Why Children Continue Excerpt from Breastfeeding Older Children
"Children who do not get what they deserve become the people that no society deserves, and no individual deserves to be." - Alice Miller1
In western culture, women who sustain breastfeeding for several years tend to be regarded as bizarre, to say the least, but the practice is not without historical precedent. Contrary to the elite practice of using wet nurses, and the pronouncements of male physicians throughout history on early cessation of breastfeeding - both of which can be traced back to the very root of western civilization - historically, for women in lower social ranks, breastfeeding was normal, and often maintained for years.
Apart from early medical commentators (usually concerned with elite women and who mention women from other classes only in the context of wet nursing), the feeding of infants, a matter too ordinary to be spoken about, doesn't appear much in the historical record. We therefore have no idea of the numbers of women who ignored the dictates of Galen and Soranus, but we can be sure that many did; even among the wet-nursed elite. Anthropologist Ian Wickes reported that Plotinus, the 2nd century Greek philosopher, 'at the age of eight used to run from his tutor to his nurse and clamour for the breast'.2 When sustained breastfeeding is mentioned, the inference is clear: the practice was widespread. With the exception of wet nurses (who often weaned their own babies to make a living breastfeeding elite infants), women from the poorer classes routinely breastfed children for 1 - 2.5 years at least, and often for much longer. Tacitus, the 1st century Roman historian, reported that German mothers breastfed for several years.3 'Nothing', it was stated in 1737, 'is more common in Lancashire (among the poorer sort)', 'than for them to let their children suck even for years',4 and in the 1820s it was noted that 8 year olds were commonly breastfed in East Lincolnshire.5 Even with the 20th century advent of artificial feeding in the west, the prohibitive cost meant that women in poorer families continued to breastfeed, and instances of long-term breastfeeding, especially in rural communities, are still anecdotally reported. Indeed, some of today's sustained breastfeeders, and in cases also their mothers and fathers, were themselves breastfed for several years.
Around the globe, sustained breastfeeding has and still does characterize many cultures. Researchers Huggins and Ziedrich, for example, report that among the Sioux a three to five year breastfeeding span was traditional, and also refer to a mother who turned up at school to breastfeed an eight year old in the break because he had a cold.6 In his survey, Wickes found breastfeeding spans such as: two to three years in Australian aborigines, three to four years in Greenlanders, five years in Hawaii and seven years among the Inuit.7 An anthropologist friend recently told me that, despite the ubiquity of infant formula, many Inuit children are still breastfed until this age. There are also many other modern-day hunter-gatherer tribes, and other traditional cultures in the developing world, in which children are breastfeed for up to six or so years.
As this book shows, many women in the industrialized world today practise sustained breastfeeding. These mothers are convinced that ongoing feeding provides physical and emotional health benefits for older children. There have been few physical health studies on children in the developing world breastfed beyond 3 years, and even fewer at that age. To my knowledge, there has been only one small (38 children) physical health study to date on sustained breastfeeding in an industrialized setting. No studies on psychosocial adjustment have been conducted on children breastfed beyond one year. There is, therefore no direct evidence to support (or contradict) the view of these mothers. However, there is other relevant evidence.
Psychology and the mother - child bond
Mothers speak about the emotional advantages children gain from sustained breastfeeding. Though not specifically to do with long-term breastfeeding, Attachment Theory,* which was developed in the 1950s/60s by English psychiatrist John Bowlby and American psychologist Mary Ainsworth and widely hailed as the most influential theory of the twentieth century in child, personality and social relationships development, has great relevance.
Following wide-ranging cross-discipline research, Bowlby came to reject key psychoanalytic cornerstones. In opposition to the psychoanalytic view that children's emotional problems were due to fantasies generated from an internal conflict between aggressive and libidinal drives, Bowlby attributed them to actual family experiences and interactions. He also rejected the psychoanalytic view that an infant's love of its mother derives from sensuous oral gratification, in which need-satisfaction is seen as primary and attachment as secondary. Bowlby maintained that humans exist in what he termed an 'Environment of Evolutionary Adaptedness' in which an infant is born with an evolved innate predisposition for emotional involvement with its mother, with a concomitant urge to remain for protection in physical proximity to her. When the mother is properly attuned to the child, and thus able to read the child's cues, and responds appropriately and in a timely manner repeatedly over time, not only is the growth of security in the child nurtured and the child's trust and confidence in the mother's availability and commitment established, but the child also develops what Bowlby called an 'internal working model' of self and other(s), which forms the basis of the child's thoughts, feelings, memories and beliefs and upon which expectations of relationships are founded.
