2.1B Prenatal brain development
The information on this page draws from the SECD – Prenatal Development Module. Please see that module for more information.
NOTE: The section on DOHaD has moved to BD 2.1 A
Healthy childhood brain development is influenced by the preconception health of the parents, and a great deal of brain development occurs prenatally. Prenatal brain development is the foundation for the long-term health and well-being of each child. Think back to the tree analogy used on page 1 of this module – just as healthy trees require the right moisture, sunlight, temperature and soil conditions to grow, children depend on nurturing interactions, play and stimulation, and rich language environments and experiences to grow up as healthy individuals. In the context of prenatal brain development, both the biological contributions of the parents (including their preconception health) and the womb environment play important roles in how the fetal brain develops. As discussed on p. 2.1A, gene-environment interactions have a significant influence on fetal development while the brain is forming prenatally, as physiological adaptations or disruptions in the developmental trajectory occur based on the womb environment. This page will explore the following questions:
- How does the brain develop during the prenatal period?
- What factors alter the womb environment and affect prenatal brain development?
- How is current research expanding our knowledge of prenatal brain development?
Development of the brain in the prenatal period
The prenatal period is a time of great sensitivity for the brain. Throughout the months of pregnancy, the brain, spinal cord and nervous system gradually form. The next two readings describe how the fetal brain develops. The first is an overview of prenatal brain growth from the Zero to Three website and the second is a more detailed look at how the brain changes during pregnancy, in the newborn period, and beyond.
More in depth information about how the brain develops is explained on The Brain from Top to Bottom website, starting with “How the Nervous System Begins” immediately followed by “How the Major Subdivisions of the Brain are Formed.”
In the next video, Sir Peter Gluckman, who served as the inaugural chief science advisor to the Prime Minister of New Zealand, discusses how the maternal and womb environment influence fetal development. Learn why maternal health during pregnancy is so important to the long-term health of the child.
In the next video, Dr. Christine Ateah, vice-dean in the Faculty of Health Sciences and professor in the College of Nursing at the University of Manitoba, explains how parents can promote healthy environments that support the overall development of their baby prenatally.
Longitudinal studies can examine how prenatal environments influence long-term health outcomes. In the following video, Dr. Stephen Lye, professor in the Departments of Obstetrics & Gynaecology, Physiology and Medicine at the University of Toronto as well as executive director of the Alliance for Human Development, Lunenfeld-Tanenbaum Research Institute, describes the Ontario Birth Study and Target Kids cohort studies. He explains the implications of these studies for current and future prenatal research.
A study is underway using this longitudinal data to understand how maternal seasonal affective disorder influences placental production of serotonin, which is an important hormone in forming brain circuitry during early pregnancy (Ontario Birth Study, 2017). This is one example of how studies can gather data prenatally to learn more about the association between prenatal brain development and long-term outcomes for children.
Environment and the brain in the prenatal period
The maternal environment influences prenatal brain development through many factors such as the social and structural environment of the family, maternal lifestyle and nutritional status. In the slideshow below, Dr. Hardy, from Western University, describes studies conducted with rats who are fed low protein diets, that have shown a lower liver to brain ratio than normal and explains why that occurred. Click on the audio icons at the bottom of each slide, to hear Dr. Hardy explain what his animal research is revealing about these effects and the mechanisms through which this type of fetal programming may occur.
Dr. Hardy’s research has indicated that the fetus will prioritize using the resources transferred through the placenta to maximize brain development in adverse nutritional environments. The fetal brain has many nutritional needs, and Dr. Lye explains more about the fetal brain’s nutritional requirements in the next video. Among other requirements, Lye discusses lipids, which are substances such as fatty acids, triglycerides, oils and waxes. In the context of cell development, lipids are important in storing energy, they help to form the outer layer of cells, and are involved in the formation of some hormones. Additionally, Lye talks about stimulation and protection from abuse, neglect, and violence – factors that come more into play following birth.
As Lye explains in the above video, by the time a baby is born, the brain has formed billions of neurons and is ready to continue being shaped by the stimulation and experiences that occur after birth. Learn more about important environmental considerations for promoting healthy prenatal brain development in the following readings. The first is from the Centers for Disease Control and Prevention and the second is from the National Scientific Council on the Developing Child.
Earlier on this page, Ateah mentions teratogens as she discusses factors that can affect fetal development. Teratogens are substances or factors that can cause abnormalities in fetal development, such as birth defects (The Gale Encyclopedia of Medicine, 2008). Common known teratogens include alcohol, and certain medications, drugs, chemicals and some maternal infections and viruses. Nearly half of pregnancies in Canada are unintended (The Society of Obstetricians and Gynecologists of Canada, n.d.). Given that a great deal of fetal brain development occurs in the first three months of pregnancy, many negative effects from teratogens potentially could occur before the parents are aware of the pregnancy.
The teratogenic effects of alcohol exposure can have a very harmful effect on fetal development. Fetal Alcohol Spectrum Disorder (FASD) is an example of a condition that develops due to the ingestion of alcohol during pregnancy. Depending on the amount and timing of alcohol exposure during the prenatal period, a wide range of long-term effects can develop. These can range from problems with attention, memory, learning, behaviour and social skills to severe cognitive impairment and specific facial and cranial characteristics associated with FASD. Dr. Joanne Weinberg is a professor emerita and distinguished scholar in the Faculty of Medicine at the University of British Columbia. She describes her research with animal models in establishing alcohol as a teratogen during pregnancy and the advantages of using animal models in research.
Weinberg further describes research demonstrating how prenatal exposure to alcohol alters gene expression in the brain, causes changes to stress and immune responses, and affects the way that cells work and communicate with each other in the brain.
