Bonding Matters: The Chemistry of Attachment

by Linda Folden Palmer

Bonding MattersHuman babies are born helpless, needing to be entirely cared for and protected. Luckily, they are born with all the necessary tools and "instructions" to attain such care for themselves, and to become a loved and loving part of their family and society.

The ingrained neural and hormonal interactions provided for parent and child to assist them in this process are among the most powerful in nature. The hormonal cues are clear and compelling and our instincts can provide us with all the appropriate responses. Without taking great efforts to avoid and ignore such urges, parents will naturally follow the advice of their neurons and hormones, nurturing their babies and maintaining physical closeness with them.

Once born, baby's hormonal control systems and brain synapses begin to permanently organize according to the human interactions she experiences. Unneeded brain receptors and neural pathways are disposed of, while those appropriate to the given environment are enhanced.

Hormones in Action

When the infant is born, he is already imprinted on the odor of his amniotic fluid. Formula-fed infants are more attracted to their mother's breast odor than to that of their formula.

Beyond birth, mother continues to produce elevated levels of oxytocin as a consequence of nursing and holding her infant, and the levels are based on the amount of such contact. Under the early influence of oxytocin, nerve junctions in certain areas of mother's brain actually undergo reorganization, thereby making her maternal behaviors "hard-wired."

Prolonged high oxytocin in mother, father, or baby also promotes lower blood pressure and reduced heart rate as well as certain kinds of artery repair, actually reducing lifelong risk of heart disease. Multiple psychology studies have demonstrated that, depending on the practices of the parents, the resulting high or low level of oxytocin will control the permanent organization of the stress-handling portion of the baby's brain.

Women who breastfeed produce significantly less stress hormone than those who bottle-feed. When the father spends significant amounts of time in contact with his infant, oxytocin encourages him to become more involved in the ongoing care in a self-perpetuating cycle. Vasopressin promotes brain reorganization toward paternal behaviors when the male is cohabiting with the pregnant mother.

Elevated prolactin levels in both the nursing mother and the involved father cause some reduction in their testosterone levels, which in turn reduces their libidos. Prolonged elevation of prolactin in the attached parent stimulates the opioid system, heightening the rewards for intimate, loving family relationships, possibly above all else.

Oxytocin -- a Bonding Hormone

Oxytocin is a chemical messenger released in the brain chiefly in response to social contact, but its release is especially pronounced with skin-to-skin contact. In addition to providing health benefits, this hormone-like substance promotes bonding patterns and creates desire for further contact with the individuals inciting its release.

When the process is uninterrupted, oxytocin is one of nature's chief tools for creating a mother. Roused by the high levels of estrogen ("female hormone") during pregnancy, the number of oxytocin receptors in the expecting mother's brain multiplies dramatically near the end of her pregnancy. This makes the new mother highly responsive to the presence of oxytocin. These receptors increase in the part of her brain that promotes maternal behaviors.

Oxytocin's first important surge is during labor. If a cesarean birth is necessary, allowing labor to occur first provides some of this bonding hormone surge (and helps ensure a final burst of antibodies for the baby through the placenta). Passage through the birth canal further heightens oxytocin levels in both mother and baby.