BACKGROUND: More than 50% of women who have an unplanned pregnancy report using a contraceptive method. Since the launch of the pill 50 years ago, a number of cross-sectional surveys have examined contraceptive use in the Australian context. There is, however, little data on contraceptive use and efficacy over a woman's reproductive years. AIM: To determine the pattern of contraceptive use of Australian women over their reproductive lifespan, with particular emphasis on the relationship between contraceptive use and pregnancy. METHOD: One thousand women from the mid-age cohort of the Australian Women's Longitudinal Study were invited to participate in the Family Planning survey by completing a questionnaire about their reproductive histories. RESULTS: Completed questionnaires were received for 812 women. The contraceptive pill was the most commonly ever used contraceptive method at 94% and also the most commonly used method prior to all pregnancies. Contraceptive failure increased with increasing gravidity; 11.4% with the first pregnancy to 23.0% with the fourth pregnancy, while 28.8% of the respondents reported an 'accidental' pregnancy due to stopping contraception for reasons such as concern about long-term effects and media stories. CONCLUSIONS: While surveys indicate that 66-70% of Australian women use a contraceptive method, more than half of unplanned pregnancies apparently occur in women using contraception. The modern Australian woman, in common with her predecessors, still faces significant challenges in her fertility management. This survey provides a longitudinal perspective on contraceptive use in relation to pregnancy and highlights the issue of efficacy of contraceptives in real-life situations.