Controlling Fertility

• Pregnancy can happen if sperm reaches the ovulated egg. Contraception tries to stop this happening
• Hormones can be used to reduce fertility
• Oestrogen can be used to prevent the release of an egg - so it can be used as a method of contraception
• Using oestrogen as a contraceptive might seem strange (since naturally oestrogen helps stimulate the release of eggs). But is oestrogen is taken every day to keep the level of it perminently high, it inhibits the production of FSH, and after a while egg development and production stop and stay stopped
• Progesterone also reduces fertility, e.g. by stimulating the production of thick mucus which prevents any sperm getting through and reaching an egg
• The pill is an oral contraceptive containing oestrogen and progesterone (known as the combined oral contraceptive pill)
• The pill is over 99% effective at preventing pregnancy, but it can cause side effects like headaches and nausea and it doesn't protect against sexually transmitted diseases
• There is also a progesterone-only pill - it has fewer side effects than the pill, and is just as effective
• The contraceptive patch contains oestrogen and progesterone (the same as the combined pill). It's a small (5cm x 5cm) patch that's stuck to the skin. Each patch lasts one week
• The contraceptive implant is inserted under the skin of the arm. It releases a continuous amount of progesterone, which stops the ovaries releasing eggs, makes it hard for sperm to swim to the egg, and stops any fertilised egg implanting in the uterus. An implant can last for 3 years
• The contraceptive injection also contains progesterone. Each dose lasts 2 to 3 months
• An intrauterine device (IUD) is 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 - plastic IUDs that release progesterone and copper IUDs that prevent the sperm surviving in the uterus
• Barries stop egg and sperm meeting
• Non-hormonal forms of contraception are designed to stop the sperm from getting to the egg
• Condoms are worn over the penis during intercourse to prevent sperm from getting to the egg. 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
• A diaphragm is a shallow plastic cup that fits over the cervix (entrance to the uterus) to form a barrier. It has to be used with spermicide
• Spermicide can be used alone as a form of contraception, but it's not as effective (70-80%)
• Sterilisation - sterilisation involves cutting or tying the fallopian tubes (which connect the ovaries to the uterus) in a female, or the sperm duct (the tube between the testes and penis) in a male. This is a permanent procedure. However, there is a very small chance that the tubes can rejoin
• 'Natural methods' - pregnancy may be avoided by finding out when in the menstural cycle the woman is most fertile and avoiding sexual intercourse on those days. It's popular with people who think that hormonal and barrier methods are unnatural, but it's not very effective
• Abstinence - the only way to be completely sure that sperm and egg don't meet us to not have intercourse
• Scientific advances in understanding fertility have led to many infertile women being helped to have babies
• Hormones can be used to increase fertility
• Some women have levels of FSH (follicle-stimulating hormone) that are too low to cause their eggs to mature. This means that no eggs are released and the women can't get pregnant
• The hormones FSH and LH can be given to women in a fertility drug to stimulate ovulation
• Pros of the FSH and LH drug

  • It helps a lot of women to get pregnant when previously they couldn't
• Cons of the FSH and LH drug:

  • It doesn't always work - some women may have to do it many times, which can be expensive
  • Too many eggs could be stimulated, resulting in unexpected multiple pregnancies (e.g. twins)
• IVF can help couples to have children
• If a woman cannot get pregnant using medication, she may chose to try IVF (''in vitro fertilisation'')
• IVF 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. The fertilised eggs are then grown into embryos in a laboratory incubator
• 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. FSH and LH are given before egg collection to stimulate several eggs to mature (so more than one egg can be collected)
• Pros of IVF:

  • Fertility treatment can give an infertile couple a child
• Cons of IVF:

  • Multiple births can happen if more than one embryo grows into a baby - these are risky for the mother and babies (there's a higher risk of miscarriage...)
  • The success rate of IVF is low - the average success rate in the UK is about 26%. This makes the process incredibly stressful and often upsetting, especially if it ends in multiple failures
  • As well as being emotionally stressful, the process is also physically stressful for the woman
  • Some women have a strong reaction to the hormones - e.g. abdominal pain, vomiting...
• Advances 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. They're also used to remove single cells from the embryo for genetic testing (to check that it's healthy)
• More recently, the development of time-lapse imaging (using a microscope and 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. Because of this, some people think it's 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