METHODS: In terms of the effects of such interventions, empirical research has shown inconclusive results. This meta-analysis applies 12 effect sizes from 12 independent empirical studies, with a total of 640 participants, to assess the overall impact of interventions on students' hardiness and to test for moderators, in light of the contradictory findings in prior work. The current meta-analysis calculates the standardized mean differences (SMD) of pre-post interventions. The level of study heterogeneity, represented by I 2, was interpreted as small (I 2 ≤ 25%), moderate (25% < I 2 ≤ 50%), substantial (50% < I 2 ≤ 75%), or considerable (I 2 > 75%). Twelve studies met the inclusion criteria and were included in the meta-analysis.
RESULTS: The results show that the interventions had a significant positive overall effect on students' hardiness (g = 0.998, k = 12) and show significant heterogeneity among effect sizes. Among the interventions, cognitive-based intervention yielded the largest mean effect size (g = 2.015, k = 5). Furthermore, moderator analyses suggest that the effects of the interventions on students' hardiness are moderated by respondent type, culture, intervention type, research design, years, and duration of intervention.
DISCUSSION: We conclude that interventions that promote students' hardiness are officious. Despite the low homogeneity of the results and limitations of this meta-analysis (e.g., a small number of included studies) which might have influenced the findings, the large fail-safe N suggests that these findings are robust. The study examined potential causes of heterogeneity and emphasized the importance of further research in this area.
METHODS: The literature was searched via the PubMed, Embase, Cochrane Library, and Web of Science databases. Weighted mean difference (WMD) or the risk ratio (RR) was used as the effect indicator, and the effect size was represented by the 95 % confidence interval (CI). Subgroup analysis based on the perinatal stage, physical activity intensity, physical activity equivalent, and intervention duration was performed.
RESULTS: Totally, 35 studies including 5084 women were included. Physical activity could reduce the incidence and severity of depression in perinatal women. Among depressed women with prenatal depression, low-intensity physical activity, with metabolic equivalents (METs)-min/week being <450, was associated with lower levels of depression. In the general population, the risk of postpartum depression was lower in the physical activity group when the duration of intervention was ≥12 weeks, being II, III stage, and ≥450 METs-min/week. Both low and moderate-intensity physical activity were beneficial to an improved depression severity among depressed women with postpartum depression, and moderate exercise intervention could decrease the risk of postpartum depression in general pregnant women.
LIMITATIONS: Different types of physical activities may affect the effectiveness of interventions.
CONCLUSION: Our study indicated physical activity specifically targeted at pregnant women could reduce depression risk and severity.