How safe is the 'pill'?

The oral contraceptive pill (also simply known as the 'pill') was introduced to Australian women 50 years ago. And, without sounding too dramatic here, it's probably fair to say that this half-century milestone was a critical factor in ensuring our sexual and reproductive freedom. But what do we really understand about the machinations of how the 'pill' works?

When used properly, the 'pill' is an effective form of contraception. However, it is not useful in preventing the transmission of STDs such as Chlamydia and HIV/AIDS.

In Australia, there are two types of the 'pill': the combined pill and the progesterone-only pill (also called the mini-pill).

The combined pill
The combined pill contains oestrogen and progesterone hormones. It works by stopping ovulation each month (think: no egg, no risk of fertilisation). It also thins the uterine lining; and thickens the mucus produced by the cervix, making it difficult for sperm to pass into the female reproductive tract.

Apart from its contraceptive effect, the combined pill also causes more regular, lighter periods (yippee!), and less PMS (such as period pain). However, for some, it is associated with side effects, such as nausea, headaches and an increased appetite (this can lead to weight gain).

Importantly, there are some possible serious (although less common) complications associated with the use of the combined pill. These include DVT, heart attack and strokes. Use of the combined pill is therefore not recommended for those with risk factors for certain conditions, such as hypertension and a history of blood clotting. If you are over 35 years and smoke, or are overweight, it may also be recommended that you consider an alternate form of contraception.

There are different types of combined pill, and many different brands:

a) Monophasic pills: Each active pill has the same level of oestrogen and progestogen hormones in them. Examples of these include Microgynon30 and Yasmin (or the lower oestrogen-containing pills, Microgynon20 and Yaz ). Yasmin and Yaz contain the progestogen drospirenon, which may help reduce premenstrual bloating but may carry a slightly greater risk of clotting.

b) Multiphasic pills: These pills contain two or three different doses of hormones. Examples include Trifeme , Triphasal and Logynon.

c) Third generation pills: These pills are monophasic, and contain the progestogens desogestrel or gestodene. They were developed to counteract the side effects of other combined pills. However, they have also been associated with a slightly greater risk of blood clotting. Examples include Minulet.

Because each individual may react differently to any given pill, it is usual practice for the GP to start you on a combined monophasic pill, and then swap you to a different pill if you experience side effects. It is important that your doctor gets a good history from you to ensure you are on the most effective and safest choice.

The mini-pill
The mini-pill contains only synthetic progesterone hormone. Brands include Micronor and Microlut. This pill works by thickening the cervical mucus, and by thinning the uterine lining. It is used in situations when the combined pill is not a safe option, and can be taken when breastfeeding. For effectiveness, it should be taken at about the same time each day.

Because the mini-pill does not contain oestrogen, it is not associated with the same increased risks of DVT and cardiovascular problems. Weight gain also occurs less commonly. However, breakthrough bleeding can occur.

The 'pill' and cancer risk
The 'pill' may slightly increase a woman's risk of developing breast cancer. This risk disappears within about 10 years of stopping the oral contraceptive pill. On the plus side, the 'pill' may reduce the risk of other cancers, such as ovarian cancer.

Long-term use and fertility
Many women are concerned that using the 'pill' in the long-term could affect their fertility once they are ready to conceive. However, the good news is that there is no direct connection between how long the pill has been used and fertility issues.

Some women find that when they do stop the 'pill', it can take considerable time to fall pregnant. But this may be due to the fact that the 'pill' had been masking an underlying problem, such as irregular menstruation. In addition, the longer you are on the 'pill' the older you are likely to be getting … and fertility does decline after the age of 35 years.