Learn more about how the environment and experiences shape the fetal brain in the following reading from the Center on the Developing Child at Harvard University.
The above reading explains that nurturing, stimulating experiences lead to epigenetic modifications that create the foundation for cognitive development later in life. Research continues to explore how babies begin to form memories for sound during the prenatal period. On p. 2.4 in this module, Dr. Ron Barr describes an interesting experiment used to establish that after birth, babies can remember sounds they experienced prenatally. Dr. Janet Werker is research chair in the Department of Psychology at the University of British Columbia. Listen as she explains more about her research, which has identified that babies remember prenatal language exposure and show a preference for familiar language patterns after they are born.
Consider how knowledge about this information may influence the opportunities for language exposure that parents provide to their babies while in the womb.
Dr. Stephen Matthews, professor of Physiology, Obstetrics and Gynaecology and Medicine at the University of Toronto, explains that while the development of the brain is dependent on the environment, different areas of the fetal brain also have specific windows of sensitivity (as discussed on p. 1.2 of this module).
How could you use this information about windows of sensitivity, and the influence of prenatal environments on long-term outcomes for children, in your work?”
What further research questions would you ask to learn more about this topic?
Family and community level influences on prenatal brain development
The idea that adversity within families, particularly maternal prenatal stress, can influence fetal development and long-term health and well-being has been another important focus of recent research. Studies from animal research show that high levels of maternal cortisol may negatively affect fetal brain development and may alter the fetal stress response. Similarly, in humans, prenatal stress or adversity has been shown to be associated with altered stress activity after birth, and negative effects on child development (Lupien, McEwen, Gunnar & Heim, 2009; p. 434-436), including behavioural and emotional processing and certain mental illnesses (Glover & Capron, 2017). On the other hand, research also demonstrates how nurturing care and stimulation can protect children from the effects of stress. Stronger maternal-fetal relationships have been associated with more sensitive and nurturing interactions between mothers and children after they are born (Foley and Hughes, 2018), enhancing the environment for prenatal and postnatal brain development. Supportive social and physical environments for families act as buffers to minimize maternal and family stressors and enhance well-being during pregnancy and beyond. According to the Government of Canada (n.d.), 12 main determinants affect the health of Canadians. Examples of how these influences may potentially affect parental health are shown in the image below titled “Maternal Health Influences”. This topic is explored in more depth on p. 1.2 of the SECD – Prenatal Development module.
In the next videos, Dr. Matthews explains how maternal adversity and elevated cortisol levels affect fetal outcomes. Cortisol is a glucocorticoid hormone that helps the body to increase energy levels and maximize cardiovascular efficiency during the body’s stress response. Glucocorticoids are steroid hormones that help the body to respond to stress and deal with environmental change (Brain Facts, 2012). Matthews explains how the study of fetal exposure to glucocorticoids, specifically cortisol, is telling us about fetal programming after birth.
Earlier on this page, Sir Gluckman described how the placenta acts as a buffer between the maternal and fetal environment. A healthy placenta will transfer the nutrients, oxygen and hormones needed for optimal fetal development, remove the fetus’ waste and gases, produce pregnancy hormones, and filter some harmful substances to prevent them from reaching the fetus. In the video below, Dr. Hardy describes his lab research into the relationship in cell cultures between low oxygen and impairment of a placental enzyme and hormone barrier that is responsible for preventing a significant amount of maternal cortisol from reaching the fetus.
Dr. Chris Kuzawa is a professor and faculty fellow at the Institute for Policy Research in the Department of Anthropology at Northwestern University. In the next video he describes research in this field that uses both measures of prenatal stress and deprivation, and measurement of cortisol levels in babies postnatally during a stressful event, to learn about how prenatal stress may be associated with how babies experience and respond to stress after they are born.
Through laboratory research in animals, the interaction of glucocorticoids with the fetal epigenome has been implicated in changes to fetal stress responses. This understanding has implications for lifelong cardiometabolic risk and programming of increased risks for other diseases in humans. Listen to Matthews explain this area of research.
The normal course of fetal brain maturation and development may be altered not only in situations where there is an acute maternal stress response (e.g., in situations where there is a death of a loved one), but also when a neuropsychiatric disorder, such as depression, exists in the mother (Ross & Desai, 2012, p. 91). According to the Public Health Agency of Canada’s fact sheet Pregnancy and Women’s Mental Health in Canada: Results from the Canadian Maternity Experiences Survey (2014), 15.5% of Canadian women surveyed reported having had a depression diagnosis or treatment with anti-depressants prior to becoming pregnant. In the following videos, Werker describes a study that compared the babies of mothers who were not depressed with the babies of depressed mothers who took anti-depressant medication (called serotonin reuptake inhibitors, or SRIs) and babies of mothers who did not take medication, to look at whether the infant brain’s perception of language was affected.
Werker’s research has identified differences in the developmental trajectory of language for infants of mothers exposed to anti-depressants in utero. Given the prevalence of maternal depression prior to pregnancy, promoting mental health preconception is advisable. Werker goes on to explain the significance of her work and areas for future research.
As Dr. Werker states, depression and adverse circumstances during pregnancy occur regularly. Her work attempts to discover specific mechanisms that affect language development during adverse circumstances for each individual. Consider the reflective questions below regarding how a healthy pregnancy is influenced not only at the individual and family level but also by community and societal environments.
Think about your neighbourhood, workplace and community as environmental settings with the potential to alter how genes are expressed, how parents experience stress, and how each child’s brain grows, develops and learns prenatally. How can each of these settings contribute to healthy outcomes for children and families?
If you could make two recommendations to improve these environments to support healthy brain development prenatally, what would they be and why?
Try the next quiz to review information on prenatal brain development.
