Background/Objectives: There are indications that the microbial composition of the maternal mucosal surfaces is associated with adverse events during pregnancy. The aim of this review is to investigate the link between vaginal microbiome alterations and gestational complication risk. Methods: This comprehensive literature review was performed using Medline and Scopus databases. The following search algorithm was used, “Pregnancy Complications” [Mesh] AND (Vagin*), and after the literature screening, 44 studies were included in the final review. Results: The studies that were included investigated the association between vaginal microbial composition and preterm birth, miscarriage, preeclampsia, ectopic pregnancy, gestational diabetes mellitus, chorioamnionitis, and preterm premature rupture of membranes. In most of the studies, it was well established that increased microbial diversity is associated with these conditions. Also, the depletion of Lactobacillus species is linked to most of the gestational complications, while the increased relative abundance and especially Lactobacillus crispatus may exert a protective effect in favor of the pregnant woman. Several pathogenic taxa including Gardnerella, Prevotella, Sneathia, Bacterial Vaginosis-Associated Bacteria-2, Atopobium, and Megasphera seem to be correlated to higher maternal morbidity. Conclusions: Vaginal microbiome aberrations seem to have an association with pregnancy-related adverse events, but more high-quality homogenous studies are necessary to reliably verify this link.

Background and Objectives: Caesarean scar pregnancy (CSP) is a rare form of ectopic pregnancy in which the early pregnancy implants at the site of the uterine scar. Methotrexate (MTX) in lower doses can be used to treat CSPs. However, MTX administration is associated with a spectrum of side effects that include hematological toxicities. This case report presents a CSP treated with an intragestational injection of MTX and subsequently developed pancytopenia. Materials and Methods: A 23-year-old woman at six weeks and six days of pregnancy was referred as a potential case of CSP. After establishing the diagnosis, she was treated with a transvaginal ultrasound-guided intragestational administration of 80 mg MTX (adjusted to 50 mg/m² body surface area) under sedation. Results: On day four after the MTX injection, she developed oral ulcers, fever, and pruritic phlyctenular maculopapular rash. Subsequently, the patient developed febrile neutropenia and was admitted to the Intensive Care Unit. On day six, a subsequent exacerbation of the rash was observed with the formation of blisters and purplish spots with concurrent odynophagia and sialorrhea. Ultimately, the patient developed pancytopenia due to bone marrow suppression. Fifteen days after MTX administration, the patient recovered and was discharged from the hospital hemodynamically stable, afebrile, with dropping β-hcg levels, and in good clinical condition. Conclusions: Although methotrexate administration is the preferred option for the treatment of cesarean scar pregnancies, clinicians should be aware of the fact that its use entails potential risks, even when it is used locally. To our knowledge, this case is the first description of pancytopenia due to bone marrow suppression following a single low dose of intragestational methotrexate injection.