Background: The purpose of this narrative review is to describe the mechanisms that are responsible for the development of infertility and PCOS, with a focus on the role of obesity, insulin sensitivity and treatment with metformin and GLP-1s. Methods: The relevant publications were identified after systematic queries of the following sources: PubMed, Google Scholar, Web of Science, and publishers’ databases, complemented by a cross-check of the reference lists. We used a combination of the search terms “polycystic ovary syndrome”, “obesity” and “insulin resistance” with “metformin”, “exenatide”, “liraglutide”, “semaglutide”, “orlistat” and terms relevant to the topic of each paragraph (e.g., “pathophysiology”, “metabolism”, “infertility”, “treatment”). Results: All articles describing the mechanisms responsible for the development of infertility and PCOS, with a focus on the role of obesity, insulin sensitivity and treatment with metformin and GLP-1s, were considered for this review. Conclusions: The existing research on GLP-1 receptor agonists (GLP-1RAs) has not conclusively established a specific therapeutic use for these drugs. Additionally, the efficacy of the newer generation of GLP-1RAs, particularly in terms of dosage and duration of exposure, warrants more extensive research. Understanding the optimal dosing and treatment duration could significantly enhance the therapeutic use of GLP-1RAs in managing PCOS and its associated conditions.

Background: Intrahepatic cholestasis of pregnancy (ICP) is the most common pregnancy-related liver disease, usually presented in the third trimester with pruritus, elevated transaminase, and serum total bile acids. Evidence shows that it can be developed in the first trimester, more commonly after in vitro fertilization (IVF) procedures, with the presence of ovarian hyperstimulation syndrome (OHSS). Methods: A literature search was conducted in the PubMed/MEDLINE database of case reports/studies reporting early-onset ICP in spontaneous and IVF pregnancies published until July 2023. Results: Thirty articles on early-onset ICP were included in the review analysis, with 19 patients who developed ICP in spontaneous pregnancy and 15 patients who developed ICP in IVF pregnancies with or without OHSS. Cases of 1st and 2nd trimester ICP in terms of “early-onset” ICP were pooled to gather additional findings. Conclusions: Proper monitoring should be applied even before expected pregnancy and during IVF procedures in patients with known risk factors for OHSS and ICP development (patient and family history), with proper progesterone supplementation dosage and genetic testing in case of ICP recurrence.

A eutopic endometrium in endometriosis shows altered immune responses, including abnormalities of NK cells and expression of plasma cells, related to reproductive issues. This study investigated the counts of CD56-positive NK cells and CD138-positive plasma cells in the basal decidua of term placentas in singleton pregnancies after endometriosis-related infertility conceived by assisted reproductive technology (ART). This single-center, case-control study involved immunohistochemical analysis of CD56-positive NK cells and CD138-positive plasma cells in basal decidua using primary monoclonal mouse antibodies, followed by secondary antibodies using a standardized protocol. CD56 and CD138 immunohistochemically positive cells were reported as the total cell count for each studied antibody expressed per 1 mm² of basal decidua (Olympus BX46 and Olympus Image Analyzer). Placental samples containing basal decidua from 36 participants with endometriosis-related infertility who conceived by ART, 31 participants with male factor infertility who conceived by ART and 40 healthy controls were included. Endometriosis decidua showed the lowest median count of CD56-positive NK cells (11.5 / mm², p = 0.039) in BD compared to male factor group (25 / mm²) and healthy controls (24.5 / mm²). No differences were found for CD138-positive plasma cells counts between study groups. Basal decidua in pregnancies after endometriosis-related infertility showed reduced total count of CD56-positive NK cells, without differences in the CD138-positive plasma cell counts compared to control groups. Future studies should investigate how changes in NK cells throughout pregnancy affect the development of perinatal complications and placental pathologies in women with endometriosis, which could uncover potential diagnostic and therapeutic targets.