Menstruation + Fertility

• Menstrual cycle


  The cycle in women (typically lasting 28 days) that involves: Shedding of uterus lining (menstruation), Repair of uterus lining, Release of an egg (ovulation), Maintenance of uterus lining
• Stages of the menstrual cycle


  1. Days 1-4: if fertilisation and implantation do not occur the uterus lining sheds and the egg is expelled with it (menstruation)

  2. Days 4-14: uterus lining thickens and blood vessels grow in preparation for the implantation of an egg

  3. Day 14: egg released from a follicle into the oviduct (ovulation)

  4. Days 14-28: uterus lining maintained so implantation can occur
• Hormones that control the menstrual cycle


  • Follicle stimulating hormone (FSH)
  • Oestrogen
  • Luteinising hormone (LH)
  • Progesterone
• Role of FSH


  Secreted by the pituitary gland, Transported in the bloodstream to the ovaries, Triggers the development of a follicle in the ovaries which releases oestrogen
• Role of oestrogen


  Secreted by the ovaries, Repairs and thickens the uterus lining, Inhibits secretion of FSH from the pituitary gland, Stimulates secretion of LH from the pituitary gland
• Role of LH


  Secreted by the pituitary gland, Transported in the bloodstream to the ovaries, Surge in LH triggers ovulation, Stimulates follicle remains to develop into a corpus luteum which then secretes progesterone
• Corpus luteum


  Temporary endocrine structure, Mass of cells that releases progesterone, Degenerates after a few days
• Role of progesterone


  Secreted by the corpus luteum, Stimulates the growth of blood vessels in the uterus lining (in preparation for implantation), Inhibits the release of FSH and LH, If no implantation occurs, progesterone levels decrease and the uterus lining sheds. FSH increases and the cycle starts again.
• If fertilisation and implantation occur, the placenta produces progesterone so levels remain high. This prevents further ovulation and maintains the uterus lining.
• Contraceptives


  A method or device utilised to prevent pregnancy
• Hormones that can be taken to prevent pregnancy


  • Progesterone taken on its own
  • Progesterone combined with oestrogen
• How progesterone prevents pregnancy


  1. Sperm find it more difficult to enter the uterus as the cervical mucus is thickened

  2. Thins the uterine lining, reducing the likelihood of egg implantation

  3. Prevents ovulation in some women (but not all)
• How oestrogen prevents pregnancy


  Oestrogen inhibits FSH, preventing ovulation
• How progesterone can be administered as a contraceptive


  1. Mini-pill taken daily

  2. Injection
• How progesterone and oestrogen can be administered as a contraceptive


  1. Combined pill (taken continuously for 21 days then paused for 7 days)

  2. Skin patch (worn continuously for 3 weeks then without for 1 week)
• Benefits of hormonal contraceptive methods


  • 99% effective when used properly
  • Generally longer lasting than non-hormonal methods
  • Used to treat other conditions e.g. painful/heavy periods
• Risks of hormonal contraceptive methods


  • Side effects e.g. mood changes, acne, bloating
  • Do not protect against STIs
  • May involve uncomfortable medical procedures
  • Not effective if used incorrectly
• Barrier methods of contraception


  Prevent the sperm and egg meeting e.g. condoms, diaphragms (fit over cervix)
• Benefits of barrier methods of contraception


  • Condoms are simple and quick to use
  • Condoms prevent the spread of STIs
  • No side effects
• Risk of barrier methods of contraception


  Less effective than hormonal methods e.g. condom may split whilst in use
• Methods used to treat infertility (involving hormones)


  • Clomifene therapy
  • IVF
• Role of hormones in IVF


  1. FSH and LH given to a woman to stimulate egg production and ovulation

  2. Eggs retrieved from the woman's ovaries and fertilised in vitro

  3. Resultant embryo transferred to the woman's uterus
• Clomifene therapy


  Prescription of clomifene drug to women who do not ovulate regularly, Stimulates secretion of more FSH and LH which triggers egg production and ovulation
• Menstrual cycle


  The cycle in women (typically lasting 28 days) that involves: Shedding of uterus lining (menstruation), Repair of uterus lining, Release of an egg (ovulation), Maintenance of uterus lining
• Stages of the menstrual cycle


  1. Days 1-4: if fertilisation and implantation do not occur the uterus lining sheds and the egg is expelled with it (menstruation)

  2. Days 4-14: uterus lining thickens and blood vessels grow in preparation for the implantation of an egg

  3. Day 14: egg released from a follicle into the oviduct (ovulation)

  4. Days 14-28: uterus lining maintained so implantation can occur
• Hormones that control the menstrual cycle


  • Follicle stimulating hormone (FSH)
  • Oestrogen
  • Luteinising hormone (LH)
  • Progesterone
• Role of FSH


  Secreted by the pituitary gland, Transported in the bloodstream to the ovaries, Triggers the development of a follicle in the ovaries which releases oestrogen
• Role of oestrogen


  Secreted by the ovaries, Repairs and thickens the uterus lining, Inhibits secretion of FSH from the pituitary gland, Stimulates secretion of LH from the pituitary gland
• Role of LH


  Secreted by the pituitary gland, Transported in the bloodstream to the ovaries, Surge in LH triggers ovulation, Stimulates follicle remains to develop into a corpus luteum which then secretes progesterone
• Corpus luteum


  Temporary endocrine structure, Mass of cells that releases progesterone, Degenerates after a few days
• Role of progesterone


  Secreted by the corpus luteum, Stimulates the growth of blood vessels in the uterus lining (in preparation for implantation), Inhibits the release of FSH and LH, If no implantation occurs, progesterone levels decrease and the uterus lining sheds. FSH increases and the cycle starts again.
• If fertilisation and implantation occur, the placenta produces progesterone so levels remain high. This prevents further ovulation and maintains the uterus lining.
• Contraceptives


  A method or device utilised to prevent pregnancy
• Hormones that can be taken to prevent pregnancy


  • Progesterone taken on its own
  • Progesterone combined with oestrogen
• How progesterone prevents pregnancy


  1. Sperm find it more difficult to enter the uterus as the cervical mucus is thickened

  2. Thins the uterine lining, reducing the likelihood of egg implantation

  3. Prevents ovulation in some women (but not all)