A recent joint study by The School of Public Health and The Department of Medical Education, Faculty of Health Sciences, both of Curtin University, Perth assessed a total of 384 women. Information sought included demographic and lifestyle characteristics such as the use of condoms for contraception, consumption of oral contraceptives and duration of oral contraceptive usage.

Cervical intraepithelial neoplasia (CIN) is initiated by human papillomavirus (HPV) infection. Sexual and reproductive behaviours as well as hormone levels and hormone receptors, are know to affect the development of CIN. Besides vaccination, use of condoms is an effective barrier against HPV infection, and may reduce the risk of CIN among women highly susceptive to HPV infection. The purpose of the study was to ascertain its protective effect on other women.

The transforming zone of the cervix, where HPV initiates CIN, is sex-hormone dependent. Steroid hormones including progesterone, influence HPV actions and indirectly contribute to HPV-related CIN. Despite the widespread use of oral contraceptives and its protective effect against cancers affecting women, such as endometrial cancer, there is no consensus on the use of oral contraceptives and the health of the cervix.

While a joint report by the World Cancer Research Fund and The American Institute for Cancer Research suggested a possible increased risk of cervical cancer, the World Health Organisation did not recommend discontinuing the use of oral contraceptives as its use outweighed the risk.

The Perth study results showed that the prevalence of CIN was found to be 15.8% (55/348 participants). Most of the participants were married (99%) and never smoked (62%). Women with CIN tended to be younger and earned less than those without CIN. Body mass index, lifestyle and reproductive characteristics were similar between the two groups.

The duration of cumulative oral contraceptive consumption among women without CIN was significantly longer than those with CIN. The study further showed that long term consumption of oral contraceptive for at least 10 years was associated with a reduced risk when compared to 3 years or less usage.

Despite the limitations, the study found that prolonged oral contraceptive use was associated with a decreased risk of CIN, therefore the protective benefits of oral contraceptives outweighed the adverse effects and their use should not be discontinued without consultation with a doctor.