The aim of this study is to examine the relationship between prenatal care (PNC) provider site and the extent of documented adherence to recommended PNC content, and the relationship between adherence to recommended PNC content and adverse pregnancy outcomes among women in Illinois' Medical Assistance Program (MA). Utilizing the medical record, MA claims, and birth certificate data of 374 women who gave birth in 2003 and 2004 in four high-risk communities in Chicago, crude and adjusted analyses of the relationship between provider site and the extent of documented adherence to PNC content, and between adherence to PNC content and the incidence of low birthweight (LBW) and preterm birth (PTB) were conducted. The extent of documented adherence to recommended PNC content was measured from medical records as the percentage of 19 components of standard obstetrical practice that were delivered during pregnancy, converted to a three level categorical variable (low 50%, medium 50-79% and high 80% or greater). The majority of women had less than 80% of the recommended PNC content documented in their medical records. Among high-risk women, a greater proportion of women served by hospitals received care in which the extent of documented adherence was high (≥80%) compared to women served by physicians'offices (P < 0.05). Among low-risk women, a greater proportion of women served by FQHCs received care in which the extent of documented adherence was high compared to women served by hospitals (P < 0.10). Lower adherence to PNC content was significantly associated with LBW and PTB among women receiving prenatal care from physicians. Examination of the extent of adherence to recommended PNC content and its relationship to adverse pregnancy outcomes provides valuable data to inform potential interventions. In particular, a relationship between adherence to recommended PNC content and LBW and PTB among women receiving PNC at physicians' offices suggests the importance of increased quality assurance and provider education efforts.