Hormonal contraception

Hormonal contraceptives use hormones to reduce the chance of pregnancy. They can prevent an egg from maturing or being released from an ovary. The release of an egg is called ovulation.

Some oral contraceptive pills contain hormones that inhibit the production of follicle-stimulating hormone (FSH). FSH normally stimulates eggs to mature in the ovaries. When its production is inhibited, eggs do not mature.

Injections, implants and skin patches also deliver hormones, including progestogens. These hormones can inhibit egg maturation and ovulation.

Hormonal contraception: Use and duration

The methods differ in how they are used and how long they act:

• Pills must be taken regularly.
• Injections are renewed at intervals.
• Implants can act for years.
• Skin patches are replaced regularly.

Effectiveness depends partly on using the method correctly and renewing or replacing it on time. Hormonal contraceptives do not protect against sexually transmitted infections.

Barrier contraception

Barrier methods of contraception physically prevent sperm from reaching an egg. They place a barrier in the path sperm would otherwise take through the reproductive system.

A condom is worn over the penis. It collects semen and keeps it out of the vagina, preventing the sperm in the semen from travelling towards an egg. A diaphragm is placed inside the vagina over the cervix, the opening to the uterus. It obstructs sperm from entering the uterus.

Barrier methods must be used correctly during intercourse. Incorrect use or failure of the barrier can allow sperm through, reducing the method’s effectiveness at preventing pregnancy.

Condoms also reduce the risk of sexually transmitted infections (STIs) by limiting contact with infected body fluids. Diaphragms do not provide the same protection against STIs.

Intrauterine contraception

Intrauterine contraception uses a small device placed in the uterus to prevent pregnancy. There are two types: a non-hormonal copper device and a hormonal device.

Copper and hormonal devices

A copper device interferes with sperm, primarily preventing them from fertilising an egg. It may also prevent a fertilised egg from implanting in the uterine lining.

A hormonal intrauterine device releases a hormone called a progestogen. This thickens the mucus at the cervix, the opening to the uterus, making it harder for sperm to pass through and reach an egg. The hormone also thins the uterine lining.

Use of intrauterine contraception

An intrauterine device provides long-lasting contraception without requiring action during each act of intercourse. It must be fitted and removed by a trained health professional.

Neither type protects against sexually transmitted infections.

Spermicides

Spermicides are chemicals that kill or disable sperm. This reduces the chance that sperm will reach and fertilise an egg, helping to prevent pregnancy.

Spermicides may be used with a barrier method, which physically prevents sperm from reaching an egg. They must be used correctly to work effectively and are generally less reliable when used alone than many other contraceptive methods.

Spermicides do not protect against sexually transmitted infections.

Fertility-awareness contraception

Fertility-awareness contraception can involve avoiding vaginal intercourse on days when sperm could meet an egg. These days are called the fertile window.

The fertile window includes the time around ovulation, when an egg is released from an ovary and may be in an oviduct. It also includes days before ovulation because sperm can survive in the reproductive tract for several days. Sperm from intercourse before ovulation may therefore still be present when the egg is released.

Fertility awareness: effectiveness and protection

This approach does not require hormones or a device. Its effectiveness depends on identifying fertile days accurately and avoiding vaginal intercourse during them. Ovulation does not always occur at the same time, so predicting the fertile window is uncertain.

Fertility-awareness contraception does not protect against sexually transmitted infections during intercourse.

Surgical sterilisation

Sterilisation is a surgical method of contraception intended to be permanent. It prevents pregnancy by stopping sperm and egg from meeting.

Vasectomy

In a vasectomy, the sperm ducts are cut or sealed. This prevents sperm from entering the semen, so sperm cannot reach an egg during intercourse.

A vasectomy does not work immediately. Another method of contraception is needed until testing confirms that the semen no longer contains sperm.

Female sterilisation

In female sterilisation, the oviducts are cut or blocked. This prevents sperm from travelling along an oviduct to reach an egg.

Considering sterilisation

Sterilisation avoids the need to use contraception during each act of intercourse, but it is intended to be permanent. It does not protect against sexually transmitted infections.