This really has to be considered on a state, district, and school basis. Everything is so different, and if some parents say they don't want their children to learn something, there is nothing you can do. Consult your school's policy on controversial topics, see what is already being taught in regards to health (puberty, periods, personal touch, etc.) and go from there.

I feel like if you want to reach out to students that have overprotective students about something that they are going to need to know at some point, is possibly reach out to the students parents and ask them if it is okay if their student sits through the class. Otherwise, make sure to tell the parents that they are offered this class through the school and it teaches them stuff that they need to know.

You can explain to the parents what you are teaching and why you are teaching it and this may make them a little more comfotable.