Clinical Research Directory

Inclusion Criteria: * 1\. Lactating female participants 18 years of age or older treated with YORVIPATH as part of their usual medical care and who have chosen to breastfeed. Note: The participant must have been taking YORVIPATH for a minimum of 14 days prior to sample collection. * 2\. The major source of infant nutrition must be breast milk (Note: Only one supplemental bottle of no more than up to 8 oz of formula per day will be allowed during the 14 days before start of the study). * 3\. Daily dose of YORVIPATH administered within the last 14 days has been stable. * 4\. Participants recruited from other sources must enroll in the Pregnancy Registry before being allowed to participate in the Lactation Study. * 5\. Written consent or eConsent obtained. Exclusion Criteria: * 1\. Presence of any medical condition that, in the opinion of the investigator, may impair the ability to breastfeed during this study, including but not limited to mastitis and nipple malformation