One in 27 first-time mothers reported noncommodified peer-to-peer milk sharing via online or personal networks outside of accredited pasteurized donor human milk (PDHM) banks, a large study in a diverse US population found.

Pediatric clinicians should be aware of this practice and advise mothers about risk-reducing strategies, said Jill R. Demirci, PhD, RN, director of the Maternal/Perinatal and Reproductive Health Research Hub at the School of Nursing, University of Pittsburgh, Pittsburgh, and colleagues. The findings appeared in JAMA Network Open.

“Clinicians should recognize that informal milk sharing happens across many populations of US parents and provide nonjudgmental guidance on how to mitigate risk, such as safe handling and storage,” co-author Lori Uscher-Pines, PhD, a senior policy researcher at RAND Corporation in Arlington, Virginia, told Medscape Medical News. The results highlight persistent gaps in breastfeeding support and access to PDHM, especially for low-income families.

“Expanding equitable access to professional lactation support and donor milk could reduce interest in informal milk sharing,” said Uscher-Pines.

PDHM is rarely accessible for healthy infants because it is prioritized for preterm and medically fragile newborns and is also expensive.

“Our studies have demonstrated that the populations served by milk banks and community milk sharing are different,” said Aunchalee E.L. Palmquist, PhD, MA, an associate professor of the practice of global health and cultural anthropology at Global Health Institute, Duke University, Durham, North Carolina, and not involved in the study. “The current US milk-banking system would need to be redesigned to accommodate community milk sharing, and that [would] take funds and investment and considerable expansion.”

Diverse Study Population

We felt this study was important because shared milk is an understudied and probably underreported phenomenon with the potential to influence both the mother’s and baby’s health, Demirci told Medscape Medical News. While it’s unclear whether this practice is increasing, the study found a 3.7% rate in the US.

The study used data from a 2024 randomized clinical trial of telelactation support that recruited nulliparous women of 33-37 weeks’ gestation across 39 states from July to December 2022.

Data were available for 1909 of 2108 enrolled participants with a mean maternal age of 29.6 years. The demographically diverse cohort included 32% Black individuals, 3% American Indians or Alaska Native populations, 5.1% Asians, and 51.5% White individuals.

At 24 weeks postpartum,180 participants (9.4%) reported feeding their infants donor or shared milk. The most common source was PDHM (6.1%), followed by shared milk (3.7%), including milk sourced from friends or family (2.7%), milk-sharing networks (0.9%), and other sources (0.3%). Ten mothers (0.5%) used both PDHM and shared milk.

Previously, a 2013 survey had found that 29% of mothers (majority North American) with low milk supply used shared milk, a practice likely facilitated by the expansion of social media.

“From prior research, we know that women use shared milk for many different and complex reasons, often because of factors like low milk volume or situations like adoption, surrogacy, or cancer treatment,” Demirci said. “But there are other reasons that differ by culture and population.” 

Risks

The primary risks of milk sharing relate to medications, substances such as nicotine, alcohol, or illegal drugs, or maternal health conditions that could be transmitted through milk, as well as unsanitary expression practices or improper storage.

“However, it’s important to note that informal milk sharing that is noncommercial or noncommodified has not been linked to significant documented risk to date,” Demirci said. “One likely reason is that donors are typically feeding the same milk to their own babies and are therefore motivated to use safe expression and storage practices.” And because these exchanges are not financially driven, there is no incentive to dilute, tamper with, or misrepresent the milk, she said.

Participants in the current study who used either PDHM or shared milk were more likely to feel unsuccessful at breastfeeding and used infant formula at rates comparable with users not using donor milk, despite assumptions that donor milk reduces formula use. That underscores the crucial need for maternal lactation support even when alternatives are available, Demirci stressed. While milk-sharing families are typically attuned to the benefits of breastfeeding and the risks of milk sharing, they do not always qualify for PDHM from accredited donor banks.

Safety Recommendations

Organizations such as the Academy of Breastfeeding Medicine outline specific measures to ensure the safety of community-shared milk — measures that emerged from the formula shortage during the COVID pandemic and factory contamination crises.

These include ascertaining donors’ medical and social history, current medications, and substance use. Also important is determining how hygienically the milk was expressed and stored, including how long it was kept at room temperature or frozen and then defrosted.

Improving parent and healthcare provider communication through education would empower parents and help keep babies healthy, Palmquist said. “The first step is understanding the evidence and critically evaluating personal biases regarding safety and risk and preventing the stigmatization that is a barrier to honest and transparent parent-provider communication.”

This work was supported by the National Institutes of Health, National Institute of Nursing Research. Demirci reported serving as an unpaid board member at the Mid-Atlantic Mothers’ Milk Bank. No other competing interests were disclosed. Palmquist had no conflicts of interest.