MKI67 and hydrops fetalis: Fig. 4A shows the increased frequency of high expression of this proliferative marker among the NHB women in our study relative to the NHW, HF, and HPR women. Figure 4B demonstrates the fraction of patients in each cohort above and below the 14 percent positive nuclei cutoff. Supplementary Figure S5 and Supplementary Table S13 extend the analysis of Fig. 4, summarizing Ki-67 percent positivity by clinical subtype and by cohort.