Relationship between physical activity and depression in postpartum women

Background: The postpartum period is a critical phase during a woman's life with important physical and psychological health implications for both mother and child. Postpartum women, for example, have reduced levels of physical activity (PA) compared to pre-pregnancy, may find it difficult to lose weight gained during pregnancy, and are at an increased risk of suffering from depression.

Physical activity (PA) is almost universally acknowledged to have a wide array of significant health benefits and postpartum women, in particular, can benefit greatly from PA. Postpartum PA has been shown to have important physical (improving aerobic fitness) and mental health (reducing postpartum depression symptoms) benefits. Reliable estimates for levels of PA activity among postpartum women are not available. This study uses data from the 2005 Oregon Pregnancy Risk Assessment System (PRAMS), a population-based sample of recent mother, to estimate the prevalence of postpartum PA. The purpose of PRAMS is to assess maternal attitudes and experiences before, during, and shortly after pregnancy. To our knowledge, this is the first estimate of PA among postpartum women on a state-wide level.

Objectives: The main goals of this study were to estimate the prevalence of insufficient physical activity (PA) using a population-based sample of recent Oregon mothers and to identify significant risk factors for getting insufficient PA. In particular, this study examined the contribution of self-reported postpartum depression (SRPPD) as a risk factor for getting insufficient PA.

Methods: The 2005 Oregon PRAMS sample was drawn from all Oregon mothers who gave birth in 2005. Sample weights were corrected for over-sampling and adjusted for non-response rates. A total of 1915 women responded to the 2005 Oregon PRAMS (adjusted response rate of 75.6%). Women who did not respond to the single PA question (n = 57, 3.0%) were excluded from the analysis. Women who were not living with their newborn at the time of the survey (n = 40, 2.1%) or women whose child was not alive at the time of the survey (n = 16, 0.8%) were also excluded. These exclusions resulted in a final sample of 1,803 mothers.

The main outcome variable, postpartum PA, was assessed using a single question: “In the past month, how many days a week did you get at least 30 minutes of physical activity or exercise? (For example, walking, dancing, yard work, or sweeping.).” Women who reported getting at least 30 minutes of moderate PA at least 5 days/week were considered as having sufficient PA, as defined by the CDC. SRPPD was assessed using the following two questions: (1) “Since your new baby was born, how often have you felt down, depressed, or hopeless?” (2) “Since your new baby was born, how often have you had little interest or little pleasure in doing things?” A response of either “Always” or “Often” on either of the two questions was interpreted as having SRPPD.

Risk factors for getting insufficient PA, including SRPPD, were assessed using logistic regression modeling. All percentages, odds ratios (OR), and 95% confidence intervals (CIs) were weighted to reflect the complex survey design of the PRAMS.

Results: We found that a large proportion (73.6%, C.I. = 70.2 - 76.7%) of Oregon women reported getting insufficient PA. In addition, the prevalence of self-reported postpartum depression (SRPPD) was 10.5% (95% C.I. = 8.5 - 12.8%). SRPPD was a major risk factor for getting insufficient PA among our sample of recent mothers. For example, mothers with SRPPD had more than twice the odds of getting insufficient PA (adjusted OR = 2.28, 95% C.I. = 1.23 - 4.24) compared to mothers without SRPPD, after adjusting for maternal race/ethnicity, age, education, and health status, as well as the child's age and health status.

Discussion: Our results show that almost 74% of recent Oregon mothers reported not getting sufficient levels of PA as recommended by the CDC and American College of Sports Medicine. This finding is of concern, especially if it is representative of PA levels across the postpartum period. The prevalence of SRPPD was consistent with previous findings. However, SRPPD was a major risk factor for getting insufficient PA in postpartum women. Causality between insufficient PA and depression in postpartum women remains to be established, however it may go both ways, with depressed women likely to get less PA and women with low PA more susceptible to depressive symptoms. Postpartum depression is the most prevalent health complication resulting from childbirth and therefore, its role as a significant risk factor for getting insufficient PA has important public health implications. There is substantial evidence that PA by mothers following birth has direct physical and psychological benefits (including reducing postpartum depression). Therefore, increasing PA levels in postpartum women could have significant short and long-term health benefits for both mothers and their children.

Conclusions: The prevalence of insufficient PA activity in Oregon mothers is high. PA has a variety of health benefits for mothers and their offspring. Thus, interventions designed to increase PA in postpartum women have the potential to significantly improve the public health of women and their children.