Reproductive aging in women is primarily due to the gradual reduction in the number of eggs (oocytes) over time. Oocytes cannot be reproduced, and while some develop and are released during ovulation, many others diminish as they become non-viable follicles and eventually disappear. This natural decline continues until menopause, at which point fertility ends entirely. Before menopause, fertility declines mainly due to the increased presence of oocytes with abnormal chromosomes (aneuploidy), which affects their viability.

Preimplantation Genetic Testing (PGT) has been used in various forms over the last two decades. Preimplantation Genetic Testing PGT involves testing early embryos following in vitro fertilization, IVF, and has now become an accepted part of genetic testing. Nowadays, PGT serves as a resource for couples who have a family history of monogenic (single gene) disorders, wherein the fetus is at high risk of inheriting the condition.

The vaginal microbiome plays an important role in influencing pregnancy outcome. Dominance of the vaginal niche by Lactobacillus species has been widely reported to be associated with a healthy, full-term pregnancy, specifically Lactobacillus crispatus. In contrast, diverse microbial communities depleted of Lactobacillus species and enriched with bacteria associated with Bacterial Vaginosis; a clinical syndrome characterized by vaginal discharge odor and polymicrobial overgrowth, increases the risk of adverse pregnancy outcomes including miscarriage and preterm birth. Preterm birth represents a significant global health burden.