What does the research tell us about a particular area? What questions are answered? What questions still need to be answered? What research is still needed?

Research review on interventions to reduce opioid use disorder (OUD) for pregnant women in the U.S

Note that research reviews are not simply lists of studies with findings, or descriptions of a set of studies.  A research review should be integrative; what does the research tell us about a particular area?What questions are answered? What questions still need to be answered? What research is still needed?