Timing and Techniques
What does weaning mean? Textbooks on pediatrics and mothers’ manuals imply that it is the process by which one changes from one method of feeding to another. Raphael states that the first introduction of solid foods is the true beginning of weaning. The term weaning is derived from the Anglo-Saxon wenian , which means “to become accustomed to something different.” It does not mean the total cessation of breastfeeding but the addition of other things. If one consults the dictionary, however, one learns that to wean is to transfer the young of any animal from dependence on its mother’s milk to another form of nourishment or to estrange from former habits or associations. A weanling is a child or animal who is newly weaned. If one likens breastfeeding to the continuation of intrauterine life, weaning is a “second birth.”
Weaning from a physiologic point of view is a complex process involving nutritional, microbiologic, immunologic, biochemical, and psychologic adjustments. Boys tend to be weaned earlier than girls, possibly because the energy intakes of boys at all ages are greater and male growth rate is more rapid. Psychosocial pressures also trend toward the earlier weaning of male infants.
When discussing the process of weaning a human infant, one might say it is the transfer of the infant from dependence on mother’s milk to other sources of nourishment. If one were to determine the appropriate time for this to take place, it would be based on nutritional needs and developmental goals. Observations among other mammals suggest that achievement of a degree of maturity that allows a pup to forage for food is a trigger for initiating weaning by the mother.
The search for the appropriate weaning time for human infants has produced a number of extremes, from the regimen of J.R. Sackett in 1953 of introducing solids on the second day of life to withholding all solid foods until the infant had sufficient teeth to chew thoroughly, a method described by Bartholomaus Mettinger, a German physician, in 1473. The birth of the infant food industry began with German chemist Justis von Leitbig in 1867. He marketed “the perfect infant food” to the public at the turn of the twentieth century, a mixture of wheat flour, malt flour, and cow milk. Jacobi, the father of modern pediatrics, advised no solids for a year and no vegetables before 2 years of age. Thus the winds of weaning varied by culture, ethnic group, medical intervention, and financial resources.
Acknowledging that humans are primates, Dettwyler recognized that lactation and weaning occur according to certain regular patterns in nonhuman primates. She searched for a natural age of weaning for human infants uninfluenced by culture and trends. Evaluating various “rules of thumb” for determining weaning age by biologic references, she found them inappropriate. Breastfeeding from an anthropologic point of view is both a biologic process and a culturalized activity. In primitive cultures, the age of weaning from the breast was between 2 and 5 years, averaging 3 to 4 years.
If the definition of weaning is used to mean the cessation of all feedings at the breast, the age at weaning in nonhuman primates and other mammals is a function of genetics and instinct. Primates have a longer gestation, greater infant dependency, longer life spans, and larger brains per unit of body size than other mammals. Dettwyler suggests that a possible formula for weaning is the ratio of present weight to birth weight as 4 to 1; that is, the offspring weans when four times the birth weight is achieved, usually between 2 and 3 years for well-fed healthy human infants.
If weaning according to attainment of one third the adult weight is used as the rule of thumb, Dettwyler notes the variations in size of human adults by ethnic and cultural groups. The average weight of an adult woman is 54 kg (119 lb); one third is 18 kg (39½ lb), a weight achieved between 4 and 7 years for girls. The average weight of an adult man is 59 kg (130 lb); one third is 19.3 kg (42½ lb). This would mean boys would be nursed longer. The present tendency for obesity in the developed world would accentuate these calculations. The average female weight in the United States is 55 kg (121 lb). The following is an equation for calculation of weaning age:
Weaning age days = 2.71 × adult female weight kg
Thus, a modern infant whose mother weighed 55 kg would be weaned at 1228 days, or 3.36 years. Calculating for small, medium, and large women, this period would range from 2.8 to 3.7 years.
When length of gestation is used as the determinant for weaning time, the weaning/gestation ratio can be determined. The ratio across primate species varies from 0.41 in the Galago demidovii, a small-bodied primate, to 6.40 in the Pan troglodytes (chimpanzee). The former primates nurse less than half the length of pregnancy (11 of 45 days); chimpanzees nurse 1460 days (228-day gestation). Gorillas nurse for 1583 days (256-day gestation). Because the human is closest to the chimpanzee and gorilla, six times the gestation period might be a more physiologic norm: 54 months, or 4½ years.
