BreastfeedingMedMilkNCT07346716
Medicines in Breast Milk and Estimated Infant Exposure
An observational study of Breastfeeding and Medication Safety, run by University Hospital Bispebjerg and Frederiksberg at 3 sites in Denmark.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 years and older, women onlyHealthy volunteers can take part
- Conditions the study is for
- Breastfeeding, Medication Safety, Lactation
- What is being tested?
- Prescription Drugs
- How many people
- 250 participants
- Where
- 3 sitesDenmark
- Study dates
- 20 Dec 2024to Jan 2030
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- Women only
- Healthy volunteers accepted
- Adult, Older adult
Study population: Participants will be lactating women recruited through obstetric, neonatal, and psychiatric departments, public health visiting nurses, and counselling services across Denmark. Recruitment will be coordinated by the Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, Copenhagen. The study primarily targets women using prescription and over-the-counter medicines during breastfeeding and aims to represent real-world exposure patterns across all Danish regions.
Who may be able to join
- 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
Who cannot join
- Current pregnancy during sample collection
- Known and clinically significant pharmacokinetic drug-drug interactions at the time of sampling
Trial locations and contacts
3 sites in 1 country. Contact the study team or a site near you to ask about taking part.
Jon Traerup Andersen, Professor, MD, PhD contact
Denmark3 sites, 3 recruiting
- Recruiting
Department of Clinical Pharmacology
Copenhagen
Ditte Resendal Gotfredsen, MD, +4521472051, ditte.resendal.gotfredsen@regionh.dk
Jon Traerup Andersen, Professor, MD, PhD, jon.thor.traerup.andersen@regionh.dk
- Recruiting
Mental health services, Capital Region of Denmark
Copenhagen
- Recruiting
Department of Obstetrics and Gynecology, Herlev Hospital
Herlev
About this study
Official title: Medication Concentrations in Human Milk (MedMilk) and Potential Adverse Effects in Breastfed Infants: an Exploratory Clinical Study
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
Read the 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.
- Conditions
- Breastfeeding, Medication Safety, Lactation, Drug Exposure Via Breast Milk, Pharmacokinetic Parameters
- Being tested
- Prescription Drugs
- Keywords
- breastfeeding, lactation, drug transfer into breast milk, medication safety
- Medical subject headings
- Breast Feeding
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Prescription DrugsDrug
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.
| Study group | Role | What they receive |
|---|---|---|
| Breastfeeding women on medication | Not described Receives: Drug: Prescription Drugs |
What is being measured
The primary outcome is the main question the study is designed to answer.
Drug concentrations in human milk
Quantification of drug concentrations in human milk, expressed in micrograms per millilitre (µg/mL). Milk samples are collected before and after the maternal dose within one dosing interval.
Measured: Within one dosing interval
Secondary outcomes (2)
Relative Infant Dose (RID)
Estimation of infant drug exposure, expressed as the relative infant dose (% of maternal weight-adjusted dose).
Measured: Within one dosing interval
Maternal-reported infant adverse effects
Maternal questionnaire on infant symptoms potentially related to drug exposure via breastfeeding.
Measured: At the time of inclusion. Montly follow-up for three months.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted16 Jan 2026
- Study start20 Dec 2024
- Primary completionJan 2028 (estimated)
- Study completionJan 2030 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for BreastfeedingStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 250 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University Hospital Bispebjerg and Frederiksberg
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Jón Þór Trærup Andersen, University Hospital Bispebjerg and Frederiksberg
- Investigators
- Jon Traerup Andersen, Professor, MD, PhD, Principal investigator, Department of Clinical Pharmacology, Bispbjeg and Frederiksberg Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07346716
- Sponsor's protocol ID
- H-23062687
- Acronym
- MedMilk
- Status last verified
- Jan 2026
- First submitted
- 8 Dec 2025
- Last updated
- 16 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes
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-2026-119958.
PubMed 42215272
Study at a glance
From the registry record, last updated by the sponsor on 16 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Medication Concentrations in Human Milk (MedMilk) and Potential Adverse Effects in Breastfed Infants: an Exploratory Clinical Study
- ClinicalTrials.gov ID
- NCT07346716
- Acronym / sponsor ID
- MedMilk / H-23062687
- Conditions
- Breastfeeding, Medication Safety, Lactation, Drug Exposure Via Breast Milk, Pharmacokinetic Parameters
- Keywords
- breastfeeding, lactation, drug transfer into breast milk, medication safety
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 250 participants (estimated)
- Lead sponsor
- University Hospital Bispebjerg and FrederiksbergUniversity, hospital or other
- Study start
- 20 Dec 2024 (actual)
- Primary completion
- Jan 2028 (estimated)
- Study completion
- Jan 2030 (estimated)
- First posted
- 16 Jan 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Breastfeeding women on medication | – | Drug: Prescription Drugs |
Who may qualify
- Ages
- 18 years and older
- Sex
- Female only
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
- Study population
- Participants will be lactating women recruited through obstetric, neonatal, and psychiatric departments, public health visiting nurses, and counselling services across Denmark. Recruitment will be coordinated by the Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, Copenhagen. The study primarily targets women using prescription and over-the-counter medicines during breastfeeding and aims to represent real-world exposure patterns across all Danish regions.
Key inclusion criteria (3 listed)
- 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
Key exclusion criteria (2 listed)
- Current pregnancy during sample collection
- Known and clinically significant pharmacokinetic drug-drug interactions at the time of sampling
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Prescription DrugsExposure 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. | Drug | Breastfeeding women on medication |
Primary outcome
Drug concentrations in human milk
Time frame: Within one dosing interval
Quantification of drug concentrations in human milk, expressed in micrograms per millilitre (µg/mL). Milk samples are collected before and after the maternal dose within one dosing interval.
2 secondary outcomes
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.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Jan 2026.
- Derived from this study: PubMed 42215272Resendal 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-2026-119958.
- Individual participant dataSharing planned: Yes
Related trials for Breastfeeding
RecruitingObservational study
Improving Nutrition for Babies Born by Caesarean Section
Breastfeeding Mothers of Legal Age, Their Babies Under 6 Months Old Born Vaginally
RecruitingPhase 4
A Study to Measure Mirikizumab Levels in Breast Milk of Lactating Participants Receiving Mirikizumab Therapeutically for an Approved Indication
Lactation, Inflammatory Bowel Disease
Enrolling by invitation
Development and Implementation of a Breastfeeding Program for Post-Cesarean Section Women Based on the 5A Nursing Model
Breastfeeding Rates
RecruitingPhase 4
A Remotely Conducted Study to Assess Concentration of TREMFYA in Breast Milk of Lactating Women Who Are Receiving TREMFYA Therapeutically
Psoriasis, Colitis, Ulcerative
Not yet recruiting
The Effect of Music Play and Stress Ball Application on Placental Separation Time, Episious Pain and Breastfeeding Success
Primiparity (First-Time Mothers), Breastfeeding
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Jon Traerup Andersen, Professor, MD, PhD contact
Jon Traerup Andersen, Professor, MD, PhD principal investigator
Department of Clinical Pharmacology, Bispbjeg and Frederiksberg Hospital
3 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Breastfeeding and Medication Safety, run by University Hospital Bispebjerg and Frederiksberg at 3 sites in Denmark.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 2 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 16 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 sites in Denmark. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Ditte Resendal Gotfredsen, MD (+4521472051, ditte.resendal.gotfredsen@regionh.dk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Drug concentrations in human milk (time frame: Within one dosing interval). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07346716, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Jan 2026.