Prevalence of Self-Reported Postpartum Depressive Symptoms --- 17 States, 2004--2005

Postpartum depression (PPD) affects 10%--15% of mothers within the first year after giving birth (1). Younger mothers and those experiencing partner-related stress or physical abuse might be more likely to develop PPD (2,3). CDC analyzed data from the Pregnancy Risk Assessment Monitoring System (PRAMS) for 2004--2005 (the most recent data available) to 1) assess the prevalence of self-reported postpartum depressive symptoms (PDS) among mothers by selected demographic characteristics and other possible risk factors for PDS and 2) determine factors that identify mothers most likely to develop PPD. This report summarizes the results of that analysis, which indicated that, during 2004--2005, the prevalence of self-reported PDS in 17 U.S. states* ranged from 11.7% (Maine) to 20.4% (New Mexico). Younger women, those with lower educational attainment, and women who received Medicaid benefits for their delivery were more likely to report PDS. State and local health departments should evaluate the effectiveness of targeting mental health services to these mothers and incorporating messages about PPD into existing programs (e.g., domestic violence services) for women at higher risk.

PRAMS is an ongoing, state-specific, population-based surveillance project that collects self-reported information on maternal attitudes and experiences before, during, and after delivery of a live infant. PRAMS is administered by CDC in collaboration with participating states and cities and is designed to be representative of women in participating states who have delivered during the preceding 2--6 months (4). Response rates were >70% for 2004 and 2005 in each of the 17 participating states. During 2004--2005, these 17 states included two questions on self-reported PDS in their PRAMS surveys: 1) "Since your new baby was born, how often have you felt down, depressed, or hopeless?" and 2) "Since your new baby was born, how often have you had little interest or little pleasure in doing things?" The response choices were "always," "often," "sometimes," "rarely," and "never"; women who said "often" or "always" to either question were classified as experiencing self-reported PDS. Because of their high sensitivity (96%), these two questions have been recommended as a depression case-finding instrument by health professionals (5,6). Chi-square tests were used to test for significant differences (p<0.05) in the proportion of women reporting PDS by demographic characteristics and other possible risk factors for PDS within each of the 17 states; approximate 95% confidence intervals for these proportions were calculated.† To measure the strength of the association overall, the median difference across all states in the proportion of women reporting PDS between two levels of each covariate was calculated. Sample sizes varied for each estimate because women who were missing data on any variable (<5% of all women) were excluded from analysis of that variable. The analysis was conducted using statistical software to adjust for the complex survey design and produce statewide estimates. Estimates based on small sample sizes (fewer than 30 respondents) were considered to be unreliable.

The maternal characteristics analyzed included age at delivery, race/ethnicity, education, marital status, and receipt of Medicaid for delivery. Possible risk factors for PDS included in the analysis were low infant birth weight (<2,500 g), admission to a neonatal intensive-care unit (NICU), number of previous live births, tobacco use during the last 3 months of pregnancy, physical abuse before or during pregnancy, and experiencing emotional, financial, partner-related, or traumatic stress§ during the 12 months before delivery. Women were considered physically abused if they said that a current or former husband/partner had pushed, hit, slapped, kicked, choked, or physically hurt them in any way during the 12 months before or during the most recent pregnancy. Women who reported smoking one or more cigarettes on an average day were classified as using tobacco during the last 3 months of pregnancy.

During 2004--2005, overall prevalence of self-reported PDS ranged from 11.7% (Maine) to 20.4% (New Mexico) (Table 1). Demographic characteristics significantly associated with PDS in all of the 17 states were maternal age, marital status, maternal education, and Medicaid coverage for delivery. Among the 17 states, the median percentage point difference in PDS prevalence was 13.4 percentage points between the youngest and oldest mothers, 13.6 between the lowest and highest education groups, 9.7 by marital status, and 11.0 by Medicaid receipt. In 13 of the 16 states for which data were available, a significant association was observed between race/ethnicity and PDS, with non-Hispanic white women having a lower prevalence of PDS compared with women of other racial/ethnic groups.

PDS was significantly associated with five possible risk factors in all or nearly all of the 17 states (Table 2). The number of states with significant associations and state median percentage point differences in PDS prevalence for women with and without these risk factors were using tobacco during the last 3 months of pregnancy (16 states; median difference: 10.7), physical abuse before or during pregnancy (17 states; median difference: 22.4), partner-related stress during pregnancy (17 states; median difference: 16.4), traumatic stress during pregnancy (17 states; median difference: 16.4), and financial stress during pregnancy (17 states; median difference: 9.2). In 14 states, PDS was significantly associated with delivering a low birth weight infant and experiencing emotional stress during pregnancy. NICU admission was associated with PDS in nine states. The state median percentage point differences in PDS prevalence were 5.7 by low birth weight delivery, 5.2 by emotional stress, and 6.2 by NICU admission. The effect of parity on PDS was unclear; the association was significant in only two states, and the results were inconsistent across all states regarding risk for developing PDS.

Reported by: K Brett, PhD, Office of Analysis and Epidemiology, National Center for Health Statistics; W Barfield, MD, Div of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion; C Williams, ScD, EIS Officer, CDC.