**4. Breastfeeding in the twenty-first century**

**1. Introduction**

28 Selected Topics in Breastfeeding

The newborn's brain grows at an accelerated rate during the first 1000 days and this is associated with myelination of the white matter. Furthermore the brain growth and myelination correlates with the stages of brain development, including motor, speech, vision, acquisition of social skills, attachment, learning math and logic. All aspects of infant's growth and development are contingent on his genetic code "nature". However gene expression is influenced by epigenetic factors "nurture". The positive environmental factors result in neurobiological changes and improved neuroplasticity. The neurobiological effects of environmental enrichment was first reported by landmark work of Volkmar and Greenough which clearly demonstrated the superior problem solving abilities of rats raised as pets compared with rats raised without such human interactions [1]. Anatomically the environmental enrichment resulted in greater cerebral volumes, larger number of synapses and increased complexity of dendritic branches [1]. Extensive animal research demonstrate that maternal grooming and nurturing can lead to changes in DNA methylation, resulting in gene suppression or histone acetylation, up-regulation of the gene expression, which increase grooming in the offspring when it matures and the cycle repeats itself [2].

Neuropeptide hormones and their receptors have properties that identify them as candidates for the induction of early life experiences into both short and long-term behavioral changes [3]. Animal research has provided a vast knowledge on the significance of the role of mother-baby interaction in child development. The elegant experiments on prairie voles, small monogamous mammals, point to the significant role of oxytocin on our behavior. Injection of oxytocin receptor blockers resulted in changes in pair-bonding behavior in these mammals [3]. Additionally oxytocin is implicated in all aspects of romantic and maternal love, including

Anthropological studies demonstrate significant differences between the breast milk of large primates such as humans, monkeys and apes, referred to as "carrying mammals" vs. "nested mammals". Carrying mammals' breast milk contains lower amount of fat and sugar, while the nested mammals' breast milk contains much higher sugar and fat. Therefore carrying

The human infant's central nervous system depends on a micro-environment that is similar to the maternal uterine environment which is full of sensory exchanges involving heat, sound, movements, transportation, feelings, touch, smell and access to nutrients in the mother's breast milk. For species such as primates, the mother is the environment (Sarah Blaffer Hrdy).

The first 1000 days is the most significant period of an infant's life. During the first 3 years there is great potential for the infant and toddler to acquire immense cognitive, visual, speech,

mammals require to breastfeed their infants more frequently than nested mammals.

**2. The role of oxytocin on brain development**

courtship, mating, pregnancy, childbirth and breastfeeding [3].

**3. The first 1000 days last a life time**

motor and emotional development.

Mother's breast milk is an extension of her placenta which provides nutrients, hormones and epigenetic factors that carry messages to the infant to regulate his metabolic pathways.

World Health Organization (WHO) recommends breastfeeding for 2 years. Extended breastfeeding up to 3 and 4 years of age is highly recommended for additional calories, proteins, lipids, vitamins and factors that regulate the child's metabolic processes. The myelination of the nerve fibers continues, although at a slower pace until early adolescence.

The global breastfeeding rate in the past 10 years has improved only marginally from 33% in 1995 to 37% in 2014 [4]. Suboptimal breastfeeding results in higher health care expenditure for pediatrics and maternal care, and global productivity-related economic losses of \$302 billion or 0.49% of world gross income annually [4].

Maternity and pediatric care providers in many parts of the world do not follow the recommendations of WHO on breastfeeding for 2 years or longer. The policies of several governments do not support breastfeeding including the Chinese government which subsidizes domestically manufactured formulas and US government that provides free formulas to low income families on WIC, Women, Infants and Children's program. WIC program was originally only intended for low income mothers who were breastfeeding their infants, however the program was extended to formula feeding mothers 2 years later [5].

International efforts to promote and protect breastfeeding on a global scale began in 1981 by WHO and World Alliance of Breastfeeding, WABA, in Geneva, Switzerland. The conference resulted in a significant document, International Code of Marketing of Breast Milk Substitutes. This was followed in 1990 by Innocenti Declaration and the Baby Friendly Hospital Initiative which promotes breastfeeding and rooming in for every newborn resulting in an increase in breastfeeding initiations. Many college educated mothers are cognizant of numerous benefits of breastfeeding and choose to breastfeed their infants.

mother-infant dyad result in the rise in oxytocin in infant's brain. All the sensory stimuli are transmitted via nucleus tractus solitarius (NTS) to release oxytocin from the hypothalamic nuclei, SON and PVN [6]. The act of suckling in calves at the udder result in oxytocin release,

