This article studies a modular semistable elliptic curve over a totally real number field such that, upon base change to a totally imaginary quadratic extension , it has analytic rank one. Assuming the Iwasawa main conjecture, along with a substantial number of assumptions, we prove a variant of the -part of the Birch and Swinnerton-Dyer formula over , where is an odd prime. More precisely, up to a -adic unit, we have where is the congruence period of the Hilbert modular form associated to via the modularity conjecture.

