An interplay of Progesterone, Leukemia Inhibitor Factor and Interleukin-6 in the window of implantation; Impact on fertility

•Higher Progesterone levels increased the LIF levels in the fertile females during the window of implantation, supporting their role as implantation biomarkers.•The decreased LH/FSH ratio may be responsible for impaired secretion of Progesterone leading to reduced secretion of receptivity biomarker LIF in infertile women with PCOs and endometriosis.•A significant positive correlation was observed between LH and IL6, LIF, Progesterone, and Estradiol in fertile women, which helps determine the impact of these reproductive hormones and cytokines on fertility.•LIF showed a significant and positive correlation with IL6, Progesterone, Estradiol, and LH in fertile women, further establishing the impact of these reproductive hormones and cytokines on fertility.•The significantly low levels of IL6 in the unexplained infertile group elucidate the role of this cytokine in association with decreased Progesterone and LIF synthesis within this group. The process of implantation is crucial for the initiation of conception and hence fertility. In addition to a number of factors, it is regulated by a cross talk of gonadotrophins [Luteinizing Hormone (LH), Follicle Stimulatory Hormone (FSH)], ovarian steroids [Estrogen (Et), Progesterone (Pt)] and cytokines [Leukemia inhibitory factor (LIF) and Interleukin 6 (IL6)]. These biomarkers are chief players of implantation. We aimed to explore the role of gonadotrophins (LH, FSH, LH/FSH ratio), ovarian steroids (Et, Pt) and cytokines (LIF, IL6) in the implantation process. This aim was achieved by comparing these hormones and cytokines in the fertile and infertile groups [Polycystic ovaries (PCOs), endometriosis, unexplained infertility (Uex-IF)] and finding their association in all study groups. A case control study conducted from October 2020-March 2023. A total of 135 infertile women (with PCOs, Uex-IF, and endometriosis) and 177 fertile women (matched for age and BMI) were selected. Levels of ‘Et’, ‘Pt’, ‘LIF’ and, ‘IL6′ were estimated using Enzyme Linked Immunosorbent Assay (ELISA). LH and FSH values were obtained from hospital desk records. The Independent Student'st-test was used to compare fertile and infertile groups. One-way ANOVA test was used to compare more than two groups, and Pearson’s chi-square (χ2) test was employed to compare percentages of variables. Pearson correlation analysis was performed to assess the associations and correlations. A p value