A number of problems associated with the female reproductive system are ensued from the anomalies mainly in the hormonal cascade of hypo-thalamic-pituitary-thyroid-adrenogonadal ovarian pivot that ultimately leads to infertility [1, 2]. Following cancer and cardiovascular diseases, infertility has become the third most prevalent disease of the world and escorts a conspicuous physiological, economical, therapeutic and psychological stresss to sufferers and the whole society that cannot be underestimated [3]. Infertility is a medical condition which can be either primary i.e, when a couple fails to conceive after two years of regular and unprotected intercourse without the use of contraception [4-6] or it can be secondary in which a couple fails to conceive for the number of children they wanted to have [7]. Multiple statutory parameters are delimited for its cause i.e., age, weight, lifestyle and family history [1]. World Health Organization has been estimated that 12-14% of couples around the globe suffered from infertility with 40% due to the female partner, 30% due to the male infertility and another 30% may have involved mutual problem or undiagnosed [6].
Endocrine system with its glands and hormones is second most important regulatory system of the body after the nervous system [8]. Being the most prominent factors of fertility it is a crucial demand to assess the hormonal secretions of the endocrine glands. Gonadotropins with anti-mullerian hormone and thyroid hormones from anterior pituitary and presence primordial follicles principally influence the normal reproductive health [9]. Pituitary hormones, in particular, thyroid stimulating hormone (TSH), prolactin and gonadotropins act synergistically to trigger the growth of non-growing follicles [1].
Thyroid hormones have profound effect on the menstrual irregularity and lower fecundity. Therefore, thyroid relation with infertility always considered while treating infertile women [11]. Infertility with thyroid dysfunction is categorized as decreased sex hormone binding globulin (SHBG) activity, eventually lead to increased bounded fractions of testosterone and estradiol [7].
Gonadotropins are released from the anterior lobe of the pituitary, FSH and LH are the prominent stimulators to the Gonads via bloodstream. Follicular development is induced by the FSH in the ovaries. Specifically follicle stimulating hormones (FSH) is a major promoter for orchestrating follicular development and differentiation in the granulosa cells of preovulatory follicles [8]. Luteinizing hormone (LH) plays a key role in initiation of the ovulatory process of preovulatory follicles by activating multiple cellular signaling pathways [9]. Hormonal balance between estrogen, progesterone, FSH and LH is important to induce and promote fertility. LH stimulates the release of the ovum from the ovary and surge at around day 12 of menstrual cycle leads to ovulation within 48 hours. Elevated levels of FSH and LH indicate poor follicle development and consequently, anovulatory cycles and ovarian dysfunction, respectively [1]. Reduced levels of FSH and LH may indicate hyperprolactinaemia [5].
Autopsical analysis of the human ovaries revealed that Number of growing follicles decreases rapidly with the age of the female. To assess the ovarian reserves AMH and AFC are used as the main reproductive markers. Reproductive aging is a natural phenomenon which is related to the decrease in the quality and quantity of the ovarian follicular pool. Likewise, there is an exponential decrease in the number of follicles with the increasing age, which enter the growing phase which leads them towards antral developmental stages [31]. It is certain that delivery of the monthly ovulatory follicle declines with size of the antral follicle cohort which is due to a decrease primordial reserve. Transvaginal Ultrasonography is used to visualize the antral follicular count of the ovaries.
Anti-Mullerian hormone belongs to the superfamily of transforming growth factor-beta (TGF-β). It is a dimeric glycoprotein which is composed of two homodimers (N-terminal 55 KDa and C-terminal 12.5 KDa). AMH is produced by the preantral follicles in small amounts and by antral follicles in larger amounts. AMH is secreted from the granulosa layer. It has it inhibitory effects on Initial recruitment by acting on primordial follicle and on cyclic recruitment by having same effect on FSH sensitivity for follicles. From 36th week of gestation Granulosa cells of small growing follicles produce AMH and it is regulated until menopause where it has undetectable concentration. The levels of AMH in serum reflects the follicular pool in ovaries [32]. AMH has constant level of secretions throughout menstrual cycle, unlike FSH and LH that must be measured at early follicular phase [33]. AMH has a role in folliculogenesis and also influences the follicular atresia.
Possibly, impaired thyroid function may affect the ovarian function, and prove to be a diagnostic factor in the occurrence of secondary infertility. In the present study, the relationship between thyroid function and AMH levels evaluated by comparing them in two secondary infertile groups based on normal and overweight population. This study aims to determine any association between thyroid hormones and other related hormonal factors which govern the state of infertility under the impact of BMI.