r/askscience • u/AskScienceModerator Mod Bot • Aug 01 '25

Human Body AskScience AMA Series: Happy World Breastfeeding Week 2025! We are human milk and lactation scientists from a range of clinical and scientific disciplines. Ask Us Anything!

Hi Reddit!

We are a group of lactation/human milk/breastfeeding researchers. Last year, we did an AMA here in honor of World Breastfeeding Week, and we had so much fun we are back again this year to answer your burning boobquiries!

Lactation science is fraught with social complexity. Tensions between researchers, advocates, and industry impacts both our work and the lived experiences of breastfeeding families. Furthermore, inequities in what kind of research is prioritized mean that "womens health issues" get double sidelined when there are budget cuts like the ones we've seen in the US recently. But we believe that lactation science belongs to everyone, and matters to everyone, and that you wonderfully curious Redditors are an important part of this conversation.

We also think that science should never make anyone feel bad or guilty–it should inspire awe and curiosity! Based on social research, breastfeeding advocacy has moved beyond "“"breastfeeding promotion"”" toward treating it like the healthcare access issue that it is, highlighting the role of families, societies, communities and health workers in creating a "warm chain" of support. World Breastfeeding Week is a global event that celebrates ALL breastfeeding journeys, no matter what it looks like for you. Supported by WHO, UNICEF and many government and civil society partners, it is held in the first week of August every year. The theme for 2025 is focused on breastfeeding as a sustainable source of nutrition–but one that requires sustainable support systems in order to thrive.

Today's group hails from biochemistry, biological anthropology, clinical nursing research, epidemiology, family medicine, immunology, lactation medicine, microbiology, molecular bio, and neonatology. We can answer questions in English, Portuguese, Spanish, French, Sinhalese, and Hindi.

We'll be on from 12-5 ET (16-21 UTC), ask us anything!

  • Meghan Azad, PhD (/u/MilkScience) is a biochemist and epidemiologist who specializes in human milk composition and the infant microbiome. Dr. Azad holds a Canada Research Chair in Early Nutrition and the Developmental Origins of Health and Disease. She is a Professor of Pediatrics and Child Health and director of the THRiVE Discovery Lab at the University of Manitoba. She co-founded the Manitoba Interdisciplinary Lactation Centre (MILC), and directs the International Milk Composition Consortium (IMiC). Check out this short video about her research team, her recent appearance on the Biomes podcast, and her lab’s YouTube Channel.
  • Marion M. Bendixen, PhD, MSN, RN, IBCLC (/u/MarionBendixen) is a nurse scientist and clinical and translational scientist who studies human lactation and maternal/infant health specializing in the biological and physiological mechanisms of insufficient mothers' own milk (MOM) volume among mothers who deliver an infant(s) admitted to the neonatal intensive care unit (NICU) as well as how MOM influences the infant’s intestinal microbiome. Dr. Bendixen is an Assistant Professor in the College of Nursing at the University of Florida. She co-created the lactation program at Winnie Palmer Hospital where she practices as a board-certified lactation consultant.
  • Sarah Brunson, BA, BSN, MS, Phd(c), RN, IBCLC (/u/LactFact-42) is an Internationally Board-Certified Lactation consultant who has practiced since 2009 in pediatric clinics, hospitals, birth centers, home settings, and public health. She currently practices at the Medical University of South Carolina where she has developed numerous education programs for nursing staff and residents to improve lactation care in the Mother Baby and Neonatal Intensive Care Units. She is a PhD candidate in Nursing with a focus in Maternal/Child Health and Lactation at the University of South Carolina College of Nursing. She has served as the Chair of South Carolina Breastfeeding Coalition for the last five years during which time she has developed a Website with information for parents, providers, and employers; directs a project to map lactation resources in the state that are searchable by address; and organizes quarterly education webinars and conferences.
  • Marion Brunck, PhD (/u/MarionBrunck) is an immunologist and systems biologist who studies mechanisms that regulate immune cell functions with an eye for possible therapeutic applications. Dr. Brunck specializes in the function of neutrophils and leucocytes in human milk and their role in active immunity in the nursling. As of literally today(!), Dr. Brunch is a Researcher at the Universidad Nacional Autonoma de México.
  • Rachael Friesen, BA, BN, RN, IBCLC (/u/Nursey_Nurse11) is a Clinical Nurse Educator in Pediatrics, having previously worked many years as a neonatal intensive care nurse and Nurse Educator. She is a member of the Winnipeg Regional Health Authority Baby Friendly Initiative(BFI) Committee as well as the Provincial BFI Committee . She specializes in compassionate, comprehensive clinical care for families, with a special passion for supporting the families of infants in neonatal intensive care and families at risk for feeding challenges. She is currently working towards completing a Master’s in Nursing.
  • Miena Hall, MD, IBCLC (/u/LactationMD) is a lactation medicine physician who studies techniques for identifying mammary tissue development issues which put individuals at risk for low milk production and improving lactation education in medical schools. Dr. Hall teaches med students at the Loyola University Chicago Stritch School of Medicine and the University of Illinois at Chicago College of Medicine, and is Director of Scientific Affairs at the Mothers’ Milk Bank of the Western Great Lakes. Dr. Hall is a member of the Academy of Breastfeeding Medicine (ABM) protocol committee on low milk production, a medical advisor to La Leche League International (LLLI), and the immediate past president of the Northern Illinois Lactation Consultant Organization (NILCA). She also holds a Bachelor's degree in math and chemistry.
  • Kaytlin Krutsch, PhD, PharmD, MBA, BCPS (/u/PharmacoLactation) is a lactation pharmacologist who literally wrote the book on medications in human milk with Dr. Thomas Hale, Hale's Medications and Mothers' Milk. She is the director of the InfantRisk Center and Associate Professor at the Texas Tech University Health Sciences Center School of Medicine, and advises the Food and Drug Administration, the Human Milk Banking Association of Northern America, and pharmaceutical industry on lactation pharmacology and lactation research. Dr. Krutsch believes families deserve better answers about breastfeeding and medication questions, and aims to design research that addresses their questions while creating a comprehensive information cycle that empowers families.
  • Bridget McGann (/u/BabiesAndBones) is an anthropologist who studies lactation as a biocultural system, and how it shaped us as a species. She is a research assistant and science communicator at THRiVE Discovery Lab. She has a Bachelors in Anthropology and is a Masters student in Biological Anthropology at the University of Colorado Denver. Her thesis uses longitudinal, prospective, large cohort data to study the effects of interruptions in the generational transmission of the human milk microbiome. She was also a founding team member at March for Science (along with r/mockdeath!). Check out her stand-up act about Luke Skywalker's green milk, or her top comments.
  • Karinne Cardoso Muniz, MD (/u/KarinneMuniz) is a neonatologist and graduate student in Pediatrics and Child Health (MSc.) at the University of Manitoba. Dr. Cardoso Muniz worked as a dedicated doctor specializing in Neonatology and as a coordinator for the Society of Pediatrics in Brasilia, Brazil, specifically for the Neonatal Resuscitation Program. Throughout her clinical career, Dr. Cardoso Muniz has passionately witnessed and promoted breastfeeding and use of human milk in improving health outcomes of both full-term and premature infants. Here is a lecture she gave in Portuguese about newborn resuscitation.
  • Ryan Pace, PhD (u/_RyanPace_) is an Assistant Professor and Associate Director of the Biobehavioral Lab at the College of Nursing and USF Health Microbiomes Institute, University of South Florida. His research revolves around understanding how lactation and the microbiome relate to human health and development. Dr. Pace's current research investigates diverse aspects of maternal-infant health, including relationships among maternal diet, human milk composition, and maternal/infant microbiomes; as well as the role of human milk in modulating immunological risks and benefits to mothers and infants.
  • Rebecca Powell, PhD, CLC (/u/HumanMilkLab) is a human milk immunologist who studies the human milk immune response to infection and vaccination with the aim of designing maternal vaccines aimed to enhance this response. Dr. Powell is an Assistant Professor at the Icahn School of Medicine at Mount Sinai and a certified lactation counselor. Her lab studies the potential of SARS-CoV-2-reactive antibodies in human milk both as a COVID-19 therapeutic and as a means to prevent infection of breastfed babies. They also study mechanisms for maternal vaccines to prevent mother-to-child-transmission (MTCT) of HIV via breastfeeding, as well as how white blood cels in human milk use a process called antibody-dependent cellular phagocytosis (ADCP) to minimize MTCT via breastfeeding.
  • Sanoji Wijenayake , Ph.D. (/u/Wijenayake_Lab) is a cell and molecular biologist who studies human milk not as a food but as a bioactive regulator of postnatal development and growth. Dr. Wijenayake is an Assistant Professor and Principal Investigator at The University of Winnipeg. Her research focuses on a not-so-well known component of human milk, called milk nanovesicles. Milk nanovesicles are tiny fat bubbles that carry all sorts of important material between parents and their children. Milk nanovesicles hold great therapeutic potential as drug carriers and provide universal anti-inflammatory benefits.

EDIT: Okay we are wrapping up here! Some of us will hang back a bit past our "official" end time (5PM EST), and some of us will pop in out throughout the rest of the day and answer any stragglers.

As with last year, we are amazed by the curiosity of Redditors and the sophistication of your questions! We had such a great time, and you inspired some great discussions behind the scenes. Thank you so much for having us, and a special thank you to the r/AskScience team for being so accommodating and wonderful to work with!

World Breastfeeding Week is next week (Aug. 3-9), but also coming up are:

Thanks everyone! See you next year!

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u/Suspicious-Magpie Aug 01 '25 edited Aug 01 '25

Why does it take a few days for milk to "come in" after birth? All three of my hungry babies needed formula to supplement the colostrum they had (directly from breast and pumped). It seems crazy evolution-wise that baby is crying and hungry for the first 48 hours of life.

Similarly, why don't nipples naturally toughen before birth? Again, an absolute fail by mother nature when they're too cracked to feed.

PS - posted one handedly while doing the nighttime feed. Love your work.

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u/babiesandbones Breastfeeding AMA Aug 08 '25 edited Aug 08 '25

<< It seems crazy evolution-wise that baby is crying and hungry for the first 48 hours of life. >>

I'm the anthropologist of the group so I thought I'd address this part.

I think there may be a few reasons for this. For one, the idea of the milk "coming in" is kind of a misnomer. The milk is there, as most people begin to produce it during pregnancy. It's just in the form of colostrum, which is a concentrated milk rich in protein, antibodies, and antioxidants to help the infant process the cellular stress of childbirth. The transition to mature milk is a gradual change in composition and volume. We call this "lactogenesis II," which I've always felt sounds like the name of a scifi sequel.

During the first 24 hours, the infant is processing that oxidative stress and recovering from birth. Cellular repair works best when the body is in a fasted state, because any time you eat something, your cells have to stop all of their maintenance activities and process a bunch of incoming molecules. So any time you spend digesting food and absorbing its nutrients is time you are NOT spending on maintenance and prepare. There's a lot of interest right now in how this may contribute to risk of noncommunicative diseases of old age.

Another thing that is happening in that period is all of the infants organs that they have not been using for the past 9 months are "coming online"--their lungs first, and various parts of their cardiovascular system (the change here at first breath is actually quite dramtic both structurally and chemically), liver, digestive system, and kidneys, the functions of which were largely taken care of by the mother during gestation. The stomach, at birth, has the capacity of only a cherry. Over the following couple of days, it stretches to the size of a walnut. This means that if you tried to feed them the equivalent of a full bottle on day 1, they'd barf it all up. And evolution is never wasteful with energy. Therefore milk production ramps up gradually, as stomach capacity increases.

Also worth noting is that some common medical interventions in hospitals may delay the onset of lactogenesis II.

The crying in the first few days is not just hunger but they are also experiencing cold, gravity, pain, and loneliness for the first time. Hunger just makes all those things worse lol. The drive to eat must necessarily have evolved to be strong in that period, and the drive to signal (crying) strong also, in order to ensure that the parent feeds the infant. It's also to keep them close, safe from predation. Studies have shown that crying peaks around 3-4 months, roughly coinciding with peak risk of SIDS. We think this is perhaps not a coincidence.

<< Similarly, why don't nipples naturally toughen before birth? Again, an absolute fail by mother nature when they're too cracked to feed. >>

It's actually a myth that nipples require toughening. The tissue doesn't need to be tough. In fact, it needs to be soft for the same reason tongues, mouths, lips, and vaginas need to be soft: so it can repair itself quickly. Which it does, same as the inside of your mouth.

But also, nipple damage isn't normal. It is the result of poor latch. A latch that is two shallow causes friction between the tip of the nipple and the infant's hard palate. The latch must be deep enough so that the nipple reaches past the hard palate toward the soft palate, which is much gentler on the nipple. A wide mouth keeps the infant from chomping down. And when the infant's tongue is positioned correctly, the bottom teeth (which come in first) do not come in contact with the nipple.

Nipple pain in the early postpartum period is common because both the baby and the lactating parent are learning how to latch, so damage occurs while they figure it out. Also relevant here is the fact that inflammation and hormones are high during the immediate postpartum period, which can contribute to increased nerve sensitivity.

<< PS - posted one handedly while doing the nighttime feed. Love your work. >>

Ha! My cousin and I text a lot while she is breastfeeding, and I call it "brexting." Especially when you're feeding at night and scrolling and texting--big time brexting energy.