So much of subsections (b)(3), (c)(4), 1 (d)(5), (g)(3), and (h)(4) of this section as precedes the semicolon, shall not apply in the case of any child unless such child, at the time of the marriage referred to therein, was under a disability (as defined in section 423(d) of this title ) or had been under such a disability in the third month before the month in which such marriage occurred.