This document summarizes key hormones involved in human reproduction. It describes how gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the pituitary gland. FSH stimulates follicle growth in the ovaries and estrogen production, while the LH surge causes ovulation. Estrogen and progesterone provide feedback signals to regulate FSH and LH levels over the menstrual cycle. During pregnancy, placental hormones like human chorionic gonadotropin (hCG) and placental hormones help maintain the corpus luteum and support fetal development by preparing the uterus and breasts.

1. REPRODUCTIVE ENDOCRINOLOGY

4. GnRH
 Hypothalamus
 Peptide hormone
 Stimulate the basophil cells in pituitory gland
 Stimulate release of FSH and LH
 Usually released in a pulsatile manner

5. FSH
 Gonadotrophic hormone
 Released from anterior pituitory
 Modulated by ovarian sex hormones
 Increases when circulating oestrogen,
progesterone and inhibin levels are low
 FSH cause stimulation of antral follicles to
grow
 As the follicles grow, oestrogen is secreted
causing negative feedback to reduce FSH

6. LH
 Gonadotrophic hormone
 Released from anterior pituitory
 Regulated by oestrogen level.
 High circulating oestrogen increases LH
production
 High oestrogen & low progesterone during
end of follicular phase causes a positive
feedback mechanism causing LH surge
 Stimulate ovulation and stimulate
resumption of meiosis of oocyte

7. Oestrogen
 Ovarian sex steroid hormone
 Produced from granulosa cells
 Low level of oestrogen has inhibitory effect
on LH production (-ve feedback) and high
levels of oestrogen increase the production of
LH (+ve feedback)
 FSH causes aromatisation of androgens to
convert to oestrogen

8. Progesterone
 Sex steroid produced from theca and granulosa
cells in ovary
 Produced by LH surge and adds a +ve feedback
on LH
 Ongoing LH secretion and continuing granulosa
cell activity of corpus luteum maintains
progesterone level
 It Stabilizes the endometrium for pregnancy
 In the absence of β hCG, corpus luteum regress
and progesterone secretion decreases
 Withdrawal progesterone causes shedding of
endometrium leading to menstruation

9. Placental hormones

12. Protein hormones from
placenta
 hCG (Human Chorionic Gonadotrophin)
 HPL (Human Placental Lactogen)
 PS β-1 G (Pregnancy Specific β-1
 Glycoprotein)

29. Functions of steroid hormone
in pregnancy
 Oestrogen causes hypertrophy & hyperplasia of
myometrium
 Progesteron + oestrogen stimulate growth of uterus
 Oestrogen causes hypertrophy and proliferation of
breast ducts
 Both are required for adaptation of maternal organs
in various stages of pregnancy

30. Cont…
 Oestrogen sensitizes myometrium to oxytocin &
prostaglandin
 Progesterone, hCG and decidual cortisol inhibitT
cell mediated tissue rejection and protect foetus
 Both preserve gonadal function

31. Relaxin
 Source is corpus leuteum, placenta & decidua
 Relaxes symphysis and sacroiliac joints during
pregnancy
 Helps in cervical ripening