Effectiveness of Mobile Health-based Nutritional Interventions on Iron Status of Pregnant Women: A Systematic Review of Randomized Controlled Trials (Preprint)

Background: Anemia is a global health concern, with disproportionately higher prevalence among pregnant women in low-resource regions. International preventive and curative guidelines are available, although their implementation is questionable. To optimize implementation, the use of mHealth-based nutritional interventions is a potential option. Objective: To review available evidence on the effectiveness of mHealth-based nutritional interventions on the iron status of pregnant women. Methods: Searches were conducted in Embase, CINAHL, Cochrane Library, PubMed, Web of Science, Scopus, and supplemented by snowballing techniques to identify additional relevant studies from citation lists. Methodological quality of included studies was assessed (Risk of Bias (R.O.B 2.0 tool). The primary endpoint was the change in the mean hemoglobin concentration. Effect sizes were calculated as standardized mean differences (SMD), including Cohen’s d and Hedges’ g. Results: Of the 14,826 studies identified, only 11 randomized controlled trials were included. These studies employed different modes of delivery, including mobile phone calls (n=1), text messaging (SMS) (n=3), and mobile applications (n=4), with some utilizing more than two modes (n=3). The effect of mHealth-based nutritional interventions on iron status varied significantly. Four studies demonstrated a large effect size (2.61, 2.2, 1.61, 0.83), with three relying on WhatsApp Messenger as a mHealth delivery mode. Notably, interventions with the largest effect size (ES >0.8) achieved clinically significant improvements in Hb concentration, exceeding 1g/dL within- and between-group differences. However, including behavioral change theories and nutrition-sensitive components were not consistently associated with larger effect sizes. Due to the high heterogeneity (I2 >95%), attributed to variations in mHealth delivery modes, functions and interactive features across the included studies, meta-analysis could not be performed. Conclusions: This review demonstrates that mHealth-supported nutritional interventions effectively optimize Hb concentration in pregnant women. While text messaging was less effective in improving Hb concentration, combining it with another mHealth delivery mode, such as phone calls, improved intervention effectiveness. However, the variability in mHealth delivery modes, functions, and interactive features underscores the need for tailored strategies that account for context-specific challenges, digital literacy, and access to technology to enhance effectiveness.