Bowlby recognized breastfeeding's efficacy to facilitate attachment. A breastfeeding mother's body produces the hormones prolactin, which calms and relaxes both mother and child, and oxytocin, which promotes bonding between mother and child. The breastfeeding dyad** is thus a reciprocal, mutually reinforcing, emotional unit. Mother and child are emotionally impelled towards each other and, as each elicits response and counter-response in the other, initial impulses strengthen and bonds deepen. In lay terms, it is the founding and growth of love. For the child, it is the first relationship; with, as we shall see, ramifications for much that follows throughout life.
Mothers' comments provide a glimpse into the attachment process:
The child learns that someone really cares and reacts accordingly when they have a need. In times of emotional upheaval it is the best place to return to for stability and comfort. South Africa. Child 1: bfd 6yrs; Child 2: bfd 4 yrs; Child 3: bfdg 5 yrs.
Though clear boundaries were set ('no' meant no), I deliberately sought not to impose on my daughter, not only by breastfeeding when she needed, but in myriad other ways. Instead of rushing in, I took cues from her. It was like a dance - she led, I followed. With matching steps we danced through time. And I noticed, again and again over the years, that we were always in synchrony, with both of us always ready at the same time for the next phase of development. There was never any tug and pull between us, just an always-easy synchronous flow. England. Child 1: bfd 6.6yrs.
It's a pleasurable time for us to relax together, where we give and receive love; during breastfeeding we are connected through our bodies, emotions and souls. It's a wonderful relationship. Portugal. Child 1: bfdg 2.9yrs.
I love the closeness and emotional high I get when I feed M (especially when she was tiny, it was like being in love all over again, I suppose I was in love all over again!). England. Child 1: bfdg 2yrs.
Breastfeeding really was a way of life, it wasn't just a feeding method. It's how we, my friends and I, loved our infants - it was our own unique and natural gift and we offered it freely and just responded to our babies. We didn't question times or amounts, we really just tuned in to our little one and went with it. USA. Child 1: bfd 2.3yrs; Child 2: bfd 3.2yrs.
But more than physical, the benefits I see are the satisfaction of nursing those beautiful children, of spending time with them, of cuddling them, of knowing you are giving them the absolute best, of growing together, of bonding. Guatemala. Child 1: bfd 3 yrs; Child 2: bfd 3.3yrs.
The force of attachment and the drive to protect and love their children that mothers experience can be incredibly powerful.
Ainsworth provided empirical validation of Bowlby's theory.*** Her findings revealed that a characteristic of a securely attached child is a willingness to leave its mother and a readiness to explore the surrounding environment, thus signalling the child's trust that the mother will be available when needed.
If mothers are right and children do have a bio-emotional need to sustain breastfeeding for several years, it follows that compliance with this innate need is likely to be reflected in the child's attachment style. There will of course be countless examples of securely attached children not breastfed long-term, or even not breastfed at all, whose parents consciously or unconsciously practised what might be termed 'breastfeeding behaviours' - eg prolonged eye-gazing and close physical contact, perhaps including skin to skin - through early childhood, but here I am dealing with the effects of sustained breastfeeding.
As seen in Chapter 2, many psychologists believe long-term breastfeeding impedes development and interpret a child's wish to continue as indicative of underlying anxiety and insecurity. From my personal experience of sustained breastfeeding and the incontestable evidence of secure attachment and healthy adjustment in many long-term breastfed children known to me, as well as from countless mothers' survey comments, this is clearly not the case.
Apart from numerous health and other benefits, one of the most important things for us was the independence BF seemed to give my son. I often watched other toddlers the same age, who were formula fed or only BF for a short time, and noted how confident my son seemed in comparison. He has never been clingy at toddler groups, just full of life and ready to try new things. England. Child 1: bfd 3 yrs: Child 2: bfdg 11mths.
I think that emotionally my eldest is so loving, and so sweet, and very very secure! I get comments all the time about what a loving child he is. USA. Child 1: bfdg 4yrs; Child 2: bfdg 1yr
Emotionally, he's really confident and outgoing. He always had me there so he always knew he could go and I'd be there, really be there closely, when he chose to come back. He's also bright as a button, very healthy and advanced in lots of things. England. Child 1: bfdg 4.3yrs.
