[back] Full term breastfeeding

Sustained Breastfeeding

by Kate Mortensen Grad Dip (Counselling), IBCLC, NMAA Counsellor


Reproduced from 'HOT TOPIC'
Number 7 July 2001
Exclusively for Lactation Resource Centre subscribers


The aim of this paper is to briefly look at the current recommendations and research on breastfeeding duration of one to two years or beyond. All over the world children were commonly breastfed for two to three years until the widespread introduction of Western artificial feeding products (Dettwyler 1995). In the 21st century in Australia mothers find themselves in the position of having to justify breastfeeding the older child to friends, family, social workers, legal and health professionals. While the superiority of breastfeeding is acknowledged, the duration of breastfeeding can still be a contentious issue. Many of the studies on breastfeeding using relatively short periods of breastfeeding have found strong evidence that, even in a well-resourced population, breastfeeding confers many advantages (Brodribb 1997). These advantages would not be expected to cease at 12 months (Lawrence & Lawrence 1999). The definition of sustained breastfeeding in the literature varies widely. Some authors consider breastfeeding beyond three months as prolonged, others six or nine months. This paper examines research that looks at the breastfed child from around 12 months and beyond, where it is possible to find such research.

Breastfeeding rates in some developed nations

Despite increases in initiation rates beginning in the 1970s, the 1995 National Health Survey showed that only 46.2% of Australian babies were receiving any breastmilk at six months of age. At 12 months of age 21.2% of babies are still being breastfed, this falls to 14.6% after one (1) year (Donath & Amir 2000). This figure falls far short of the 1994 targets for breastfeeding set by the Australian Government for the year 2000 for 80% full and partial breastfeeding at six months. In other developed nations statistics on breastfeeding duration do not usually measure duration beyond six months. In the UK around 21% of infants in the 6-12 month age group were being breastfed, while in Norway the figure is 75% (Hunter 1996). In Italy at approximately 12 months 9.3% were being breastfed (Faldella et al 1998), in Sweden approximately 45% at nine months (Zetterstrom 1999). In the US 21.6% were breastfeeding at six months (Ryan 1997). From these statistics it is difficult to say exactly how many babies are being breastfed beyond 12 months. However in the US and Australia, where the highest rates of breastfeeding correlate to higher income and older age of mother, this group has been identified as the group more likely to practice sustained breastfeeding. In Australia 21.2% still breastfeeding at 12 months represents a substantial number of mothers and babies (Prentice 1991, Donath & Amir). Sustained breastfeeding that is continued into the second or third year may be more prevalent than is commonly thought, because many mothers do not talk about breastfeeding the older child for fear of negative comments. The term "closet nursing" is used to describe these mothers by La Leche League members and here in Australia it is common for mothers to receive critical comments if they are breastfeeding an older child. (NMAA Newsletter 1999, 2000; Wrigley 1990).

What does the research say about sustained breastfeeding?

Immunological effects

Sustained breastfeeding provides valuable nutritional and immunological benefits (Lawrence & Lawrence 1999). Goldman and Goldblum (1983) showed that immunologic components of breastmilk are maintained into the second year of lactation and are still providing protection to the infant. The data showed that the production of IgA antibodies operates throughout lactation. Gulick found breastfeeding was inversely associated with episodes of illness in infants. He found breastfed infants had less episodes of illness as toddlers between the ages of 16 and 30 months. Human milk continues to provide valuable nutrition and immuno-protection beyond the baby's first year. Objections to continued nursing are principally based on custom in addition to a lack of knowledge about the ongoing value of breastmilk. Lawrence states that while research documents protection and improved development for at least two years there is also a positive emotional and bonding experience with long-term nursing. "Thousands of normal healthy children are breastfed until they are three or four years old" (p 346).

Cognitive development

Enhanced cognitive development has been shown to be positively associated with duration of breastfeeding. Rogan and Gladen (1993) tested children, some of whom were breastfed up to two years, for IQ and school grades. The results showed a dose dependent relationship between higher score and duration of breastfeeding. Horwood et al (2001) studied 214 very low-birthweight children who were assessed for cognitive ability at seven to eight years. Mothers' retrospective recall of breastmilk feeding was cross checked with hospital records and child health record books were also used to aid maternal recall. Using the revised Wechsler Intelligence Scale the authors found a six point advantage in verbal IQ for infants who received breastmilk for eight months or more compared with those who did not receive breastmilk. They also found a clear and significant dose response relationship even after controlling for confounding factors. This study points to the growing body of evidence for the beneficial effect of breastmilk on cognitive development.

