Controlling Fertility

• Oestrogen can be used to prevent the release of an egg, so it can be used as a method of contraception
• If oestrogen is taken everyday to keep the level of it permanently high, it inhibits the production of FSH, and after a while egg development and production stop and stay stopped
• Progesterone reduces fertility, e.g. by stimulating the production of thick mucus which prevents any sperm getting through and reaching an egg
• The pill:

  • an oral contraceptive containing oestrogen and progesterone (known as the combined oral contraceptive pill)
  • it is over 99% effective at preventing pregnancy
  • it can cause side effects like headaches and nausea and doesn't protect against sexually transmitted diseases
  • there is also a progesterone-only pill, which has fewer side effects than the pill, and is just as effective
• Contraceptive patch:

  • contains oestrogen and progesterone
  • a small patch that's stuck to the skin
  • each patch lasts one week
• Contraceptive implant:

  • inserted under the skin of the arm
  • releases a continuous amount of progesterone, which stops the ovaries releasing eggs, making it hard for the sperm to swim to the egg, and stops any fertilised eggs implanting in the uterus
  • an implant can last for three years
• Contraceptive injection:

  • contains progesterone
  • Each dose lasts 2-3 months
• IUD (intrauterine device):

  • a T-shaped device that is inserted into the uterus to kill sperm and prevent implantation of a fertilised egg
  • there are 2 main types of IUD - plastic IUDs that release progesterone, and copper IUDs that prevent the sperm surviving in the uterus
• Non-hormonal forms of contraception are designed to stop the sperm reaching the egg
• Condoms:

  • worn over the penis during intercourse to prevent the sperm entering the vagina
  • there are also female condoms that are worn inside the vagina
  • condoms are the only form of contraception that will protect against sexually transmitted diseases
• Diaphragm:

  • a shallow plastic cup that fits over the cervix (the entrance to the uterus) to form a barrier
  • has to be used with a spermicide
• Spermicide

  a substance that disables or kills the sperm
• Spermicide can be used alone as a form of contraception, but it is not as effective (only about 70-80%)
• Sterilisation:

  • involves cutting or tying the fallopian tubes in a female, or the sperm duct in a male
  • this is a permanent procedure
  • there is a very small chance that the tubes can rejoin
• Natural methods:

  • finding out when in the menstrual cycle a woman is most fertile and avoiding sexual intercourse on those days
  • popular with people who think that hormonal and barrier methods are unnatural
  • not very effective
• Abstinence:

  • not having intercourse
  • the only way to be completely sure that sperm and egg don't meet
• Some women have levels of FSH that are too low to cause their eggs to mature, which means that no eggs are released and the women can't get pregnant
• The hormones FSH and LH can be given to women as a fertility drug to stimulate ovulation
• Positives of using hormones to increase fertility:

  • it helps a lot of women to get pregnant when they previously couldn't
• Negatives of using hormones to increase fertility:

  • it doesn't always work, so some women may have to do it many times, which could be expensive
  • too many eggs could be stimulated, resulting in unexpected multiple pregnancies (twins, triplets, etc.)
• IVF (in vitro fertilisation)

  involves collecting eggs from the woman's ovaries and fertilising them in a lab using the man's sperm
• IVF treatment can also involve a technique called intra-cytoplasmic sperm injection (ICSI), where the sperm is injected directly into an egg - it's useful if the man has a very low sperm count
• Process of IVF:

  1. the woman's eggs are fertilised by the man's sperm in a lab
  2. the fertilised eggs are then grown into embryos in a laboratory incubator
  3. once the embryos are tiny balls of cells, one or two of them are transferred to the woman's uterus to improve the chance of pregnancy
  4. FSH and LH are given before egg collection to stimulate several eggs to mature (so more than one egg can be collected)
• Positives of IVF:

  • fertility treatment can give an infertile couple a child
• Negatives of IVF:

  • multiple births can happen if more than one embryo grows into a baby, which is risky for the mother and babies
  • the success rate is low - the average success rate in the UK is about 26%. This makes the process very stressful and often upsetting, especially if it ends in multiple failures
  • the process is also physically stressful for the woman, as some women have a strong reaction to the hormones, e.g. abdominal pain, vomiting and dehydration
• Advantages in microscope techniques have helped to improve the techniques, and therefore the success rate, of IVF
• Specialised micro-tools have been developed to use on the eggs and sperm under the microscope
• Micro-tools are also used to remove single cells from the embryo for genetic testing to check that it is healthy
• The development of time-lapse imaging (using a microscope and a camera built into the incubator) means that the growth of the embryos can be continuously monitored to help identify those that are more likely to result in a successful pregnancy
• The process of IVF often results in unused embryos that are eventually destroyed and, because of this, some people think it is unethical because each embryo is a potential human life
• The genetic testing of embryos before implantation also raises ethical issues as some people think it could lead to the selection of preferred characteristics, such as gender or eye colour