To evaluate the impact of a community-based, collaborative, shared antenatal care intervention (the Mums and Babies program) for Indigenous women in Townsville. Prospective cohort study of women attending Townsville Aboriginal and Islander Health Service (TAIHS) for shared antenatal care with a singleton Indigenous birth between 1 January 2000 and 31 December 2003 (456 women; the MB group), compared with a historical control group of 84 women who attended TAIHS for antenatal care before the intervention between 1 January 1998 and 30 June1999, and a contemporary control group of 540 women who had a singleton birth at Townsville Hospital between 1 January 2000 and 30 June 2003, but did not attend TAIHS for antenatal care. Integration of previously autonomous service providers delivering shared antenatal care from TAIHS. Patterns of antenatal visits, proportion of women undertaking key antenatal screening, and perinatal outcomes. The number of Indigenous women who entered the MB program and gave birth at Townsville Hospital rose from 23.8% in 2000 to 61.2% in 2003. The number of antenatal care visits per pregnancy increased from three (interquartile [IQ] range, 2-6) in the historical control group to seven (IQ range, 4-10) in the MB group (P < 0.001). 88% of women in the MB group had at least one ultrasound. About 90% of all women attending for antenatal care were screened for sexually transmitted infections. In the MB group, there was a significant reduction in preterm births compared with the contemporary control group (8.7% v 14.3%, P < 0.01). There was no significant reduction in the prevalence of low birthweight births or perinatal mortality. A community-based collaborative approach to shared antenatal care services increased access to antenatal care and was associated with fewer preterm births among Indigenous women in Townsville. The model may be adaptable in other urban centres with multiple antenatal care providers and significant numbers of Indigenous people across Australia.