As a general rule, I caution students against looking for research 'gaps.'  Gaps often exist for a reason: the question is hard to answer, uninteresting, etc. (See Dunleavy 2003, 'Authoring a PhD').  Even if a gap is genuinely important, as with a newly emerging field or issue (like Zika), there is no guarantee that you, as a student, will complete your research before another scholar answers that question.  Instead, I would encourage you to identify _problems_ in the existing literature.  Particularly if you have first-hand experience in an area (e.g., from previous professional work), you will often be able to look at the literature and find things that other scholars may have gotten wrong - perhaps because they lacked the ground-level perspective you bring.  If you can identify why they seem to have gotten it wrong (e.g., incorrect assumptions, sampling errors, etc.), you can then design research that will get it right.

In short, Carlos seems to suggest some interesting gaps.  But I would also encourage you to see if you can't create your own gap, by finding a piece of conventional wisdom that is flawed and needs to be reconsidered.

Thank you all for your responses they have helped me shape up my research topic 

Dear Vita,

I agree with Christopher. My experience in developing countries bold the access inequality to health centers& resources as youth friendly health services, so.

You can consider; The influence of parent-adolescent communication on adolescents' reproductive health