What questions still need to be answered?

I am going to do a research review on interventions to reduce opioid use disorder (OUD) for pregnant women in the U.S. I want to start with a description of the public health program and the implications it has on society, women, and children. I will discuss the current interventions treatments for pregnant women with OUD. Furthermore, I will be discussing the barriers that still exist in delivery for care as well as policy barriers. The objective of this research review is to gain an understanding of the current interventions for OUD in pregnant women in order to highlight the key research and policy opportunities that need to be considered.
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?