Every pharmacy has a duty to fill legal prescriptions. Refusing a woman birth control isn't just inconvenient, it's dangerous for women.
A pharmacist who opposes birth control can step out of the way, but he shouldn't get in the way of a woman's access to birth control. Plus, some women take birth-control pills for reasons other than preventing pregnancy. Should a woman in this situation be forced to tell the pharmacist this private information in a public place like the pharmacy counter?
The bottom line is: a woman's birth control is her business – and nobody else's.