Romplostim serum and breast milk analysis. (A) Schematic of the proteomics workflow. (B) Romiplostim amino acid sequence, which highlights the unique domain (blue). (C) Serum measurements using unique peptide intensities, as identified using Maxquant analysis, of the pregnant participants’ blood and cord blood at the time of delivery (day 3 after romiplostim dose) compared with a blood sample of the pregnant participant when not receiving romiplostim and 2 nonpregnant women (ie, nonpregnant controls). (D) Serum measurements using unique peptide intensities (MaxQuant) of the pregnant participants’ blood and cord blood at the time of delivery (day 3 after romiplostim dose) compared with a blood sample of the same pregnant participant when not receiving romiplostim and 2 nonpregnant controls. (E) Breast milk analysis using unique peptide intensities, as identified using MaxQuant analysis, in the control milk from 2 postpartum individuals and the participant (mother) on days 0.75, 1, and 7 (trough level) after taking romiplostim. (F) Postpartum romiplostim analysis on the same day as the participant’s blood and breast milk and infant’s blood (day 0.75 after romiplostim dose). Significance is denoted using a Student t test: ∗P < .05; ∗∗P < .01; and ∗∗∗P < .005.