Maternal Instinct is Rooted in Biology and Expressed Through Culture
Throughout history, maternal instinct has consistently highlighted the need for mothers to maintain physical closeness with their newborns. Cultural traditions globally, from China’s “zuo yuezi” to Latin America’s “la cuarentena” and India’s “sitting the month,” reinforce this instinct. These practices demonstrate an intuitive understanding that mother-infant closeness immediately after birth is vital for maternal recovery, emotional bonding, and infant health.
Another historical practice deeply rooted in Europe is the “tenth month” or “lying-in” period. Traditionally lasting about 40 days, this postpartum custom required mothers to rest extensively, staying predominantly in bed while close female relatives or midwives managed household chores and provided physical and emotional support. Mothers remained physically close to their newborns, focusing on bonding, recovery, and establishing breastfeeding. Nutritionally dense and warming diets were emphasized to strengthen maternal health, prevent complications, and support optimal milk production. This dedicated postpartum care significantly promoted maternal healing, strong infant attachment, and stable emotional and psychological well-being for both mother and child.
Historically, many cultures have further strengthened mother-infant bonds through baby-wearing practices. African cloth wraps, Asian sling carriers, and Indigenous American cradleboards are traditional methods that have facilitated consistent physical closeness, regulating infant breathing and temperature, enhancing emotional attachment, and fostering secure infant attachment patterns.
Co-sleeping, another ancient postpartum tradition, is practiced globally and provides benefits for both mother and baby. This practice supports breastfeeding by making nighttime feeding more accessible, helping mothers produce more milk and enabling quicker postpartum recovery by facilitating uterine contractions. Examples include traditional Japanese “kawa no ji” sleeping arrangements and Scandinavian family bed-sharing practices. Co-sleeping promotes emotional security, enhances maternal-infant bonding, and reduces infant stress.
Hormonal Drivers of Mother-Infant Bonding
The biological need for mother-infant closeness is driven by hormones such as oxytocin, serotonin, norepinephrine, epinephrine, dopamine, and cortisol:
- Oxytocin promotes emotional bonding, reduces stress, and encourages nurturing behaviors.
- Serotonin stabilizes mood, reducing anxiety for both mother and child.
- Norepinephrine and Epinephrine help manage stress responses and promote alertness in newborns.
- Dopamine reinforces positive feelings and supports mother-infant bonding.
- Cortisol levels decrease through skin-to-skin contact, reducing stress and enhancing physiological stability.
Together, these hormonal interactions underscore the biological necessity of maternal closeness.
Quantifiable Health Benefits of Skin-to-Skin Contact
Cardiovascular Stability in Infants Improves
Direct skin-to-skin contact stabilizes infant heart rates and significantly lowers stress hormones like cortisol. Electrocardiogram (ECG) monitoring shows fewer episodes of abnormal heart rhythms in infants receiving maternal closeness.
Skin-to-Skin Accelerates Brain Development
Neuroimaging studies using EEG and MRI clearly show stronger neural connections and increased brain growth in infants regularly held skin-to-skin. This directly translates into better memory, attention, and motor skills.
Maternal Contact Extends Infant Sleep Quality
Clinical studies measuring sleep stages confirm that infants who regularly experience physical closeness have longer periods of deep, restorative sleep, essential for emotional health and brain development.
Skin-to-Skin Lowers Maternal Stress and Depression
Research clearly shows that regular maternal-infant contact significantly reduces maternal stress, measurably decreases postpartum depression (as measured by standardized assessments like the Edinburgh Postnatal Depression Scale), enhances breastfeeding success, and strengthens emotional bonds.
Misleading Conclusions from Poorly Designed Skin-to-Skin Research
Decades of scientific research and thousands of years of maternal wisdom have consistently demonstrated that skin-to-skin contact provides significant benefits for mothers and their babies, including enhanced brain development, emotional bonding, and overall health. Recently, however, a 2025 study published in JAMA Network Open challenged this understanding, claiming skin-to-skin contact offered no clear developmental benefits by age three.
At first glance, this finding might appear surprising, even troubling, for mothers seeking the best practices for their newborns. But upon careful review, the study’s methods reveal serious flaws that undermine its conclusions:
A recent study claimed skin-to-skin contact provided no measurable neurodevelopmental benefits by age three, contradicting extensive existing research and established biological understanding.
A recent study published in JAMA Network Open in 2025 demonstrates how poorly designed research can produce misleading conclusions:
- Excluding High-Risk Infants: This study excluded infants who required intensive care interventions, who are precisely those who could benefit most from skin-to-skin contact.
- Limited Duration of Contact: The study allowed only brief skin-to-skin sessions of two hours, which doesn’t align with established kangaroo care practices recommending prolonged and repeated contact.
- Inadequate Sample Size: Enrolling only 108 infants instead of the planned 136 weakened the statistical validity of the conclusions.
- Subjective Data Collection: Relying mainly on parental questionnaires introduced potential bias, reducing the reliability of the findings.
- Insufficient Follow-up: Concluding follow-up evaluations at two to three years overlooked important long-term developmental benefits associated with prolonged maternal-infant closeness.
Trusting Maternal Instinct and Biological Evidence
Mothers have always instinctively understood that physical closeness with their infants is essential. Skin-to-skin contact naturally activates critical hormonal pathways that reinforce emotional bonds, support breastfeeding, and reduce stress, ensuring optimal health and well-being for infants. Scientific findings consistently affirm these biological truths, validating what maternal instinct has recognized for generations: the irreplaceable importance of physical closeness between mother and child.
Reference: Kristoffersen L, Støen R, Bergseng H, et al. Immediate Skin-to-Skin Contact in Very Preterm Neonates and Early Childhood Neurodevelopment: A Randomized Clinical Trial. JAMA Netw Open. 2025;8(4):e255467. doi:10.1001/jamanetworkopen.2025.5467
