Pupils from three valley schools got together for a performance of Other by Is It? - a theatre-in-education company based jointly in Usk and Cardiff.
The play, written by director Catherine McGowan, focused on three women.
Two were unexpectedly pregnant, one is married but decides to have an abortion despite her husband's opposition, while the other, who is single, wants to keep the baby despite being disowned by her family.
The third woman finds out she has caught chlamydia and is now infertile.
Pupils from Lewis school, Pengam; Lewis girls' school, Ystrad Mynach; and Rhymney comprehensive were then challenged to think about abortion, teenage pregnancies and sexually transmitted diseases from ethical, moral and religious standpoints.
Laura Bevington, head of RE at Lewis school, which hosted the event, said:
"We wanted pupils to think about the consequences of a sexually transmitted disease or, if a girl, getting pregnant and maybe having an abortion."
Matthew Evans, of Lewis boys school, said: "The play gave us a lot of new information and the discussion touched on lots of things which affect people our age."
Joanne Parslow, of Lewis girls school, said: "We knew about chlamydia. But to see how it could affect you for the rest of your life was quite scary."