He is also one of the most happy, sociable, confident, non-aggressive children I have observed among the toddlers of friends, relatives and playgroups. Certainly some of this may be due to his personality traits, but I am convinced that a bf child is a happy child and I can see the results in my own son. England. Child: bfdg 2.7yrs.
Ainsworth also observed a time-effect: that early maternal sensitivity was associated with more harmonious mother - infant relationships later on in the baby's life; that babies whose mothers had responded in a timely manner early on, later cried less and were more likely to rely on facial expressions, gestures and vocalizations to signal their needs, and that babies held more early on also sought less contact later. Echoing Ainsworth's observations, and forming a parallel with research studies that have found correlations in relation to cognition and obesity with longer durations of breastfeeding8, mothers say that the close bond they have with their children is not only facilitated by breastfeeding but that the bond is reinforced and deepened when breastfeeding is sustained.
I feel that, emotionally, nursing has helped me to bond with my babies so much better. And that bond just keeps getting stronger. USA. Child 1: bfdg 4yrs; Child 2: bfdg 1yr.
I didn't want a child, yet bonded immediately and profoundly. The breastfeeding was a huge part of this. England. Child 1: 4.3yrs.
Emotionally it's just wonderful to be able to breastfeed an older child. The contact we have while he is feeding is so great, and very different from when he was a baby. And getting so close with him is an even stronger emotional experience now than before. Maybe I feel that way only because over time I love him more and more, I don't know. I love giving him breastmilk when I see the way he loves it so much. Norway. Child 1: bfdg 2.2yrs.
I truly enjoyed nursing my children as they grew. I think the relationship between us strengthened and they were precious moments we spent together. It kept me in close contact with them, I was there for them when they needed me and most of all it started a way of mothering that continues on even now they are teenagers. Guatemala. Child 1: bfd 3yrs; Child 2: bfd 3.3yrs.
We also enjoy a very special closeness now that probably results from the long BF relationship. England. Child 1: bfd 3 yrs; Child 2: bfdg 11mths.
I would never have mothered in any other way, and to this day I sometimes get teary and wistful thinking back on the level of closeness I shared with my nurslings. It was as if we were bound by an invisible electrical current. USA. Child 1: bfd 4 yrs; Child 2: bfd 6.5yrs.
Crying in children, often regarded as normal and unavoidable, is tolerated to a great degree in many western societies, and there is great pressure on children to grow up quickly and learn self-reliance. Emphasis is laid on the training of even young babies. A glance at any bookshop will reveal a plethora of titles offering guidance on baby/toddler/child development: how to sleep-train, potty-train, wean, feed, encourage independence, and methods to show 'who's boss'. Distrust of children is palpable, with an ingrained belief that unless children are schooled and trained they will grow into uncontrollable feral monsters. There is a marked fear and horror of children being spoiled and parents are cautioned about being too responsive and indulgent toward their children.
In contrast, Ainsworth believed that 'an infant whose mother's responsiveness helps him to achieve his ends develops confidence in his own ability to control what happens to him', and, in having needs met by a sensitive and responsive mother, the child, according to Bowlby, develops 'an internal working model of self as valued and reliable'. In other words, the child not only understands that care will always be forthcoming but that she/he is worthy of care and therefore loved; which translates into: I am worth it! I am loveable! Not for nothing did Ainsworth say, 'my advice to parents is not to miss an opportunity to show affection to their babies'. It is a crucial foundation stone of good self-esteem.
Studies have shown that breastfeeding mothers tend to be more responsive to their infants than those that bottlefeed.9 Mothers also comment that sustained child-led breastfeeding - ie, helping 'the child achieve his ends' and allowing the child 'to control what happens to him' - fosters autonomy in the child, and is an ever-repeated demonstration of love and affection that both validates the child (I am worth it! I am loveable!) and nurtures the child's self-confidence (I can do it!) with such confirmation, these children venture boldly out.
I do think both my children are extremely independent and self-assured, my daughter especially. We have a bond that is very special. England.Child 1, now 7: bfd 14mths; Child 2: bfdg 3.9yrs.
Emotionally, he's really confident and outgoing. He always had me there so he always knew he could go and I'd be there, really be there closely, when he chose to come back. He's also bright as a button, very healthy and advanced in lots of things. England. Child 1: bfd 4yrs.
