What does the C standard say about pointers to structs and their first member?

Consider the following two struct:

struct a
{
    int a;
};

struct b
{
    struct a a_struct;
    int b;
};

the following instantiation of struct b:

struct b b_struct;

and this condition:

if (&b_struct == (struct b*)&b_struct.a_struct)
    printf("Yes\n");

Does the C standard mandate this to always evaluate true?