Strengths and limitations
The primary strength of this study is that it was focused on an understudied and at-risk population, with education and home visits being performed by members of the community. In addition, there is a paucity of research that has evaluated the effect of the provision of a Finnish-style baby box, infant items in conjunction with safe sleep education, compared with education alone. Related to this, the study benefitted from the randomization of participants to the intervention (baby box) and control (diaper bag) groups. As far as limitations this study took place in an under-resourced community, where sleeping space and monetary resources are relatively limited, so these findings are not generalizable to more affluent contexts. There may have been bias introduced through in the community health workers, who were not blinded to the randomization. While 1 month and 6 month AAP safe sleep education was delivered to all participants, the clinical staff may have inadvertently reinforced the safe sleep concepts differentially to participants. Another limitation of the study design is that co-sleeping was considered the least safe practice, but we did not assess the safety of the other sleep surfaces, as mothers reported infants sleeping in many other places in the home, primarily other beds, cribs, bassinets, and hammocks. Additionally, the prenatal intention and post-birth behaviors relative to sleeping practices were self-reported, and this may have been affected by social desirability relative to the education received. The measures used for cigarette and alcohol/other drug use were limited and may have led to an underestimate of these characteristics. Finally, the baby box and diaper bag groups were similar demographically except in ethnicity. Compared with the diaper bag participants the baby box group was more likely to indicate mixed/Mestizo ethnicity, and this may have affected the relationship between intervention group and outcomes. This concern is somewhat mitigated by the inclusion of ethnicity as a control variable in the longitudinal GEE analysis. Larger studies using implementation science frameworks regarding acceptability, feasibility, and cultural resonance of the baby box and other portable sleep devices are warranted. With a larger number of participants in a future study, it would be ideal to also evaluate whether those who report using the baby box for infant sleep differ from those randomized to the same group but who may be using the box for a different purpose, in terms of infant sleep practices. While both of these subgroups may use the box as a visual cue to reinforce safer sleep, the mothers using the box for sleep have a higher ‘dose’ of box exposure and this may affect outcomes.