BACKGROUND: A wide range of health care options are utilised by pregnant women in Australia. The out-of-pocket costs of maternity care in Australia vary depending on many factors including model of care utilised, health insurance coverage, and women's decision to access health services outside of conventional maternity care provision. METHODS: Women from the 1973-78 cohort of the Australian Longitudinal Study on Women's Health (ALSWH) who identified as pregnant or as recently having given birth in 2009 were invited to complete a sub-study questionnaire investigating health service utilisation during their most recent pregnancy. RESULTS: A total of 1,835 women agreed to participate in the sub-study. The majority of women (99.8%) consulted with a conventional health care practitioner during pregnancy, 49.4% consulted with a complementary and alternative medicine practitioner at least once during pregnancy and 89.6% of the women used a complementary and alternative medicine product. Women reported an average of AUD$781.10 in out-of-pocket expenses for consultations with conventional health care practitioners, AUD$185.40 in out-of-pocket expenses for consultations with complementary and alternative medicine practitioners and AUD$179.60 in out-of-pocket expenses for complementary and alternative medicine products. From the study data we estimate Australian pregnant women spend over AUD$337 M on out-of-pocket health services. CONCLUSION: While the majority of pregnant women in Australia may obtain health services via the publically-funded health care system and/or private health insurance coverage, our analysis identifies substantial out-of-pocket expenditure for health care by pregnant women - a trend in public spending for maternity care of importance to policy makers, health administrators, and health professionals.