The importance of touch
Ainsworth looked at mother - infant interaction and close bodily contact and concluded that a positive index of each also correlated with secure attachment. Research continues to corroborate the importance of touch. One recent study found that premature babies who received tactile stimulation showed greater weight gain, were more alert and required a shorter hospital stay. That researcher, Tiffany Field, has now founded the Touch Research Institute at the University of Miami School of Medicine, the first institution for the study of touch.
Breastfeeding, of course, entails the closest mother - infant bodily contact possible and also involves skin-to-skin contact (face to breast, at the least) and a breastfeeding mother will also often touch, stroke and pat her child as it feeds - positive interactions that are multiplied many times over, when breastfeeding is sustained for several years. Researchers have also noted these interactions.10
The breastfeeding gives us a lot of physical contact. The feeling of a warm, little child close to me, relaxed and happy, getting the best she can dream of, fills my heart with happiness. Norway. Child 1: bfd 4.3yrs; Child 2: bfdg 1yr.
Regulating negative emotions
According to Attachment Theory, a child cannot regulate its own emotions and only learns to do so through the experience of being regulated. A mother's effective and timely response to her child's early signals of distress, both contain and modulate the child's emotions. For example, when a child feels fear - at a barking dog, or thunder, etc - but realizes, from its mother's emotional signals that there is nothing to fear, the child will quieten. When the mother responds to the child's emotions effectively and in a timely manner, the child's reactions become more proportionate and, over time, the child gradually learns to modulate its own emotions and reactions to events and other people in its surroundings. The ability to quickly and effectively regulate a child's emotions is a significant aspect of breastfeeding. Sustained breastfeeding 'on demand' or 'on cue' - i.e. in accordance with a child's expressed wish or perceived need - has to be the epitome of maternal sensitivity and responsiveness. Not surprisingly, mothers that feed in this way say their children cry little. A study in the Netherlands on problematic crying in two-three month old infants found that breastfed children cry less than their non-breastfed peers.11 Mothers that sustained breastfeeding with subsequent children noted the difference in those not breastfed or weaned early. One mother regulated feeds (in accordance with health professionals' instructions), weaned early and endured two incessantly crying babies. She made this observation:
"It is amazing to see how contented a baby is whose needs are met ... cutting out so much distressing and unnecessary crying. The baby gains immediate confidence in the world that surrounds it."
And here's corroboration from Jack Newman:
"I remember nights in the emergency department when Mothers would walk their ill, non-nursing babies or toddlers up and down the halls trying, often unsuccessfully, to console them, while the nursing Mothers were sitting quietly with their comforted (if not necessarily happy) children at the breast."12
It is interesting to note that Ainsworth also observed that securely attached infants cried little, whereas insecurely attached infants cried frequently, even when held by the mother, and concluded that secure attachment correlated with maternal sensitivity and prompt response to an infant's fussing or crying.
The need for emotional regulation can be all too apparent in the toddler and young-childhood years. Witness a young child in the throes of a tantrum, caught up in a whirlwind of agitation and rage that ratchets ever upward until, locked-into a storm of frustration and anger, the child, shocked and frightened by the ferocity of its own emotions, spirals up into a screaming emotional hurricane - and also see the nearby adult ineffectually trying to connect with the child who, for the time being, is beyond reach. Objectively, the trigger for a child's tantrum may not warrant such an extreme reaction but, subjectively, for the child,it does.
Such intensely negative emotional episodes generally do not occur with a long-term breastfed child. At the onset of any child-distress, the mother has a powerful resource: her breasts, filled with prolactin-laden milk. Breastfeeding restores a child's equilibrium instantly. Mothers who continue to breastfeed children through these critical early years are quickly able to neutralize a child's negative emotions, and thus thwart extreme distress. Gabrielle Palmer, author of The Politics of Breastfeeding and former lecturer at London University, whose children had been weaned by the age of two, said 'I was ignorant and being pilloried by health workers. In retrospect, I know that continuing (to breastfeed) would have helped with toddler tantrums.'13 Mothers also speak of the efficacy of breastfeeding to calm and soothe older children ruffled by external events (also see Ch 9).
"For a baby who was so stressed out from the earliest moments of his life (surgical procedure for tongue-tie), he was calmed easily with nursing... and it sure calmed him down when he was injured or really mad." USA. Child 1: bfd 5.3 yrs.
"I can honestly say my child never even came close to having a tantrum." England. Child 1: bfd 6.6yrs."It is also the magic calm down liquid when they are too angry to reason. I remember times when I have given T milk when he is in a huge temper, unable to gain control and he is almost immediately calmed, and when he has come out of school upset and unable to explain why, but after milk is able to find the right words." England.Child 1: bfdg 7yrs; Child 2: bfdg 3yrs.
