The health risks associated with transferring embryos classified as mosaic by preimplantation genetic testing for aneuploidies (PGT-A) are currently unknown. Such embryos produce PGT-A results indicating the presence of both euploid and aneuploid cells and have historically been deselected from transfer and grouped with uniformly aneuploid embryos as ‘abnormal’. In recent years, numerous groups have reported the intentional transfer of mosaic embryos in the absence of uniformly euploid embryos, largely observing births of seemingly healthy babies. However, it remains to be understood whether the embryonic mosaicism invariably becomes resolved during the ensuing pregnancy, or whether the placenta and/or fetal tissues retain aneuploid cells, and if so to what potential clinical effect. Here, we report two cases of mosaicism persisting from the embryonic stage to the established pregnancy. Case 1 involved an embryonic low-level segmental mosaic loss in Chromosome (Chr) 1, which was confirmed in amniocentesis as well as in brain tissue of the products of conception. This pregnancy was terminated due to the chromosomal pathologies associated with 1p36 deletion syndrome, such as severe intellectual disability. Case 2 involved a low-level mosaic Chr 21 trisomy, which was confirmed with chorionic villus sampling and amniocentesis. The ensuing pregnancy was terminated after ultrasound identification of severe abnormalities in the placenta and fetus. Together, these two cases should be taken into account for risk-benefit assessments of prospective mosaic embryo transfers.

Research question: Is there any difference in clinical outcomes between the progesterone-modified fi ed natural cycle (P4mNC) and hormone replacement therapy (HRT) endometrial preparation protocols after single euploid blastocyst frozen embryo transfer (FET) cycles? Design: A retrospective cohort study was performed at a single, private, high-volume fertility centre. Patients who underwent single euploid blastocyst FET between January 2017 and December 2019 were included. A total of 1933 FET cycles were reviewed, and 723 FET cycles from 548 patients met the inclusion criteria. Two groups were compared according to endometrial preparation: 327 P4mNC-FET and 396 HRT-FET cycles. The primary outcome was the live birth rate. The secondary outcomes included the clinical pregnancy rate and the miscarriage rate. Results: There were no differences in the clinical pregnancy rate (50.2% versus 47.0%, P = 0.688), miscarriage rate (9.8% versus 14.5%, P = 0.115) and live birth rate (45.0% versus 39.6%, P = 0.331) between the P4mNC-FET and HRT-FET groups after covariate adjustments. Conclusions: There were no differences in the clinical outcomes between the P4mNC-FET and HRT-FET cycles. These results indicate that P4mNC-FET cycles produce clinical outcomes comparable to those of more traditional HRT-FET while allowing greater fl exibility in the timing of embryo transfer.

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age. Patients with PCOS present with several endometrial abnormalities possibly explaining some of the adverse endometrium-related outcomes in these women. PCOS is inconsistently associated adverse pregnancy outcomes and an increased risk of endometrial cancer. The purpose of this review is to systematize the available data on endometrial dysfunction associated with PCOS.

The Aim of the study was to assess modern considerations about the role of aromatase P450 enzyme in female reproductive system and the effect of its activity on the protocols of in vitro fertilization (IVF). Materials: foreign and Russian literature data from 1978 to 2016. Methods: review and synthesis of publications has been performed. Conclusions: Ovarian aromatase is the key steroidogenesis enzyme of the female reproductive system. Its activity depends on many factors, both of intraovarian and extragonadal origin. The ovarian follicular response and oocyte quality in IVF may depend on aromatase activity. (For citation: Yakovlev PP. Aromatase P450 activity in the natural menstrual cycle and during controlled ovarian stimulation. Journal of Obstetrics and Women’s Diseases. 2017;66(5):46-55. doi: 10.17816/JOWD66546-55).