Objective Few postpartum ethnic minority women perform leisure-time moderate-to-vigorous physical activity (MVPA). The study tested the effectiveness of a 12-month tailored intervention to increase MVPA in women with infants 2–12 months old. Methods From 2008–2011, women (n=311) with infants (average age = 5.7 months) from Honolulu, Hawaii were randomly assigned to receive tailored telephone calls and access to a mom-centric website (n=154) or access to a standard PA website (n=157). MVPA was measured at baseline, 6, and 12 months using self-report and acclerometers. Results Controlling for covariates, the tailored condition significantly increased self-reported MVPA from an average of 44 to 246 minutes/week compared with 46 to 156 minutes/week for the standard condition (p=0.027). Mothers with ≥ 2 children had significantly greater increases in MVPA in response to the tailored intervention than those with one child (p=0.016). Accelerometer-measured MVPA significantly increased over time (p=0.0001), with no condition differences. There was evidence of reactivity to initially wearing accelerometers; the tailored intervention significantly increased MVPA among women with low baseline accelerometer MVPA minutes, but not among those with high minutes (pinteraction=0.053). Conclusion A tailored intervention effectively increased MVPA over 12 months in multiethnic women with infants, particularly those with more than one child.

During the postpartum period, ethnic minority women have higher rates of inactivity/under-activity than white women. The Nā Mikimiki (“the active ones”) Project is designed to increase moderate-to-vigorous physical activity over 18 months among multiethnic women with infants 2–12 months old. The study was designed to test, via a randomized controlled trial, the effectiveness of a tailored telephone counseling of moderate-to-vigorous physical activity intervention compared to a print/website materials-only condition. Healthy, underactive women (mean age = 32 ± 5.6 years) with a baby (mean age = 5.7 ± 2.8 months) were enrolled from 2008–2009 (N = 278). Of the total sample, 84% were ethnic minority women, predominantly Asian–American and Native Hawaiian. Mean self-reported baseline level of moderate-to-vigorous physical activity was 40 minutes/week with no significant differences by study condition, ethnicity, infant's age, maternal body mass index, or maternal employment. Women had high scores on perceived benefits, self-efficacy, and environmental support for exercise but low scores on social support for exercise. This multiethnic sample's demographic and psychosocial characteristics and their perceived barriers to exercise were comparable to previous physical activity studies conducted largely with white postpartum women. The Nā Mikimiki Project's innovative tailored technology-based intervention and unique population are significant contributions to the literature on moderate-to-vigorous physical activity in postpartum women.

Approximately 70% of new mothers do not meet national guidelines for moderate-to-vigorous physical activity (MVPA). The Nā Mikimiki (“the active ones”) Project (2008-2011) was designed to increase MVPA among women with infants 2-12 months old. Participants’ barriers to exercising and achievement of specific MVPA goals were discussed during telephone counseling calls over 12-months. Healthy, inactive women (n=115, mean age=31 ±5 years, infants’ mean age = 5.5 ± 3 months; 80% racial/ethnic minorities) received a total of 17 calls over 12 months, in three phases. During Phase 1 weekly calls were made for a month; in Phase 2 biweekly calls were made for two months, and in Phase 3 monthly calls were made for nine months. Across all Phases, the most frequent barriers to achieving MVPA goals were: time/too busy (25%), sick child (11%), and illness (10%). Goals for MVPA minutes per week were achieved or surpassed 40.6% of the time during weekly calls, 39.9% during biweekly calls and 42.0% during monthly calls. The least likely MVPA goals to be achieved (p < 0.04) were those which the woman encountered and for which she failed to overcome the barriers she had previously anticipated would impair her improvement of MVPA. This process evaluation demonstrated that telephone counseling somewhat facilitated the resolution of barriers and achievement of MVPA goals; thus, if clinical settings adopted such methods, chronic disease risks could be reduced in this vulnerable population of new mothers.

Understanding theoretically derived social and behavioral mediators of long-term increases in physical activity (PA) in a vulnerable population at risk for being underactive is needed to inform future research, clinical applications, and public health efforts. This is an analysis of potential mediators of an intervention that increased long-term (12-month) moderate to vigorous physical activity (MVPA) in postpartum (2–12 months) women in a randomized trial, using a longitudinal analysis. Healthy, underactive (i.e., not meeting national guidelines for MVPA) women (n = 311; mean age = 32 ± 5.6 yr, 85% minorities) with infants (mean age: 5.7 ± 2.8 months) were randomly assigned to either a tailored eHealth condition consisting of personalized telephone counseling plus access to a website tailored to new mothers’ MVPA issues or to a standard MVPA materials-only website. MVPA was assessed via surveys completed at baseline, then 6 and 12 months later. Theoretically derived mediators included social support for MVPA, self-efficacy to increase MVPA, barriers to increasing MVPA, and benefits of increasing MVPA. All mediators, except benefits, improved over the 12 months in the tailored eHealth condition. The tailored condition’s effect on increasing MVPA from 6 to 12 months was mediated by an increase in social support from baseline to 6 months. No other hypothesized mediators were significant. Our results demonstrated that learning strategies to increase social support for MVPA was instrumental in new mothers’ increase in MVPA over a 12-month intervention. During this brief but impactful life stage, where the focus can understandably be on her baby, being able to elicit support from friends and family may facilitate women’s efforts to focus on their own needs with respect to MVPA. Trial Registration: Clinical Trials.gov number: NCT00810342.

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