Figure. Natalizumab concentration in breast milk and blood samples of mothers and their breastfed infants.

Left: natalizumab concentrations (in micrograms per milliliter) in the breast milk of mothers 2 and 3 on several days after the first infusion postpartum and of mother 1 on several days after the fourth infusion postpartum. Right: natalizumab concentration (in micrograms per milliliter) in sera of mothers 2 and 3 and babies 2 and 3. Maternal serum concentrations were measured at 2 time points after the first infusion postpartum; the serum level of baby 2 was measured before and at 2 points after the first infusion postpartum; for baby 3, it was available only at 1 time point after the first infusion. ^aBelow the detection limit; ^bSample stability issues.