"Emotional support and a safe haven no matter what happens." Norway. Child 1: bfdg 2.6yrs.
"As she goes through her day she suffers a lot of bumps and bruises - not so much the physical kind anymore as much as the emotional kind. And while a hug and a kiss might go about 30% towards the healing and restoring she needs, nursing gets her 110% there, the 2 - 3 times a day she needs it." USA. Child 1: bfdg 4.5yrs; Child 2: bfdg 3.5yrs; Child 3: bfdg 7.5mths.
A research study that looked at the association of breastfeeding with maternal bonding and the mother - infant relationship concluded that 'although breastfeeding dyads tended to show higher quality relationships at 12 months, bottle feeding dyads did not display poor quality or precarious relationships'.14 Since the stresses of the (non-breastfed) toddler and young childhood years can be a source of repeated distress for both child and mother and can add strain to the dyadic relationship, the question is begged: would a comparative study of breastfed two-four year olds reach the same conclusion?
Oxytocin, the hormone of pleasure and enjoyment
Regulation of negative emotional states in the child is, however, only one half of the equation. According to Bowlby, 'the infant and young child should experience a warm, intimate, and continuous relationship with his mother (or permanent mother substitute), in which both find satisfaction and enjoyment'. This emphasis on positive emotions has subsequently been validated and extended by technologically assisted advances in neuroscience research.
Biologist and neurobehaviourist, Sue Carter (who considers breastfeeding 'really important'15) pioneered groundbreaking research in the 1980s and revealed the operation of the hormone oxytocin (OT) in the brain. In response to pleasurable interactions, OT is produced in the hypothalamus and then released in pulses into the blood stream via the pituitary gland, and also directly to other parts of the brain and spinal cord, where it binds to OT-receptors. Carter's work also demonstrated the action of OT on parental affiliation to offspring. From extensions to that research (much emanating from Carter's laboratory), it is now known that the physiology of the infant's brain is affected for an extended period by mother - child interactions. Apart from facilitating bonding, OT has a dynamic role in the regulation of both the central nervous system and the autonomic system and plays a crucial part in the infant's brain development, and influences not only physiology but also behaviour. Most OT investigations have been on small mammals (voles, rats and mice), but non-invasive techniques on humans (analysis of urine, saliva, human milk and MRI scans) continue to bear out findings on animals. It is therefore significant that the animal research shows that OT levels can be affected by the type and quality of care giving. Research shows higher OT levels in infants that receive lots of maternal attention compared to those that receive less.
In related work, Tobias Esch, University Medicine Berlin, found that stress hormones have the capacity to cause physiological and behavioural changes,16 and other studies have shown stress hormones can affect OT-receptor binding in the central nervous system.17 Margaret Altemus and Carter examined the effects of lactation on stress responses and found that lactating women had consistently lower reactions to stressors - OT is thought to produce positive emotions by reducing fear and stress. However, though circulating OT may be present, just as glue is inactive without something to bind to, OT needs OT-receptors. Significantly, maternal behaviour can also affect the quantity and quality of OT-receptors in infants. According to Paul Zak, of the Center for Neuroeconomics Studies in California, 'we find in animal studies that if the mother neglects the baby, the number of oxytocin-receptors atrophy'.18 Research also shows that variation in OT-receptors results in variation in maternal behaviour.19 The long-term implications for girl-children, mothers of the future, are clear.