When the eruption of the first permanent molar is used as the indicator for complete weaning, it estimates weaning at 5½ to 6 years in humans. Tooth eruption is genetically controlled and comparatively unaffected by diet or disease. Six years is also identified as the time of achieving adult level of immunocompetence in humans.
The range of calculated ages for weaning derived from these formulations ranges from 2.3 years to 6 or 7 years. Before the widespread availability of foods suitable for infants and of artificial formulas, infants were traditionally breastfed for 3 to 4 years ( Figure 10-1 ).
Other species gradually introduce other foods and teach their offspring how to obtain them on their own. Usually the mothers in most species make the determination for final termination and no longer permit the young to nurse. There seems to be a close correlation between age of weaning and age of reproductive maturity measured either as first ovulation (menarche) or average age of first breeding. Dettwyler notes that these markers are also related to body size, with larger-bodied species breastfeeding longer. Gorillas, she notes, breastfeed 4 to 5 years, chimpanzees breastfeed for 4.5 to 7 years, with average age of breeding being at 10 years of age and 11 to 12 years, respectively. When a similar calculation is made for humans, assuming breeding at 16 years of age, duration of breastfeeding would be 3 years. Studies on the milkborne factors that might cue the initiation of weaning in other species have not shown any cause and effect. The rat undergoes a “weaning crisis” during which the anatomy of the gut changes; some enzymes appear and others disappear. Chapter 3 discusses the enzymatic adaptations of human infants.
Among humans, many cultural influences mandate weaning time and process. Public and social pressures have influenced weaning for some families in industrialized society. Few traditional societies wean before 1 year of age, and some do not begin until 2 years of age ( Figure 10-2 ). In ancient Hebrew tradition (c. 536 bc ), breastfeeding duration according to the Talmud was at least 3 years. Aristotle had suggested that women should breastfeed while no menstruation was occurring, failing to recognize that one influences the other (lactation suppresses menstruation). The Romans recommended breastfeeding at least to the age of 3 years. In the Muslim world, especially Africa and the Sudan, however, weaning of children is by the Islamic teaching of the Koran, which advises breastfeeding until at least 2 years of age, with many breastfeeding to age 4 or 5. Before 1979 the average time of complete cessation worldwide was 4.2 years. Hervada and Newman provide a historic review of weaning that also presents recent concerns about iron deficiency and other problems more common to formula-fed infants.
Breastfeeding benefits for an older infant have also been evaluated. In the developing world, breastfeeding continues for at least 1 to 2 years after introduction of solid foods. Major benefits include not only the nutrients but also protective, digestive, and trophic agents that extend the period of infertility in the mother and reduce the incidence and severity of infectious diseases for the infant. A review of middle-class breastfed infants between the ages of 16 and 30 months in the United States revealed a decrease in the number of infections and improved overall health compared with those children no longer breastfed.
Nutritionally, it is appropriate to begin iron-containing foods at 6 months, the time the stores from birth are diminishing. The requirement at this age exceeds that supplied by human milk. An additional source of protein becomes necessary toward the end of the first year of life because the grams of protein needed per kilogram of body weight can no longer be supplied by milk alone as the infant grows heavier. The content of protein in the milk begins to drop slightly after 9 months of lactation. A human infant also needs bulk, or roughage, in the diet. The exact time this need becomes apparent is not known, but it may well be by the end of the first year ( Table 10-1 ).
|WHO||Exclusive for 6 months||Continue 2 years and beyond|
|AAP||Exclusive for 6 months||Continue 1 year and as long as mother/infant wish|
|AAFP||About 6 months exclusive||Continue 1 year/mutually desired|
|ACOG||About 6 months exclusive||As long as possible|
|Healthy People 2010||75% at birth||25% at 6 months|
|Healthy People 2020||Exclusive for 6 months||Continue for 1 year|
Developmentally, an infant is ready to learn to chew solids instead of suckle liquids at about 6 months. It has been suggested that there is a “critical period of development” during which infants can and must learn to chew. Chewing is an entirely different motion of the tongue and mouth from sucking. The sucking fat pads in the cheeks begin to disappear at the end of the first year. The rooting reflex has been lost. Even though all the teeth are not in, the development of good dentition requires chewing exercise.
