From: Rabbi Moshe Sofer
To: Rabbi Hersh of Aglid
The Chasam Sofer defends the Rokeach's position that Shehecheyanu should not be recited at circumcision due to concern the child may be a nefel, distinguishing between obligatory blessings (where we rely on the majority) and optional blessings like Shehecheyanu (where we do not, given the common minority of doubtful nefalim). He further argues that a safek ben shmoneh should not be circumcised on Shabbos at all, as it would create an irresolvable conflict between endangering the child and desecrating Shabbos for pikuach nefesh.
Source: Shu"t Chasam Sofer YD §247