In 2003, with specific reference to breastfeeding and the impact of OT on development, Carter, also shedding light on so-called 'comfort sucking', wrote:
"... the endogenous release of OT within the infant itself may be increased by suckling and tactile stimulation. For example, it has been shown in both young dogs and calves that nonnutritive suckling itself releases OT in the infant. The degree to which bioactive compounds in milk, or changes in OT or other peptides, produced by the infant itself that are secondary to suckling and/or maternal contact, affect physiology or behaviour has only recently become the subject of serious investigation. Still there is evidence that such early hormonal manipulations may affect either the mother and/or the infant, having consequences ranging from brain growth to later stress reactivity ..."20
The breastfeeding dyad is awash with OT. Produced in both the child's and the mother's individual brains in response to initial pleasurable physical contact; then, as feeding continues, pulsatingly reinforced in the experience of mutual joy and pleasure - pictured beautifully by one mother: 'the deep nurturing that returns her all the way back to nearly her days in the womb, floating without a care in the world, nurtured perfectly and held closely with mother's love'. Enjoyment that is further maximized by the frequent, OT-triggering, stroking and patting that, as studies show, accompany breastfeeding.21
In addition, human milk contains OT. Although, the possible effect on the infant of OT obtained via milk is yet to be researched, the effects of prolactin, a related hormone that interacts with OT, are known. To quote Carter again:
"... research in rats has shown that the presence or absence in maternal milk of the related hormone, prolactin ... can permanently modify endocrine function in the offspring... These findings document the capacity of hormones in milk to have long-term physiological consequences. OT and prolactin ... may act as releasing factors on each other... Thus, the presence or absence of prolactin might have indirect effects on OT and vice versa.22
The breastfed infant is thus permeated with OT, produced and released into circulation internally
in response to pleasurable experience, and obtained externally in breastmilk. In breastfeeding these
positive hormonal actions and responses are repeated in every feed; in sustained breastfeeding, they
repeatedly occur and reoccur over many years. In the absence of scientific evidence to the contrary,
it is reasonable to conclude that benefits continue, and accrue, throughout duration.
* For explicaton of Bowlby and Ainsworth's Attachment Theory, I relied, in large part, on Inge Bretherton's 'The Origins of Attachment Theory: John Bowlby and Mary Ainsworth', Developmental Psychology, 1992, 28: 759-75.
** Dyad: a pair of two units treated as one - commonly used to refer to the mother and child.
*** Ainsworth developed a means to gauge a child's attachment to its mother, known as the Strange Situation - a staged set of circumstances in which a child's reactions, to its mother's absence and return, to being alone, and to the presence of a female stranger, are observed) Three types of attachment were identified: Secure Attachment, Ambivalent Attachment and Avoidant Attachment later researchers came up with a fourth: Disorganized Attachment. Secure Attachment defines a secure child and the other styles define types of insecurity. The Strange Situation is in wide use as a child assessment tool.
- A Miller, Banished Knowledge
- I G Wickes, A History of Infant Feeding
- M Odent, The Scientification of Love
- H Bracken, Midwife's Companion
- G Palmer, The Politics of Breastfeeding
- K Huggins and L Ziedrich, The Nursing Mother's Guide to Weaning
- I G Wickes, A History of Infant Feeding
- C G Owen et al, 'Effect of infant feeding on the risk of obesity across the life course: a quantitative review of published evidence', Pediatrics, 2005, 115(5): 1367-77; M C Daniels and L S Adair, 'Breastfeeding influences cognitive development in Filipino children', J Nutr, 2005, 135: 2589-95.
- M Lavelli and Marco Poli, 'Early mother-infant interaction during breast and bottle feeding', Infant Behaviour and Development, 1998, 21(4): 667-83
- N M Else-quest et al, 'Breastfeeding, bonding, and the mother-infant relationship', Merrill-Palmer Quarterly, Oct 2003, Vol 49
- M F van der Wal et al, 'Mothers' reports of infant crying and soothing in a multicultural population', Archives of Disease in Childhood, 1998, 79: 312-17
- Email exchange, 2008
- Phone conversation, 1997
- N M Else-Quest et al, 'Breastfeeding, bonding, and the mother-infant relationship', Merrill-Palmer Quarterly, Oct 2003, Vol 49
- Email exchange, 2009
- T Esch et al, Medical Science Monitor, 2002; and Neuroendocrinology Letters, 2003.
- T Esch and G B Stefano 'The Neurobiology of Love', Neuroendocrinology Letters No3, Jun Vol 26, 2005
- Oxytocin increases trust in humans, Michael Kosfeld, Markus Heinrichs, Paul J. Zak, Urs Fischbacher, Ernst Fehr, Nature 435, 673-676 (2 June 2005)
- D D Francis et al, 'Variations in maternal behaviour associated with difference in oxytocin levels in the rat', Journal of Neuroendocrinilogy.
- S Carter, 'Developmental consequences of oxytocin', Physiology & Behaviour, 2003, 79: 383-97
- Bernal and Richards (1970), cited in N M Else-Quest et al, 'Breastfeeding, bonding, and the mother-infant relationship', Merrill-Palmer Quarterly, Oct 2003, Vol 49
Ann Sinnott has written on health and children's issues for national newspapers and magazines. She lives in Cambridge, England with her 17 year-old daughter. Breastfeeding Older Children is her first book.