Maternal medical care (prenatal and postpartum) involves a set of clinical interventions addressing risk factors associated with important maternal and infant outcomes. Programs to increase the rate of delivery of these interventions in clinical practice have not been widely implemented. A practice-based research network focused on developing continuous quality improvement (CQI) processes for maternal care among 10 family medicine residency training sites in the northeastern United States (the IMPLICIT Network) from January 2003 through September 2007. Documented delivery of 5 standard maternal care interventions was assessed before and after initiating a program to increase their frequency. Proportion chart analyses were conducted comparing the period before and after implementation of the CQI interventions. Data were available for 3936 pregnancies during the course of the study period. Results varied across the clinical interventions. Significant improvement in care processes was seen for 3 screening activities: (1) prenatal depression symptomatology (by 15 weeks' gestation); (2) screening for smoking at 30 weeks' gestation; (3) and postpartum contraception planning. Screening for smoking by 15 weeks' gestation and testing for asymptomatic bacteriuria were already conducted >90% of the time during the baseline period and did not increase significantly after initiating the CQI program. Screening for postpartum depression symptomatology was recorded in 50% to 60% of women before the CQI program and did not increase significantly. A practice-based research network of family medicine residency practices focused on CQI outcomes was successful in increasing the delivery of some maternal care interventions.