What is the burden of proving a plaintiff's claim of discrimination against a defendant by a preponderance of the evidence?

In short, the jury should have been instructed that if it found plaintiff had demonstrated by a preponderance of the evidence that her pregnancy played a part in defendant's decision, then it should find for plaintiff unless defendant demonstrated by a preponderance of the evidence that the same decision would have been made even if pregnancy had not been one of the factors contributing to it. See Price Waterhouse, 490 U.S. at 244-45, 109 S.Ct. at 1787-88. See also Kump v. Xyvision, Inc., 733 F.Supp. 554, 561-62 (E.D.N.Y.1990) (applying similar standard to pregnancy discrimination claim under New York's Human Rights Law). The trial court's instruction erroneously failed to delineate clearly each party's burden in this case.