Skip to main content

Microbes from Birth Canal May Affect Stress Levels of Offspring

July 16, 2018

Tracy Bale, PhD

Researchers Unravel Key Mechanism for Transfer of Stress Exposure

Researchers have long known that stress during pregnancy may be transferred from the mother to her offspring. Many studies have shown that this stress can have long-lasting impacts on the physical and emotional health of the offspring. However, the mechanisms of this transfer have remained mysterious. A new study has unraveled one possible way in which these effects move from mother to child.

During birth, bacteria in the mother’s vaginal canal coat the infant; these microbes are transferred to its gut. This process may play an important role in transferring stress from mother to infant. Tracy Bale, PhD, a professor in the University of Maryland School of Medicine (UMSOM) department of pharmacology and director of the UMSOM Center for Epigenetic Research in Child Health and Brain Development, along with several colleagues, exposed newborn mice to microbes from female mice that had been stressed. She found that this transfer also transmitted some of the effects of stress to the newborns. These changes resemble those seen in the male offspring of mothers that were stressed during pregnancy.

The study, which was published July 9 in the journal Nature Neuroscience, may lead to a better understanding of the way in which maternal trauma, such as stress, affects the brain development of her offspring.

Microbes present in vaginal fluid colonize the gut of newborns when they pass through the birth canal. The composition of this gut microbiome influences the brain’s development and how it its responds to stress later in life. In mice, prenatal stress is known to alter the vaginal microbiota and affect male offspring’s brain function after birth. But it has not been clear how these brain changes are caused by the altered microbiota.

Dr. Bale transplanted microbes from the vaginal fluid of either stressed or unstressed pregnant mice into both prenatally stressed and unstressed male offspring immediately after these babies were born by C-section, so were not exposed to the mother’s vaginal microbes. She found that the pups exposed to both stress in the womb and microbiota from stressed mothers had decreased body weights and growth and increased stress hormone levels as adults. They found that these effects could be partially reproduced in unstressed, newborn male offspring by transferring vaginal microbes from stressed mothers. Microbes from unstressed mothers, however, did not rescue the effects of stress in the womb.

These findings indicate that stress during pregnancy affects mice both directly during their gestation, in part, the team found by developmental changes to the fetal immune system, and indirectly by altering the vaginal microbiota of the mother. In humans, maternal stress during pregnancy is a risk factor for psychiatric disorders in offspring, but it remains unclear whether this risk is also influenced by the vaginal microbiota.

“These results are very intriguing,” Dr. Bale said. “It is definitely worth investigating whether the effects we found in mice also hold true in humans.”

Dr. Bale has focused much of her research on the links between stress and subsequent risk for neurodevelopmental disorders, including autism and schizophrenia. Her previous work on the placenta has found novel sex differences that may predict increased prenatal risk for disease in males.

She has previously found that, in mice, a father’s stress can affect the brain development of offspring. This stress can alter the father’s sperm, which can alter the brain development of the child. Dr. Bale has also found that male mice experiencing chronic mild stress have offspring with a reduced hormonal response to stress; this response has been linked to some neuropsychiatric disorders, including PTSD. This suggests that even mild environmental challenges can have a significant effect on the health of offspring.

“Increasingly we are realizing that the microbiome has wide-ranging effects on the human host,”said E. Albert Reece, MD, PhD, MBA, Executive Vice President for Medical Affairs at the University of Maryland, Baltimore, and the John Z. and Akiko K. Bowers Distinguished Professor and Dean, University of Maryland School of Medicine. “These intriguing findings indicate that the microbes that we harbor may play a crucial role in transmitting the effects of stress to offspring.”

