality and gestational loss. Regarding age, rates increase by more than 45% among women over 45 years of age, when compared to those under 34 years of age. Regarding the decline in oocyte quality, which reflects a high rate of miscarriage, oocyte aneuploidy was correlated as the most frequent cause. In addition, the risk of miscarriage was higher in women undergoing IVF with a female cause for infertility compared to male factor or unexplained infertility, among which having a higher incidence of secondary infertility, as it is possible that women with secondary subfertility had a previous miscarriage. Then, in the third study, the relationship between a previous induced abortion, whether medicated or surgical, and the results of in vitro fertilization was evaluated. A total of 1,532 cycles of IVF treatment were included; 454 patients had a history of induced abortion and 1,078 did not.The rate of miscarriage was significantly higher (17.6%) vs (9.8%) and the endometrium was significantly thinner among patients with a history of induced abortion compared to those without.

Conclusion

Thus, it is understood that abortion rates in assisted reproduction are significant and recurrent in specific cases, which should have a more attentive and careful look so that the procedures have positive results.

Keywords

Assisted Reproduction; Miscarriage; IVF.