29 C.F.R. § 1636.4
(a) It is an unlawful employment practice for a covered entity not to make reasonable accommodations to the known limitations related to the pregnancy, childbirth, or related medical conditions of a qualified employee, unless such covered entity can demonstrate that the accommodation would impose an undue hardship on the operation of the business of such covered entity.
(1) An unnecessary delay in providing a reasonable accommodation to the known limitations related to the pregnancy, childbirth, or related medical conditions of a qualified employee may result in a violation of the PWFA, 42 U.S.C. 2000gg-1(1), even if the covered entity eventually provides the reasonable accommodation. In determining whether there has been an unnecessary delay, factors to be considered, with no one factor to be dispositive, include:
(3) A covered entity cannot justify failing to provide a reasonable accommodation or the unnecessary delay in providing a reasonable accommodation to a qualified employee with known limitations related to pregnancy, childbirth, or related medical conditions based on the employee failing to provide supporting documentation, unless:
(d) It is an unlawful employment practice for a covered entity:
(e) It is an unlawful employment practice for a covered entity: