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Key points
- Interactions in infancy "socially tune" babies’ brains, impacting mental health and future relationships.
- Vaginal birth alters the bodies and neurology of mother and newborn to aid reciprocal bonding.
- Cesarean section birth can thus impair the infant/mother bond and baby’s social development.
- However, techniques like skin-to-skin contact can improve outcomes.
This post is part 2 in a series. Read Part 1 here.
Vaginal birth initiates profound physiological, neurological, and behavioral changes in both mothers and infants. In addition to preparing the newborn for life outside the womb, it triggers new behaviors and reactions, such as infants seeking physical closeness, suckling, and crying when separated from their mothers. Mothers are also transformed, finding nursing and caring for her baby viscerally rewarding.
These interactions set in motion a process that profoundly impacts children’s emotional, social, physical, and cognitive development—and, therefore, their eventual capacity to thrive at school, at work, and in intimate relationships throughout life. The virtuous cycle of mutual bonding between mother and child is driven by something called “bio-behavioral synchrony.”
Bio-behavioral Synchrony: What It Is and Why It Matters
Synchrony is the coordination, moment to moment, of biology and behavior between partners during social contact. It is a full-body response that can be triggered by coordinated activity—a shared laugh or gaze, dancing, playing peekaboo. Synchrony aligns physiological processes, including heart rhythm, hormone release, and brain activity, which fuels bonding and induces feelings of euphoria, completion, oneness, and connection between mothers and their infants (a similar experience happens to adults during sex between loving partners).
When we try to connect with someone in this way but fail, we experience desynchrony and feel disappointed, lonely, hurt, rejected, and pessimistic. For example, when babies reach out to us with their eyes, mouths, or hands but we fail to acknowledge their cues, we are out of sync with them. This upsets them, as can be seen in this still face experiment.
Lack of bio-behavioral synchrony during nursing and early childcare can have negative consequences for mothers, babies, and their relationship. This 50-year-old research video is outmoded in its descriptions, but effectively illustrates varying degrees of synchronous and desychronous caregiving.
Where the babies receiving synchronous care are relaxed, affectionate, and gratified, those receiving desynchronous responses often become distressed. For them, the interaction is aversive rather than rewarding, which can impact their expectations for future intimate social interactions. Babies’ negative responses can fuel painful senses of inadequacy, guilt, or anger in mothers, which can undermine mutually satisfying interactions, and erode bonding.
The Lifelong Impact of Early Experiences
Babies who experience this kind of negative social tuning during infancy are more likely, as adults, to find pleasure in socially isolating behaviors like workaholism, internet and social media obsession, substance abuse, gambling, and fighting. Such children often have difficulty delaying gratification, managing stress, self-soothing, bouncing back when times are tough, regulating their emotions, and even sleeping well.
Ruth Feldman, Simms/Mann professor of social neuroscience and director of the Center for Developmental Social Neuroscience at Reichman University, with a joint appointment at Yale Child Study Center, has published hundreds of studies showing that human social development and one’s capacity for closeness, empathy, and intimacy is shaped by the presence and degree of bio-behavioral synchrony between mother and infant.
Failure to experience consistent bonding with primary caregivers during the first nine months of life can lead to lasting alterations in children’s brains, behavior, neuroendocrine reward systems, empathy, and even a fourfold increase in likelihood of serious psychiatric illness.
That is what a “sensitive” or “critical” period in development means. If the necessary experiences do not occur within a specific time frame, development is hampered, no matter what happens later. Just as a songbird chick that does not hear species-specific songs at the right time can never learn to sing them, humans deprived of physical contact and emotional bonding with caregivers in infancy struggle to become emotionally and socially adept adults. They may still be able to function well in society, but are more likely to experience challenges.
Mitigating the Consequences of C-Section or Premature Birth
Unfortunately, the physiological and neurological changes which support synchronous caregiving can be suppressed or disrupted by Cesarean section birth. Parallel problems arise with premature births, as the bio-behavioral triggers that facilitate caregiving are interrupted when the infant is kept in isolation, physically separated from the mother.
