Contraception: Fertility can be controlled by a variety of hormonal and non- hormonal methods of contraception.

The idea

Fertility control prevents fertilisation or implantation. Hormonal methods use synthetic hormones to disrupt the cycle. Oral contraceptives inhibit FSH production so no eggs mature. Progestogen-only methods slowly release progesterone to inhibit egg maturation and release. Non-hormonal methods act physically or chemically: condoms block sperm. Intrauterine devices (IUDs) prevent embryo implantation or release a hormone. Spermicides kill or disable sperm. Sterilisation cuts or blocks the oviducts or sperm ducts. Abstinence involves abstaining from intercourse when an egg may be in the oviduct. Each method has different effectiveness, side effects and protection against sexually transmitted infections.

What earns the marks

• Hormonal contraceptives contain synthetic hormones, such as oral contraceptives that inhibit FSH production so that no eggs mature.
• An injection, implant or skin patch of slow release progesterone inhibits the maturation and release of eggs for a number of months or years.
• Barrier methods such as condoms and diaphragms stop sperm reaching an egg.
• Intrauterine devices (IUDs) prevent the implantation of an embryo or release a hormone.
• Spermicidal agents kill or disable sperm.
• Surgical sterilisation blocks the oviducts or sperm ducts, preventing sperm and egg from meeting.
• Abstinence involves abstaining from intercourse when an egg may be in the oviduct, so fertilisation cannot occur.
• Some methods, such as condoms, also reduce the risk of sexually transmitted infections, whereas hormonal methods do not.

Common mistakes and how to put them right

• Thinking the pill works by killing sperm.

  Put it right: Hormonal methods mainly prevent ovulation by inhibiting FSH.

• Confusing the oviduct with the uterus.

  Put it right: Fertilisation normally occurs in the oviduct, while the endometrium lining the uterus is where implantation occurs.

• Defining abstinence as never having intercourse.

  Put it right: In this context, it means abstaining from intercourse when an egg may be in the oviduct.

Exam tips

• Link each method to its mechanism: hormonal methods inhibit egg maturation and release, barrier methods block sperm, and surgical methods cut or block ducts.
• When comparing methods, refer to effectiveness, side effects and protection against sexually transmitted infections, not just convenience.