About the University of Maryland School of Medicine

Commemorating its 210th Anniversary, the University of Maryland School of Medicine was chartered in 1807 as the first public medical school in the United States. It continues today as one of the fastest growing, top-tier biomedical research enterprises in the world -- with 43 academic departments, centers, institutes, and programs; and a faculty of more than 3,000 physicians, scientists, and allied health professionals, including members of the National Academy of Medicine and the National Academy of Sciences, and a distinguished recipient of the Albert E. Lasker Award in Medical Research. With an operating budget of more than $1 billion, the School of Medicine works closely in partnership with the University of Maryland Medical Center and Medical System to provide research-intensive, academic and clinically-based care for more than 1.2 million patients each year. The School has over 2,500 students, residents, and fellows, and more than $500 million in extramural funding, with most of its academic departments highly ranked among all medical schools in the nation in research funding. As one of the seven professional schools that make up the University of Maryland Baltimore campus, the School of Medicine has a total workforce of nearly 7,000 individuals. The combined School and Medical System (“University of Maryland Medicine”) has an annual budget of nearly $6 billion and an economic impact in excess of $15 billion on the state and local community. The School of Medicine faculty, which ranks as the 8th highest among public medical schools in research productivity, is an innovator in translational medicine, with 600 active patents and 24 start-up companies. The School works locally, nationally, and globally, with research and treatment facilities in 36 countries around the world. Visit medschool.umaryland.edu/

Contact

Office of Public Affairs
655 West Baltimore Street
Bressler Research Building 14-002
Baltimore, Maryland 21201-1559

Contact Media Relations
(410) 706-5260

Related stories

    Tuesday, April 25, 2023

    Immune System Sculpts Rat Brains During Development

    Researchers have established that biological sex plays a role in determining an individual’s risk of brain disorders. For example, boys are more likely to be diagnosed with behavioral conditions like autism or attention deficit disorder, whereas women are more likely to suffer from anxiety disorders, depression, or migraines. However, experts do not fully understand how sex contributes to brain development, particularly in the context of these diseases. They think, in part, it may have something to do with the differing sizes of certain brain regions.


    Thursday, January 27, 2022

    Microbiome of Mother’s Vagina May Affect Infant Mortality Risk and Baby’s Development

    A new study in mice from University of Maryland School of Medicine researchers showed that an unhealthy vaginal microbiome in pregnant mothers in combination with an unhealthy diet contributed to increased pup deaths and altered development in the surviving babies.


    Tuesday, June 08, 2021

    IN MEMORIAM: UM School of Medicine Biomedical Research Pioneer and Pharmacology Professor, Laure Aurelian, PhD

    The Department of Pharmacology at the University of Maryland School of Medicine (UMSOM) is saddened to announce the passing of Laure Aurelian, PhD, Professor Emerita of Pharmacology. She was the first woman to receive a PhD from the Johns Hopkins University School of Medicine and was a pioneer who opened doors for many women to pursue research careers in biomedical science. She was also among the first women to receive independent funding from the National Institutes of Health, receiving her first R01 award in 1970.


    Wednesday, May 05, 2021

    Three Leading UMSOM Faculty Named Among Maryland's Top 100 Women

    The Maryland Daily Record has named three leading faculty members at the University of Maryland School of Medicine to its 2021 listing of Maryland’s Top 100 Women. The three-- Tracy L. Bale, PhD, Professor of Pharmacology; Kimberly Lumpkins, MD, MBA, Associate Professor of Surgery; and Jill RachBeisel, MD, the Dr. Irving J. Taylor Professor and Chair of Psychiatry—were chosen for their “outstanding achievements demonstrated through professional accomplishments, community leadership and mentoring,” according to the publication.


    Wednesday, October 21, 2020

    UM School of Medicine Postdoctoral Fellow Awarded Prestigious AAAS Science and Technology Policy Fellowship

    Ryan Richardson, PhD, Postdoctoral Fellow, Department of Pharmacology, at the University of Maryland School of Medicine (UMSOM) was awarded a highly prestigious American Association for the Advancement of Science (AAAS) Science & Technology Policy Fellowship (STPF), placing him at the National Institutes of Health (NIH)’s Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative for a year.


    Thursday, September 19, 2019

    The Reading on the Brain Program Teaches Baltimore City Elementary Students About the Brain-Building Power of Reading

    A giant mural with images depicting reading and the brain was unveiled during a ribbon cutting ceremony at Baltimore's Callaway Elementary School. It was part of Reading on the Brain, a University of Maryland School of Medicine (UMSOM) program to teach young students about the importance of reading and how reading can stimulate brain development and inspire future success.


    Friday, September 06, 2019

    UMSOM's Dr. Margaret McCarthy Awarded Indiana University's Gill Transformative Investigator Award for Neuroscience Research

    Indiana University’s Gill Center for Biomolecular Science has given Margaret McCarthy, PhD, The James & Carolyn Frenkil Endowed Dean’s Professor and Chair of the Department of Pharmacology at the University of Maryland School of Medicine (UMSOM), The Gill Center for Biomolecular Science 2019 Gill Transformative Investigator Award.


    Monday, April 29, 2019

    UMSOM’s Reading on the Brain Program Teaches Baltimore City Elementary Students About the Brain-Building Power of Reading

    Acting Baltimore City Mayor Jack Young joined 4th and 5th grade students at Callaway Elementary School to help paint a mural about the brain. It was all part of Reading on the Brain, a University of Maryland School of Medicine (UMSOM) program to teach young students about the importance of reading and how reading can stimulate brain development and inspire future success. Tracy Bale, PhD, is leading the pilot program, which also emphasizes science and helps children to understand how the brain works.


    Thursday, March 28, 2019

    Allergic Reactions Play Role in Sexual Behavior Development in Unborn Males and Females, UMSOM Research Shows

    Researchers at the University of Maryland School of Medicine and colleagues at Ohio State University have discovered that allergic reactions trigger changes in brain behavior development in unborn males and females. This latest brain development discovery will ultimately help researchers better understand how neurological conditions can differ between men and women.


    Friday, March 01, 2019

    UMSOM Researchers Discover Clues to Brain Differences Between Males and Females

    Researchers at the University of Maryland School of Medicine have discovered a mechanism for how androgens -- male sex steroids -- sculpt brain development. The research, conducted by Margaret M. McCarthy, Ph.D., Professor of Pharmacology and Chair of the Department of Pharmacology, could ultimately help researchers understand behavioral development differences between males and females.


    Tuesday, September 11, 2018

    New Study Finds Unexpected Link Between Immune Cells and Male/Female Differences

    Researchers at the University of Maryland School of Medicine (UMSOM) have made a surprising discovery: during fetal development, a particular immune cell seems to play a key role in determining the male or female characteristics of the brain.


    Wednesday, July 11, 2018

    Scientists Identify Mechanism That May Explain Why Males Have a Higher Risk for Neurodevelopmental Disorders

    Researchers have recently begun to realize that biological sex plays a key role in disease risk. Sex differences play a role in hypertension, diabetes, arthritis – and in many neurological and psychiatric disorders. Depression and anxiety affect females more, while neurodevelopmental disorders, including autism spectrum disorders, early onset schizophrenia, and attention deficit hyperactivity, affect more males. Males are also more sensitive to issues during pregnancy, such as maternal stress, maternal infection and exposure to drugs.


    Friday, June 15, 2018

    Acting Chairs Appointed for Pharmacology and Physical Therapy Departments During Chair Sabbaticals

    University of Maryland School of Medicine (UMSOM) Dean E. Albert Reece, MD, PhD, MBA, announced today that two department chairs, Margaret McCarthy, PhD, Professor and Chair, Department of Pharmacology, and Mark Rogers, PhD, PT, FAPTA, the George R. Hepburn Dynasplint Professor and Chair, Department of Physical Therapy and Rehabilitation Science (PTRS), will be taking sabbatical leave during the 2019 fiscal year. In making the announcement, Dean Reece noted that acting chairs have been named to provide leadership in these two departments during this period.


    Thursday, May 03, 2018

    Renowned Journalist Nicholas Kristof Speaks on Justice and Society

    Renowned New York Times journalist Nicholas Kristof will speak on May 3 at the Peabody Library in Baltimore on the need to build a fairer society.


    Thursday, March 01, 2018

    Increased Stress on Fathers Leads to Brain Development Changes in Offspring

    New research in mice has found that a father’s stress affects the brain development of his offspring. This stress changes the father’s sperm, which can then alter the brain development of the child. This new research provides a much better understanding of the key role that fathers play in the brain development of offspring.