Medicines in Breast Milk and Estimated Infant Exposure
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Prescription Drugs.
- Who it may be relevant to
- Registry conditions: Breastfeeding, Medication Safety, Lactation, Drug Exposure Via Breast Milk. Basic parameters: from 18 years · Female.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Denmark
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Official title
Medication Concentrations in Human Milk (MedMilk) and Potential Adverse Effects in Breastfed Infants: an Exploratory Clinical Study
Overview
The MedMilk (Medication concentrations in human Milk) study investigates how selected medicines taken by breastfeeding women are transferred into human milk and whether this may affect the breastfed child. The study includes breastfeeding women who are already using prescription or over-the-counter medicines as part of their usual care. Participants provide samples of breast milk and urine and complete a questionnaire about maternal and infant health. The collected data will be used to quantify medicine concentrations in milk and estimate the relative infant dose. The study aims to contribute new data to support safer prescribing and more informed counselling during breastfeeding
Detailed description
The MedMilk (Medication concentrations in human Milk) study is a prospective, exploratory clinical study coordinated by the Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, Denmark. The study is observational in nature and involves no experimental drug administration. Participants are breastfeeding women using medicines as part of their routine treatment.
Each participant will provide four small breast milk samples (1-20 mL each) collected at different time points in relation to maternal drug intake, one urine sample, and questionnaire data on maternal and infant health, breastfeeding patterns, and any infant symptoms potentially related to drug exposure. Samples are stored at -80 °C in a dedicated research biobank until analysis.
Drug concentrations in milk and urine will primarily be quantified using solid Phase Extraction coupled with UPLC-MS/MS. Data will be analyzed descriptively, and relative infant doses (RID) will be calculated. For drugs with sufficient sampling density.
Results will add to the limited body of systematic data on drug transfer into human milk and help inform clinical decision-making regarding medication use during breastfeeding.
Interventions
- Drug Prescription Drugs
Exposure to prescription medicines taken by breastfeeding women during routine treatment. The study does not assign medications but observes drug transfer into human milk from exposures occurring as part of usual care.
Primary outcome measures
- Drug concentrations in human milk [Time frame: Within one dosing interval]
Secondary outcome measures (2)
- Relative Infant Dose (RID) [Time frame: Within one dosing interval]
- Maternal-reported infant adverse effects [Time frame: At the time of inclusion. Montly follow-up for three months.]
Eligibility criteria
Inclusion criteria
- Lactating women aged ≥18 years
- Current use of one or more prescription or over-the-counter (classified within the ATC system) drugs
- Able and willing to provide written informed consent
Exclusion criteria
- Current pregnancy during sample collection
- Known and clinically significant pharmacokinetic drug-drug interactions at the time of sampling
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: Yes
Study design
- Observational model
- Cohort
Study locations
Denmark · 3 centers
- Department of Clinical Pharmacology — Copenhagen
- Mental health services, Capital Region of Denmark — Copenhagen
- Department of Obstetrics and Gynecology, Herlev Hospital — Herlev
Publications
- Resendal Gotfredsen D, Heerfordt IM, Kahler Byskov P, Horwitz H, Gade C, Loekkegaard E, Friis-Hansen L, Bach Nielsen Fruekilde P, Cvetanovska E, Joergensen NR, Pedersen LH, Andersen JT. Medication concentrations in human milk and potential adverse effects in breastfed infants (MedMilk): a protocol for an observational clinical study. BMJ Open. 2026 May 29;16(5):e119958. doi: 10.1136/bmjopen-2026-1 PMID 42215272
Identifiers
NCT: NCT07346716 · H-23062687