Firstly, a lectern is not a podium and a podium is not a lectern. Technically, you stand behind a lectern but you stand on a podium. The skills needed to be speaking behind a lectern are different than speaking in front of a lectern.
If you are speaking behind the lectern, there are many questions that have to be asked. What is the height of the lectern in comparison to you the speaker? How large is the lectern? Will there be a microphone or microphones on the lectern? Standing behind the lectern, can you be seen from all sections of the room? Where on stage will the lectern be placed?
I am six foot tall. As a result, if I stand behind a lectern, being seen is not an issue. More importantly, my gestures during my speech can easily be seen from the back of the room. Now, a five foot tall speaker would have more problems being visible. You may only see their head and the top of the shoulders using the same lectern. If you add microphones to the lectern, visibility is even more restricted. So any gestures they will make would have to be made almost over their shoulders and head. This would look very silly. The solution may be as simple as placing a riser for the speaker to stand on. Also where is the lectern going to be placed on the stage? If you are using a Power point presentation, the lectern maybe off to one side. Does the lectern have a light for you to see your notes and an easily accessible electrical outlet for your laptop? This is especially critical if the lectern is placed on stage where it is dark. There are many questions that need to be considered if you are speaking behind a lectern. These questions have to be addressed in advance of your speaking.
Now speaking in front of a lectern is similar to just speaking on a stage. That is another topic for a latter blog.