Maternal postpartum depression (PPD) has an impact on mothers and infants. The American Academy of Pediatrics recommends screening for PPD at well-child visits during the first 6 months. We conducted a secondary data analysis of depression screening data collected each month during months 1 to 12 postpartum for 152 mothers with an infant participating in a randomized controlled trial. We used descriptive statistics to describe the incidence and the cumulative incidence of a positive PPD screen during months 1 to 12 postpartum. The results indicate that the initial positive screen for PPD can occur any time during the first 12 months postpartum and 15% had their first positive screen between months 6 and 12. Additionally, positive PPD screens are consistently high throughout the first year postpartum with the highest rate of positive screens at 12 months postpartum (23%). Our data suggest that PPD screening through 12 months may be most beneficial for families.