Resultados perinatais após transferência de embriões criopreservados

Abstract

Over the last few decades, the use of assisted reproduction techniques (ART) has increased considerably in the world. The use of vitrification (freezing) of gametes and embryos allowed for better planning of treatments, and greater possibilities for couples. However, the interference of both the medications used in ART and the freezing of human cells are still under study. In this study, the objective was to evaluate the maternal and immediate neonatal outcomes of patients who became pregnant from the transfer of thawed embryos. For this purpose, a retrospective cohort which compared three different types of treatment for infertility was performed. Data refers to a period from 2013 to 2020 and were collected from electronic medical records. A total of 933 clinical pregnancies that evolved with single fetus were included. Of these, 708 evolved to live births, and were divided into three groups. Group 1, thawed embryo transfer (FET) (n=89), Group 2, fresh embryo transfer (IVF-ET) (n=497) and Group 3, ovulation induction (OI) (n=122). The variables related to maternal and neonatal outcomes were compared between groups and were expressed as mean ± SD or n (%). ANOVA test, Tukey's test and Chi-square test were applied, considering p<0.05. When comparing the three groups, no differences were found in relation to maternal outcomes. Regarding neonatal outcomes. Regarding neonatal outcomes, 4.3% of small for gestational age (SGA) newborns were observed in the FET group, 15.3% in the IVF-ET group and 7.5% in the IO group, p=0.011. Likewise, the mean weight (g) at birth was higher in the FET group (3332.2±481.3) compared to the fresh (3106.2±579.4) and IO (3195.9±560, 4), p=0.001. It was concluded that different treatments for infertility may be associated with unfavorable neonatal outcomes. The presence of more SGA neonates in the IVF-ET group may be related to the hormonal influence in an assisted reproduction cycle, with supraphysiological estrogen levels, and possibly harmful to the endometrium, culminating in an insufficient placental vascular adaptation. On the other hand, embryonic prior freezing may be related to cellular changes that are associated with fetuses with greater intrauterine growth.