Icterus gravis (erythroblastosis) neonatorum.

Darrow was the first to identify the cause of hemolytic disease of the newborn (HDN). Three years prior to the discovery of antibodies against the Rh antigen, Darrow correctly hypothesized that the disease was caused by destruction of red blood cells due to antibodies in the mother's blood. Darrow's research was inspired by her personal experiences with the disease.

(Thanks to Juan Weiss for this reference and its interpretation.)