This article studies a modular semistable elliptic curve EE over a totally real number field FF such that, upon base change to a totally imaginary quadratic extension KK, it has analytic rank one. Assuming the Iwasawa main conjecture, along with a substantial number of assumptions, we prove a variant of the pp-part of the Birch and Swinnerton-Dyer formula over KK, where pp is an odd prime. More precisely, up to a pp-adic unit, we have L(E/K,1)ΩfcongReg(E/K)=#Sha(E/K)[p]ucu(E/K),\frac{L'(E/K,1)}{Ω^{\mathrm{cong}}_{\mathbf{f}} \operatorname{Reg}(E/K)} = \# Sha(E/K)[p^\infty]\prod_{u} c_u(E/K), where ΩfcongΩ^{\mathrm{cong}}_{\mathbf{f}} is the congruence period of the Hilbert modular form f\mathbf{f} associated to EE via the modularity conjecture.