Nonimmune hydrops fetalis: identifying the underlying genetic etiology.

Purpose: Numerous etiologies may lead to nonimmune hydrops fetalis (NIHF), and the underlying cause often remains unclear. We aimed to determine the proportion of NIHF cases in which the etiology was clearly determined in a large, contemporary, and diverse cohort, as well as to describe the etiologies with a focus on genetic causes.

Methods: Retrospective review of NIHF cases between 2015 and 2017 from the five University of California Fetal-Maternal Consortium sites.