Role of Development in Initiation of Weaning
Although the developmental milestones of infant behavior are noted to influence the introduction of weaning foods, the development of the gastrointestinal tract plays an equal role. Even the taste buds, which can be identified at the seventh week of fetal life as collections of elongated cells on the dorsal surface of the tongue, are fully innervated over the next weeks. The fetus is known to suck and swallow in utero; sucking is discussed in Chapters 3 and 8 .
When taste becomes a factor in feeding is not known, although a lack of discrimination has been noted in the first weeks of life: infants have consumed formula with high salt or absence of chloride with morbid results. As more women are pumping and storing their milk, a notable number of women have their infants reject the stored milk, which is noted to smell sour. The cause remains unknown. See discussion of lipase and sour milk. Because of the variation in the composition of mother’s milk over a feeding, over a day, and from time to time according to maternal dietary intake, a breastfed infant has a richer range of experience in tasting than a formula-fed infant. Breastfed infants are, therefore, more accustomed to new taste experiences. Similarly, feeding problems in infants are rare in breastfed infants.
Both sucking and chewing are complex movements, having reflexive as well as learned components. The development of the chew-swallow reflex is necessary for the successful introduction of solids. This skill develops sequentially with neuronal development and then is a learned behavior conditioned by oral stimulation. Before this point, when a spoon is introduced, the infant purses the lips and pushes the tongue against the spoon. By 4 to 6 months, the tongue is depressed in response to the spoon and the food accepted, and by 7 to 9 months, rhythmic biting movements occur regardless of the presence of teeth. Biting and masticatory strength and efficiency progress throughout infancy. If a stimulus is not applied when the neural development is taking place, the chewing reflex will not develop and the infant will always be a poor chewer. There is a relationship between prolonged sucking without solids and poor eating. The clinical model for this is a child sustained on parenteral feedings or gastrostomy beyond a year who has tremendous difficulty accepting solids.
For a human infant, nursing also plays a role as a comfort and emotional support, a mechanism often referred to as “comfort nursing.” Inadequate nipple contact may lead to thumb sucking or the substitute use of a pacifier. Young monkeys and apes in the wild do not suck their thumbs, but they do in captivity when bottle fed. Infants of the !Kung tribes in Africa do not suck their thumbs. They are carried by the mother and breastfed in frequent short bursts.
In summary, an infant is ready to explore new feeding experiences at approximately 6 months. Feeding is an important social as well as nutritional encounter. Eating solids and learning to drink from a cup are important social achievements as well. This readiness does not mean the infant is taken from the breast, but that the diet is expanded and now includes solid foods, other liquids, and breast milk. Although a range of qualitative, quantitative, and temporal practices are known, the optimal approach matches the needs and requirements of a given child with the functions and capacities of the body.
Introduction of Solids
The World Health Organization (WHO), the Canadian Pediatric Society, the Paediatric Society of New Zealand, and similar groups in England and Scotland emphasize that weaning is not the termination of breastfeeding but the addition of solids while continuing breastfeeding. The key recommendation on length of exclusive breastfeeding reads as follows:
…to strengthen activities and develop new approaches to protect, promote and support exclusive breastfeeding for six months as a global public health recommendation, taking into account the findings of the WHO expert consultation on optimal duration of exclusive breastfeeding, and to provide safe and appropriate complementary foods, with continued breastfeeding for up to two years of age or beyond, emphasizing channels of social dissemination of these concepts in order to lead communities to adhere to these practices.