Newborns can suffer distress if separated from their mothers for even an hour, and in older infants, being separated from their mothers overnight during sleep training has been shown to disrupt mother/child synchrony in cortisol levels.
It is therefore unsurprising that some studies have shown links between C-section and preterm births and ADHD, depression, anxiety disorders, and mental illness—all of which have risen in correlation with C-section and preterm births.
While the processes behind these links haven’t been fully established, work by Feldman and others suggests that increased post-surgical pain for mothers and stress in both mother and infant may be components. Research presented at the 2022 Society for Neuroscience shows how environmental factors, like postnatal stress, deprivation, and physical pain diminish positive maternal brain changes and foster depression. These same factors have also been shown to disrupt infant development of reward circuits, reducing brain connectivity and white matter, as well as increasing infant anxiety and hypervigilance.
The good news is that measures like kangaroo care (“KC,” during which the naked infant is placed on the naked chest of the caregiver) and breastfeeding can facilitate the development and maintenance of synchronous bonding, regardless of delivery method.
Numerous studies by Feldman and others have repeatedly confirmed the long-term benefits of KC. Last November, the World Health Organization (WHO) updated its guidelines accordingly, recommending immediate post-birth KC care, including for low birth weight and premature infants. Skin-to-skin contact during the first hour after birth reduces infection and aids infant/caregiver bonding and breastfeeding. It also helps the mother’s body regulate the infant’s heart rate, body temperature, breathing, and sleep (infants’ bodies cannot yet regulate these systems independently). Ideally, stressed infants should have at least 17 hours of KC per day, but 8 hours is the minimum recommended during the first six months of life, according to the WHO.
Vaginal delivery gives infants the best start, but when that is not possible, this disadvantage can be overcome because parenting an infant (especially after giving birth) stimulates the greatest brain plasticity adults ever experience. This neurological remodeling facilitates new behaviors and responses that promote successful, rewarding caregiving. If adoptive parents, fathers, and mothers of C-section and preterm infants provide enough undivided attention and KC to develop and maintain bio-behavioral synchrony, they can still create secure, loving bonds with their child.
Social Conditions Also Play a Role
Unfortunately, many families face additional disadvantages. According to research conducted by Feldman and others, economic precarity, food insecurity, chronic mental or physical pain, living in dangerous communities or relationships, and social isolation can (and often does) prevent parents from engaging in bio-behavioral synchrony.
Maternal anxiety and depression can inhibit the development of infant/parent synchrony, according to Feldman's research. That is because synchrony requires being fully, viscerally engaged in the moment. When we are distracted, stressed, anxious, depressed, or otherwise emotionally unavailable, synchrony doesn’t happen.
Could the confluence of rising rates of C-section and preterm births, postpartum depression, economic precarity, and social inequality partially account for the astonishing fact that 40 percent of Americans are now struggling with mental health and substance abuse, with rising rates of adolescent suicide and mental illness?
Implications for Doctors, Parents, and Society
While Cesarean births are sometimes medically necessary and life-saving, too often the deciding factors are far less compelling. Research indicates that due to confirmation bias, doctors whose last patient had complications frequently chose the opposite delivery method for their next patient, perhaps an indication they allowed their lingering feelings about the previous outcome to sway their analysis of the case at hand. If their last delivery went smoothly, they were similarly biased toward repeating that birth method.
Doctors and expectant parents must be educated about the true costs of C-section births, and how to mitigate them. Ideally, American parents should also be supported by paid parental and medical leave, affordable medical care, and parent education, as well as freedom from food insecurity.
Every child deserves a birth and infancy that supports, rather than impedes, their development into a psychologically healthy, prosocial adult. This means reducing C-section births, but it also means giving all parents the skills, knowledge, and basic security required for developing social synchrony.
