Controlling Fertility

• Pregnancy

  When sperm reaches the ovulated egg
• Contraception


  Tries to stop pregnancy from happening
• Hormones


  Can be used to reduce fertility
• Oestrogen used as contraception


  1. Taken every day to keep level permanently high

  2. Inhibits release of egg

  3. Egg development and production stop
• Progesterone


  Reduces fertility by stimulating production of thick mucus which prevents sperm reaching egg
• Combined oral contraceptive pill


  Contains oestrogen and progesterone
• Combined oral contraceptive pill

  • Over 99% effective at preventing pregnancy
  • Can cause side effects like headaches and nausea
  • Doesn't protect against sexually transmitted diseases
• Progesterone-only pill


  Has fewer side effects than combined pill, just as effective
• Other contraceptives containing hormones

  • Contraceptive patch (oestrogen and progesterone)
  • Contraceptive implant (progesterone)
  • Contraceptive injection (progesterone)
  • Intrauterine device (progesterone or copper)
• Contraceptive implant


  • Releases continuous amount of progesterone
  • Stops ovaries releasing eggs
  • Makes it hard for sperm to swim to egg
  • Stops fertilised egg implanting in uterus
  • Lasts for 3 years
• Intrauterine device (IUD)


  • T-shaped device inserted into uterus
  • Kills sperm and prevents implantation of fertilised egg
  • Plastic IUDs release progesterone, copper IUDs prevent sperm surviving
• Barriers


  Designed to stop egg and sperm meeting
• Barrier contraceptives


  • Condoms
  • Female condoms
  • Diaphragm
  • Spermicide
• Condoms


  • Worn on penis during intercourse to prevent sperm entering vagina
  • Only contraceptive that protects against sexually transmitted diseases
• Diaphragm


  • Shallow plastic cup that fits over cervix to block entrance to uterus
• Spermicide


  Substance that disables or kills sperm, used as a barrier contraceptive
• Sterilisation


  Cutting or tying fallopian tubes (female) or vas deferens (male) to prevent pregnancy
• Sterilisation


  • Permanent procedure but there is a small chance tubes can rejoin
• Natural methods


  Avoiding sexual intercourse on fertile days of menstrual cycle
• Natural methods


  • Not very effective at preventing pregnancy
• Abstinence


  The only way to be completely sure sperm and egg don't meet
• FSH (follicle-stimulating hormone)


  Hormone that can be given as fertility drug to stimulate ovulation in women with low levels
• LH (luteinizing hormone)


  Hormone that can be given as fertility drug to stimulate ovulation in women with low levels
• Using hormones to increase fertility

  • Helps a lot of women get pregnant when previously they couldn't
  • Doesn't always work, may need to do it many times
  • Can result in unexpected multiple pregnancies
• IVF (in vitro fertilisation)


  Process of collecting eggs from woman's ovaries, fertilising them in a lab using man's sperm, and transferring embryos to woman's uterus
• IVF


  • Gives infertile couples a chance to have a child
  • Multiple births are common and risky
  • Success rate is low, around 26% in UK
  • Physically and emotionally stressful for woman
• Advances in IVF

  • Improved microscope techniques
  • Specialised micro-tools for eggs and sperm
  • Time-lapse imaging to monitor embryo growth
• Some people think IVF is unethical because it results in unused embryos that are eventually destroyed
• Some people think genetic testing of embryos before implantation raises ethical issues as it could lead to selection of preferred characteristics