Box and whisker plots of factors associated with log10 transformed maternal-fetal DNA admixture: (A) HIV-1 vertical transmission status, (B) preterm delivery (<37 weeks gestation), (C) low CD4 T-cell counts (<200 cells/ml), (D) low birth weight (<2500 grams). NT=uninfected infant; IU= in utero-infected infant; IP=intrapartum infected infant. Line represents median value, box edges represent 25th and 75th percentile, whisker edges represent upper adjacent values, and dots represent outside values. P-values were determined by the Wilcoxon rank-sum test.