The Influence of Breastfeeding and the Infant's Social Environment on Neuroplasticity and Brain…

http://dx.doi.org/10.5772/intechopen.73209

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During the early and mid twentieth century there was a gradual decline in breastfeeding rate in industrialized nations. This decline is attributed to the global conflicts when bread-winners went to war and the women went to work. The infants and young children were left with a relative to care for them and the majority were given breast milk substitute (formula) or cow's milk. In England, majority of infants and young children were placed in large nurseries in the countryside away from London during World War II. The mothers were allowed to visit their children occasionally. Many children were noted to develop behavior problems and maladjustment as they grew older. The emotional and behavioral problems were attributed to maternal deprivation. Several prominent psychologists and psychiatrists promoted the concept of maternal separation as the root cause of delinquent and maladaptive behavior. Sir John Bowlby who was a member of an aristocratic family was the most prominent of these researchers who was personally affected by maternal deprivation. It was customary in the aristocratic families in England to employ a nanny to take care of the infants and young children. They believed that close contact between the mother and their infants and young children would spoil them. Sir John Bowlby writes that he was only allowed to see his mother for an hour after her evening tea. Naturally he developed attachment to his nanny and when she suddenly left the household when he was only 4 years old, he was quite devastated like losing a mother. Bowlby states that his early life experiences provided the idea of what he later called the theory of attachment parenting. When he was 10 years old he was sent to a boarding school, which was common in aristocratic families in England. After completion of high school he studied psychology, medicine and psychiatry. John Bowlby wrote his first paper in 1958, titled, the nature of the child's tie to his mother, which was followed by a number of papers and books on attachment parenting. However his writings do not include the benefits of breastfeeding, primarily because of the lack of knowledge regarding young infants' nutrition at the time. Subsequently there have been a great number of articles and books which have been published on the subject of attachment parenting which still lack the prominent role of breastfeeding and its role in mother-baby bonding. A number of researchers including Marshall Klaus and later John Kennel have published articles and books regarding the benefit of breastfeeding in bonding and attachment between mother and her newborns [9, 10]. They recommended that the newborns should stay with their mothers and breastfeed as soon as possible after they are born. They also stated that early breastfeeding enhance the motherinfant bonding, increase the likelihood of breastfeeding, improves child development and prevent child abuse and neglect. Furthermore Klaus stated that early mother-baby bonding is the result of the rise in oxytocin in both mother and infant's brain [10]. Critics had made comments regarding the feeling of guilt by the parents who were not able to bond with their

however drinking from a bucket is not associated with a rise in oxytocin [6].

newborns in the hospital and to breastfeed their babies [11].

**5. Attachment parenting**

Majority of nations have ratified the International Code of Marketing of Breast Milk Substitutes, however there are serious violations of marketing by formula industry and court challenges to overturn the marketing code. It is not unusual to hear that some unscrupulous providers in 3rd world countries will give samples of formula to the mothers upon delivery to feed their newborn and deprive the newborn from the benefits of colostrum feeding and later breastfeeding.

There are many obstacles to exclusive breastfeeding of a newborn in US hospitals, some of which are due to flawed hospital policies for newborn jaundice and neonatal hypoglycemia. Some physicians wrongly believe that exclusive breastfeeding will place the newborn at risk of developing hypoglycemia as well as severe jaundice which may lead to kernicterus. Other obstacles to exclusive breastfeeding include the use of pacifiers, nipple shields and providing the mothers with a breast pump to give the breast milk via a bottle to feed the newborn infants.

The high rate of cesarean section in some countries is an obstacle to breastfeeding, because of reduced oxytocin and delayed lactation [6]. Additionally epidural block may result in lower oxytocin release due to the inhibitory effect on Ferguson reflex [6]. Pitocin infusion may result in reduced release of oxytocin via a feed-back inhibitory effect [6]. Therefore it is clear that natural child-birth without epidural block and pain medications result in better outcomes immediately after birth with the newborn latching on and suckling at the mother' breast. Infants born vaginally have higher oxytocin level than infants born by cesarean section, 69 pg/ml vs. 33 pg/ml [6].

Newborns placed on the mother's chest latch on to the mother's breast, attracted to the Montgomery glands around the nipples, which secrete a lubricating liquid. Newborns latch on to both nipples, however when one nipple is washed with soap and water the newborn would latch on only to the unwashed nipple. When the mother's amniotic fluid was applied to the washed nipple, the newborn latched to that nipple. It is generally believed that the liquid discharge from the Montgomery glands have the scent of the mother's amniotic fluid [7]. We have also encountered the statement from the breastfeeding mothers that for the first 2–3 weeks their infants refuse to breastfeed immediately after a shower.

There is strong and convincing evidence that attachment and bonding between the mother and infant is associated with the release of oxytocin from hypothalamic nuclei, peri-ventricular and supra-optic and its binding to peri-aqueductal gray (PAG), insula, inferior and posterior temporal nuclei [8].

Oxytocin and many of the maternal hormones are present in the mother's breast milk. However the concentration of breast milk oxytocin is very low and decreases quickly. Oxytocin is probably digested in the infant's stomach and is not absorbed from the intestinal tract into the circulation. However oxytocin activates cholecystokinin which then activates sensory vagal nerves which release oxytocin from the infant's hypothalamic nuclei [6]. Sucking in the newborn is associated with infant's oxytocin release. Furthermore sensory interactions between mother-infant dyad result in the rise in oxytocin in infant's brain. All the sensory stimuli are transmitted via nucleus tractus solitarius (NTS) to release oxytocin from the hypothalamic nuclei, SON and PVN [6]. The act of suckling in calves at the udder result in oxytocin release, however drinking from a bucket is not associated with a rise in oxytocin [6].
