What kind of approach to inform superior about pregnancy if the superior is against employees getting pregnant? A male superior.

Sounds like a sexist. Anyway, I would just inform that superior that I am pregnant. Should the superior be exceptionally difficult, I would escalate to HR on workplace bullying or write to MOM anonymously about the bully. No matter what, do not resign cos it's very very difficult to find another job while pregnant and you may not get paid maternity leave.

There is not other way but to be frank about it. No superior is allowed to be against employees getting pregnant. We are there to work. but not there for them to allowed them rule our life.