The intake of supplementary foods may add nutrients in a less bioavailable form, and it decreases the bioavailability of nutrients in human milk and the intake of other important factors in human milk. Investigators have shown that when solid foods are introduced in the diet of breastfed infants, energy intake per kilogram of body weight does not increase. Solid foods displaced energy intake from human milk in 6-month-old infants even though they were breastfed on demand.
In information collected by Dewey et al. in 1994 on well-nourished breastfed infants, no “faltering” in growth pattern could be identified. In a review of protein and energy during weaning, Axelsson and Räihä conclude that 1.65 g/kg/day from 5 to 9 months and 1.48 g/kg/day from 9 to 12 months are appropriate. The growth of exclusively breastfed infants from 4 to 6 months of age matched or exceeded that of randomly selected breastfed infants given 20% added protein. The exclusively breastfed group received 0.98 g/kg/day, whereas the supplemented group received 1.18 g/kg/day. Thus, protein intake is not a limiting factor with respect to growth that would mandate weaning from the breast. On review of protein requirements for infants and children established by WHO, they were higher than necessary for breastfed infants. Formula-fed infants require more protein because of comparatively poor utilization.
Recommendations for the optimal time to introduce complementary foods to the breastfed infant remain controversial. The Section on Breastfeeding of the American Academy of Pediatrics (AAP) supports the introduction of solids at 6 months in concert with the WHO and UNICEF. This choice was in response to a systematic review of published reports in developed and underdeveloped countries conducted by Kramer and Kakuma that included controlled clinical trials and observational studies in many languages. From 2668 reports, only 36 citations met criteria of an internal comparison group. Rigorous assessment of health outcomes included growth, iron and zinc status, infectious morbidity, atopic disease, neuromotor development, rate of maternal weight loss, and duration of lactational amenorrhea.
This discussion of the weanling’s dilemma (i.e., the choice between the known protective effects of exclusive breastfeeding against infectious morbidity and the theoretical insufficiency of breast milk alone as nutrition) was confirmed again by a Cochrane Review in 2009; 6 months of exclusive breastfeeding is optimal.
In summary, exclusive breastfeeding for 6 months supported appropriate gain in weight and length and adequate iron and zinc status when mother is well nourished, reduced infection rates, provided some reduction in atopy, and had a significant advantage in achieving some developmental milestones. The important conclusion reached by WHO-UNICEF is the recommendation of exclusive breastfeeding for 6 months. In a report published in Pediatrics in 2010, the Section on Breastfeeding of the AAP recommends 6 months.
The challenge of meeting nutrient needs of infants and young children when complementary foods are added is great. It is a period of high nutrient density requirement, especially iron and zinc. In countries where cereal-based porridges with low nutrient density are the weaning foods, deficiencies are common. Iron and zinc need to be accounted for ( Figure 10-1 ).
The duration for which the iron endowment at birth remains adequate varies, so some infants will benefit from additional iron at 4 to 6 months. The data on zinc are meager. The concentrations of zinc in milk decline after the first few months of lactation and are independent of maternal zinc intake. Hepatic stores will sustain levels in the infant, but exogenous zinc will be required and is most readily obtained from meat.
In an effort to teach adolescent mothers to delay introduction of solid foods and weaning from breastfeeding, investigators used home visitations every other week for a year using food frequency questionnaires at 3 months for a subset of mothers. Mothers who only used breast milk (or formula) but no solids were considered optimal feeders. The mothers were exposed to counseling and instructional videos to help them read their infants’ cues, utilize nonfood strategies for managing behavior, and to develop techniques for negotiating with an interfering grandmother. The authors thought these efforts helped these mothers follow the national guidelines and instructions for infant feeding by Women, Infants, and Children (WIC).
Breastfed infants self-regulate their total energy intake when other foods are introduced. No advantage to introducing complementary foods before 6 months has been seen. A review by Foote and Marriott expresses the concern that some infants might need additional nutrients. They point out that the energy density of the food should exceed that of breast milk (4.2 kJ/g or 0.55 to 0.80 kcal/g). They also warn that foods with high phytate levels can interfere with mineral absorption and recommend the avoidance of juices and other drinks. Giving infants solids by 4 months is associated with less positive health outcomes such as increased body fat, higher body mass index, and a greater incidence of wheezing and respiratory illness in childhood, according to Fewtrell et al.