Obesity and nutrition

Kries (1999) in a cross-sectional study found a clear, inverse, dose-response relationship between the duration of breastfeeding and incidence of obesity and overweight. Longer breastfeeding duration was a significant protective factor, attributed to the composition of breastmilk rather than other lifestyle factors which were adjusted for. In a study of affluent United States infants, those who stopped breastfeeding before 18 months gained more weight from 12 to 24 months, but were the same in length, in comparison with the infants who breastfed for longer than 18 months (Dewey et al 1995). Whether or not this higher weight gain is an advantage is debatable in affluent populations where there is already a high number of overweight children. In a recent report, type-one diabetes was linked with higher weight gains during the first year of life (Bruining 2000). In the isolated situation where inadequate weight gain is a concern, encouraging greater consumption of good quality complementary foods is advisable rather than ceasing breastfeeding (WHO 1998).

Another study of mothers who breastfed for 12 months or more showed a more relaxed attitude to feeding their toddlers and they were less likely to exhibit high levels of control over when and what their toddlers ate and drank. The increased intake by toddlers of a variety of foods as well as the fact that these toddlers were leaner but taller was attributed to the maternal style of feeding which accompanied longer-term breastfeeding (Fisher et al 2000). The Toowoomba Children's Nutrition Study (1999) showed that breastfed infants consumed significantly less full-cream milk, soft drink, cordial and soy drinks at 12 months of age.

The study by Marangoni et al (2000) showed that concentrations of arachidonic and docosahexaenoic as well as polyunsaturated fatty acids remain stable in breastmilk through the period of breastfeeding from one month to 12 months. Research by Kent et al 1999 also showed that while breastmilk volume declined it remained a substantial part of the toddlers diet They also showed that milk production responds to infant demand throughout lactation. 500 ml/day of breastmilk can provide about one-third of the protein and energy, 45% of vitamin A, and almost all of the vitamin C that a child needs in the second year of life (WHO 1993).

Bone density

Backstrom et al (1999) followed a group of pre-term infants and found that while mineral supplementation in the short term showed better bone mineralisation, this advantage was not sustained long term. The greater the amount of breastmilk infants received, the greater bone mineral acquisition in the long term. The periods of lactation studied went up to 12 months. (This was considered a long period of lactation by the authors.) The authors recommend a long period of breastfeeding to optimise long-term bone mineral acquisition.


Sustained breastfeeding has been assumed by many to be as much a risk factor for dental caries as formula-feeding, although the research is incomplete and contradictory. Speller (2000), reviewed the evidence and concluded that, a small number of breastfed babies are more susceptible to dental decay than others. However this is due to a number of other risk factors, including excessive consumption of sugar-rich weaning foods and drinks; family history; fluoride exposure; mothers health and diet during pregnancy; prematurity and dental hygiene. Nevertheless bottle-fed babies are significantly more likely to develop caries. Further research is required into all the risk factors for dental caries.

Mother-child attachment

Breastfeeding promotes mother-child attachment and bonding which in turn may lead to a greater sense of security for the child (Fergusson & Woodward 1999; Ainsworth 1973). The emotional benefits of breastfeeding the older child were emphasised by mothers who cite them as being the most important reasons for continuing to breastfeed. (Kendall-Tackett & Sugarman 1995; Fergusson & Woodward 1999; Hills-Bonczyk 1994). Breastfeeding is both a biological and a cultural activity that is modified by a wide variety of beliefs. Beliefs about the nature of human infancy, the relationship of mother and child, mothers' work expectations, and ideas about personal independence and autonomy will affect the breastfeeding relationship (Dettwyler 1995). Reasons for weaning early can include a mistaken belief that a child will become too dependent and have difficulty separating from the mother. Ainsworth's (1973) research showed that a secure attachment to the mother through breastfeeding enabled children to form attachments to others and to become more independent than a comparable group of bottle-fed infants. In Fergusson and Woodward's (1999) study those children breastfed for a longer duration tended to perceive their mothers as more caring and less over-protective. Mothers in this study who elected to breastfeed were more likely to come from advantaged socio-economic backgrounds; however, even after adjusting for these factors, adolescent perceptions of higher maternal care were significantly associated with duration of breastfeeding.

Effects on the mother

Sustained breastfeeding also provides many benefits to the mother including lower risk of anaemia, longer periods of lactational amenorrhea, reduced risk of osteoporosis and breast cancer, promotion of postpartum weight loss and sense of personal achievement.

Research by Sinigaglia et al (1996) found that women with a median lactation of 22 months were not significantly different in bone mineral density to other matched groups who had either lactated for a shorter time or not at all. Melton et al in 1993 studied a random sample of 304 white women in the United States. showed that breastfeeding beyond eight months was associated with greater bone mineral density in later life. Reduced risk for osteoporosis has also been found in other studies with even shorter durations of breastfeeding.

Studies from China and Japan have previously shown a reduced risk for breast cancer. More recently Zheng et al (2000) showed that prolonged breastfeeding significantly reduced breast cancer risk, especially for those with a total lactation duration greater than 72 months. This duration of lactation has not been studied in Western populations leading the authors to believe that this is the reason why such a strong protective effect has not been apparent in Western studies.

