Testosterone plays an important but often underappreciated role in women’s health. Although it is typically regarded as a “male” hormone, women also produce testosterone in smaller amounts—mainly in the ovaries, adrenal glands, and peripheral tissues. It functions as both an androgen and a precursor for estrogen synthesis, influencing a wide range of physiological systems.

In many species, female body odors reflect their reproductive status, and odors around the time of ovulation attract males, resulting in behavioral and/or physiological changes. In humans, several studies have suggested that female body odor signals periods of high fertility. For instance, vaginal secretions collected during the preovulatory and ovulatory phases are rated as more pleasant than those from the menstrual, early luteal, or late luteal phases. 

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.

In the journey of assisted reproductive technology (ART), in-vitro fertilization (IVF) has emerged as a transformative solution for individuals and couples striving to achieve parenthood. Among the various techniques in IVF, Frozen Embryo Transfer (FET) has gained remarkable prominence. Frozen Embryo Transfer, FET involves the cryopreservation of embryos and their subsequent thawing and transfer during a later menstrual cycle. Over the years, FET has demonstrated significant advantages, particularly in yielding higher implantation and pregnancy rates as compared to fresh embryo transfers. This article explores how FET has evolved, the scientific rationale behind its success, and its implications for reproductive medicine.