Inclusion Criteria:  Women who are lactating, or who are admitted and/or consented for cesarean delivery and planning to breastfeed postpartum, AND are receiving at least one DOI per standard of care from their provider or through self-care (for over-the-counter medications). Mothers who are at least 18 years of age  Exclusion Criteria:  Induced lactation Currently taking medication or supplements to increase milk production Diagnosis of any significant chronic medical condition including (but not limited to) hepatitis, HIV, heart failure, liver or renal failure, or malabsorption conditions (e.g. celiac disease or inflammatory bowel disease) known to alter PK of DOI, unless the DOI is the indicated treatment for that disease Alcohol use within 72 hours of study visit or planned PK blood draws Illicit substance, other than THC, use within 1 week of study visit or planned PK blood draws