Mothers find-long term breastfeeding rewarding and natural. They enjoy the close bond that develops with their child; the main difficulty was being 'strong' in the face of negative reactions. These were the main themes that emerged from a prospective longitudinal study of 82 primiparas examining attitudes and reasons for long-term breastfeeding (Hills-Bonyczyket et al 1994).

Around the world

In many countries of the world breastfeeding does continue well into childhood, two to three years and longer. For example by about two years of age a third or more of the children in sub-Saharan Africa were still breastfeeding. In five out of seven Asian countries studied, 50% or more were still being breastfed at two years; in Bolivia, Peru and Guatemala 40% of children; and in Indonesia 63% of children are still breastfed at this age (Haggerty & Rutstein 1999). In the developing nations, sustained breastfeeding is vital to a child's health and growth (Prentice 1991). At one time extended lactation was considered a risk factor for malnutrition and growth stunting. However subsequent research has confirmed that these findings were due in part to reverse causality, as mothers continued to breastfeed a child who was sick or malnourished, while healthy strong children tended to be weaned a little earlier (Simonden & Simonden, 1998). In Peru mothers will relactate if a recently weaned child falls sick (Marquis et al 1997). Fawzi et al (1998) found that child undernutrition had no association with prolonged breastfeeding, only with poverty and illiteracy. In rural China exclusive breastfeeding for up to 12 months, combined with extended breastfeeding, resulted in good growth and nutritional status (Taren & Chen 1993; Prentice 1994). In developing countries prior to the Innocenti Declaration and the launch of the Baby Friendly Hospital Initiative, campaigns to encourage breastfeeding for two years were successful in increasing breastfeeding rates. As the focus shifted to the importance of exclusive breastfeeding in the early months, breastfeeding the older child received less attention. In developed countries also, international agencies, doctors and academics have not strongly advocated sustained breastfeeding beyond 12 months, nor do training courses for medical and nursing students pay enough attention to the management of sustained breastfeeding (Haider, WHO Report 2000). Kathryn Dewey (WHO Report, 2000) points out that while improved complementary foods along with promotion of sustained breastfeeding show good growth effects, recommendations need to be cautious about amounts of complementary foods to avoid displacement of breastmilk in the infant's diet. This caution applies to Australia as when solids are introduced to an infants diet they often replace rather than complement breastfeeding. This may be quite deliberate with some mothers as they wish to wean their babies, while other mothers may find their infants weaning prematurely.


Anthropologist Katherine Dettwyler (1995) posed the question of what would be the natural age of weaning, if we were free from cultural beliefs. By looking at age of weaning in other large mammals, particularly primates which are closest to humans, Dettwyler estimated the natural age of weaning to be around two and a half to seven years of age. The markers for weaning in large mammals and primates include quadrupling of birthweight; attainment of one-third adult weight; adult body size; gestation length; and dental eruption. In humans, quadrupling of birthweight occurs at around 27 months for males and around 30 months for females. Dettwyler also concludes that while improved sanitation, vaccines and antibiotics can compensate for not breastfeeding to some degree, the physical, cognitive and emotional needs of the young child still exist.


  • Anthropological evidence shows that humans have evolved to breastfeed for several years.
  • Duration of breastfeeding is affected by all aspects of our culture. Biologically and historically and in most cultures, sustained breastfeeding is normal.
  • Those mothers from areas where sustained breastfeeding is uncommon need to access extra support from health professionals and support groups such as NMAA (Australian Breastfeeding Association from August 1, 2001) and La Leche League International.
  • Further research in the area of psychological, cognitive and physical benefits to mother and child of sustained breastfeeding would fill a gap in the knowledge of early childhood development.


The following policy statements inform health professionals, support mothers and help to promote a change in attitudes towards sustained breastfeeding.

  1. The National Health and Medical Research Council in Australia (1995) Dietary Guidelines for Children and Adolescents. (1996) Infant Feeding Guidelines for Health Workers recommended exclusive breastfeeding for the first four to six months (new draft guidelines [submitted for public comment July 2001] state 'about six months') with breastmilk still the most important part of the baby's diet for up to 12 months. Breastfeeding is then to continue into the second year. There is no set upper age limit to breastfeeding.
  2. Royal Australian College of General Practitioners. The position paper by the Royal Australian College of General Practitioners recommended exclusive breastfeeding for six months then gradual introduction of complementary foods. Breastfeeding to continue for as long as the mother and child wish. The RACGP position paper includes the UNICEF recommendation that breastfeeding should be sustained for at least two years after six months of exclusive breastfeeding.
  3. American Academy of Pediatrics 1997, Breastfeeding and the use of human milk. Pediatrics 100(6): 1035-1039). The American Academy of Pediatrics recommended gradual introduction of solid foods in the second half of the first year. Breastfeeding to continue for at least 12 months and then for as long as mutually desired.
  4. The World Health Organisation recommended 6 months of exclusive breastfeeding, then breastfeeding to two years and beyond in addition to appropriate complementary foods (WHA54.2 May 2001).