Inclusion Criteria:

- Mother is registered with the PROMACTA Pregnancy Registry and meets all the
enrollment criteria defined in the PROMACTA Pregnancy Registry study (113327).

- Mother is continuing to take eltrombopag.

- Mother has received 7 consecutive eltrombopag doses prior to the milk sample
collection.

- Infant is 4 weeks to 26 weeks of age at the time of milk sampling.

- Exclusively breastfeeding mother-infant pair; either via breast or with expressed
milk from the mother.

- Mother is capable of giving written informed consent, which includes compliance with
the requirements and restrictions listed in the consent form.

Exclusion Criteria:

- Infant was born with complications that could impact ability to participate in this
study.

- Breastfeeding is not well established in the mother-infant pair (e.g., poor latching
of the infant or low milk supply).

- Infants who are supplemented with formula or are consuming solid foods.

- Unwillingness or inability of mother to follow the procedures outlined in the
protocol.

- Mother is mentally or legally incapacitated