Today's sexually liberated society is one that has been nurtured by forty years of the Pill. But there are many other contraceptive choices. Jennifer Paterson takes a look at the pros and cons.

This guide is designed as a guide to the advantages and disadvantages of various methods of preventing pregnancy and does not deal with the prevention of STDs.

Gynaecologist Douglas Keeping comments that no one contraceptive method is suitable for every individual. "It really depends on your lifestyle and what sort of relationship you are in at the time as to what method will suit you best."

There are six classes of contraceptive: hormonal methods, barriers, intrauterine devices (IUDs), spermicides, sterilisation, and natural methods.

Hormonal methods are used by women in the form of oral contraceptives - ie pills, implants, or injections. The hormones used are oestrogen and progestin. The former prevents the egg from maturing and the latter changes the lining of the uterus and cervical mucus such that they become infertile.

The Pill is taken at the same time on 21 consecutive days, with no pill taken for the ensuing 7 to complete the 28 day cycle.

The Pill reduces the risk of ovarian and uterine cancer, pelvic inflammatory disease, and ovarian cysts. In some cases it decreases pre-menstrual syndrome, acne, bleeding, anaemia, less rheumatoid arthritis symptoms, and breast tenderness. Because it is a cyclic treatment, periods are more regular. The Pill is suitable for women over age 40 and does not interfere with lovemaking. An oestrogen-free alternative, the 'minipill', can also be used while breast feeding.

The Pill's cyclic nature is a disadvantage as it must be taken every day. The Pill cannot be used by those with a history of breast cancer, blood clots (or risk of developing blood clots), liver disease, kidney disease, unexplained uterine bleeding, smokers over age 35, melanoma, and users of certain medications. Women with light periods, high blood pressure, diabetes, migraine headaches, depression, sickle cell disease and fibroids should not use the Pill.

Rare and serious side effects are blood clots, liver disease, high blood pressure, gall bladder disease, migraine headaches. Common side effects include nausea, breast tenderness, mid-cycle bleeding the first few months, weight gain, increased appetite, mood swings, depression, headaches, and skin problems.

Injections, like Depo-Provera do away with the daily dosage dilemma. Depo-Provera, a progestin injection, is a three-month treatment, contains both oestrogen and progestin and is a monthly treatment. It allows a return to fertility within a similar timeframe to the Pill but Depo-Provera may take from 6 to 24 months.

The injections may decrease menstrual cramps but as well as having the restrictions of the Pill have the added possible side effects of irregular periods, loss of libido, bloating/weight gain, headaches, depression, bone mineral loss, nervousness, skin rashes or spotty darkening of the skin, and increased body hair.

Dr Keeping notes that this method is not as popular as more the more traditional method of taking the pill "Any side effects the user experiences will take months to leave their system, daily dosage of the pill is a lot easier to monitor."

There are both male and female 'barriers'. The male condom is the most common, but the female diaphragm, sponge, cap, and condom are also available.

The disadvantages common to barriers are that they interfere with spontaneity and that some people are allergic to latex and/or spermicide. They are also single-use contraceptives that must be used every time. The most positive aspect of barriers is that they do not interfere with fertility.

There are also factors to consider for individual products as well: Diaphragms and cervical caps cannot be used by women with a history of abnormal pap smears, toxic shock syndrome. They must be kept in the vagina for at least eight hours after intercourse, and are prescription contraceptives that need to be fitted by a professional.

Diaphragms need to be re-fitted after a 5 kilogram weight loss or gain and after pregnancy and may result in an increase in urinary tract infections. Cervical caps may become dislodged, have limited sizes available, and need more frequent pap smears the first 1-2 years of use because it may cause changes in the cells of the cervix.

Some spermicides cause vaginal irritation.

Condoms may break and also are visually displeasing. The female condom is sometimes difficult to insert and reduces vaginal sensation.

IUDs, conversely, do not affect lovemaking. They are long-lasting contraceptives (the progesterone IUD lasts one year while the copper IUD lasts ten) but fertility returns once they are removed. They can also be used while breast-feeding.

Users must check for the string after every period as the IUD may be expelled unknowingly. Side effects can include cramps, backache, spotting, and heavy periods. IUD use may increase the risk of tubal pregnancy, pelvic inflammatory disease (PID), and infertility.

IUDs should not be used by women who have never had children or still want children; an allergy to copper (for the copper IUD); an artificial heart valve; a history of decreased immune problems; multiple sex partners; or a history of PID or tubal pregnancy.

Sterilisation is a procedure which, while possibly reversible, should be given serious consideration. The other thing to consider is that it also involves surgery. Dr Keeping notes that "A lot of couples may be under the false impression that sterilisation is 100 percent reversible, and that is not the case. The longer you leave it, in particular, the more likely it is to be irreversible."

Natural methods are popular because they are sanctioned by many religions. Generally withdrawal is likened to Russian roulette as many millions of sperm escape the penis before ejaculation. The rhythm method is discounted because everyone's cycle is different.

A more clinical method, involving calendars, temperature, and calculation -can be quite successful, but requires extensive instruction and dedication.

Natural methods can work if used properly - their shortcoming is the difficulty in perfecting them and the myriad of variables that can throw a spanner in the works.

The Bottom Line

When all things are considered, the factor most people look for must certainly be the success rate. In 1997, the US Food and Drug Administration released a comprehensive table detailing the probability of pregnancy.

There are many factors in choosing which contraceptive is right for you, but obviously you need to pick one that will work.