2.3

• Fertile periods

  When a male is capable of fathering a child and a female is capable of conceiving and becoming pregnant
• Cyclical fertility

  Females show cyclical fertility leading to a fertile period. Women are only fertile a few days during each menstrual cycle.
• Continuous fertility

  Males show continuous fertility. Men continually produce sperm in their testes from puberty onwards.
• Identification of the fertile period

  1. Temperature rise of 0.5°C after ovulation

  2. Cervical mucus becomes thin and watery
• Infertility is when a couple are unable to conceive
• Causes of infertility

  • Failure to ovulate due to hormone problems
  • Low sperm count
  • High number of abnormal sperm
  • Blockage of the oviducts
• Stimulating ovulation

  1. Drugs that mimic the action of FSH and LH

  2. Drugs that interfere with the normal negative feedback effect of oestrogen on FSH secretion
• Artificial insemination (AI)

  1. Several samples of semen are collected over a period of time

  2. Sperm/semen is then inserted into the female reproductive tract by a syringe
• Intra-cytoplasmic sperm injection (ICSI)

  The head of the sperm is drawn into a needle and injected directly into the egg to achieve fertilisation
• In vitro fertilisation (IVF)

  1. Eggs are removed surgically from ovaries after hormone stimulation

  2. The eggs are mixed with sperm in a culture dish or fertilised by intra-cytoplasmic sperm injection (ICSI)

  3. The fertilised eggs (zygotes) are incubated until they have formed at least eight cells and are then transferred to the uterus for implantation
• Pre-implantation genetic diagnosis (PGD)

  Used in conjunction with IVF to identify single gene disorders and chromosomal abnormalities
• IVF can be used when infertility is caused by blockage of oviducts, which may have resulted from infection such as pelvic inflammatory disease (PID) or the STI chlamydia
• Physical methods used to prevent pregnancy

  • Condom
  • Diaphragm
  • Cervical cap
  • Intra-Uterine Device (IUD)
  • Vasectomy
  • Tubal ligation
• Oral contraceptive pill

  Contains a combination of synthetic oestrogen and progesterone that mimics negative feedback preventing the release of FSH and LH from the pituitary gland and hence suppressing ovulation
• Progesterone-only pill (mini-pill)

  Causes thickening of cervical mucus (preventing entry of sperm)
• Morning-after pills

  Prevents ovulation or implantation