When iron was added to the diet at 4 months by giving iron-rich solids to infants who did not have iron deficiency anemia, the length growth was less than in unsupplemented control infants. Head growth was also slower in iron-supplemented infants. No improvement in weight gain was observed, and the treated infants had more occurrences of diarrhea if their hemoglobin levels were normal. More boys than girls had iron deficiency anemia at 9 months according to Dewey et al.
In the study of nutrient intakes and food choices of 3000 infants and toddlers participating in the Feeding Infants and Toddlers Study (FITS), there were 450 participants in the WIC nutrition program. It was observed that infants in the WIC program were less likely to have ever been breastfed and were more likely to be taking formula. The mean usual intake of nutrients exceeded adequate intakes. Mean energy intake was excessive with little consumption of fruits and vegetables. In the entire study of 3000 infants, 76% were fully or partially breastfed at birth, dropping to 30% at 6 months and to 16% at 1 year. Average duration of breastfeeding was 5.5 months. From 4 to 6 months, more than 65% had been given solids, not all of which were nutrient dense. Sweetened juices, French fries, hot dogs, potato chips, popcorn, pizza, and candy were reported in up to 9% of infants aged 7 to 8 months old.
An infant’s first flavor experiences probably occur in utero. When garlic was ingested by mothers before amniocentesis or delivery, the amniotic fluid smelled of garlic. The normal fetus ingests amniotic fluid in utero and thus experiences those flavors. When breastfed, the infant continues to experience those flavors as a bridging experience to solid foods. Not surprisingly, breastfed infants consume cereal prepared with their mother’s milk more eagerly and in greater volume than when it is prepared with water. In a carefully controlled experiment, infants were fed the cereals by their mothers, who wore facial masks but no perfume to avoid affecting the infant’s interest in the food. The infant’s interest was reflected in opening of the mouth sooner, fewer negative facial expressions, and greater intake. Mennella and Beauchamp suggest that from the perspective of flavors, weaning means “to accustom,” which actually describes what occurs with breastfeeding: the flavors in the milk accustom the infant to new flavors in the transition to solid foods. Putting mother’s milk in the bland cereal is part of the bridging. Infants whose mothers have a more varied diet during pregnancy and lactation tend to adapt to solid foods more readily, according to these investigations.
Weaning to a cup is a natural transfer because infants learn to drink from a cup by 7 to 9 months. The use of fruit juice in the cup was originally encouraged for its vitamin C content. Fruit juice may be replacing milk, however, in the diets of young children. This is a concern because milk is an important source of protein and calcium, whereas nutrients in fruit juices are limited predominantly to carbohydrates, calories, and varying amounts of vitamin C. Juices are also replacing fruit in the diet. Excessive fruit juice consumption reportedly leads to short stature and failure to thrive in some infants, chronic diarrhea in some, and obesity in others. The trend often begins when fruit juice is put in a nursing bottle. The pediatrician should be alert to the exact content of the weaning foods, ensuring adequate protein, calcium, vitamins, and fiber, and to the development of feeding skills, including feeding from a cup and from a spoon.
In practice, human mothers are often the determinants of weaning time, as is true for other species. Some mothers want to nurse for a few weeks and wean to a bottle to go to work. Other mothers wean at 3 months to be free again. , Certainly any time spent breastfeeding is to an infant’s advantage. The critical point in weaning is to make it a gradual adjustment for both mother and infant. The year 2010 health goals for the United States recommend that mothers nurse exclusively for at least 6 months, continuing while adding weaning foods until 1 year and then for as long thereafter as mother and child wish.
A study of the psychosocial factors influencing weaning time in primigravidas was conducted when the 81 participants were 8 months postpartum. Maternal worries about the demands of breastfeeding had a negative effect on the duration. If mothers worried about the demands of breastfeeding, they were more likely to perceive problems with scheduling breastfeeding when they returned to work. Mothers who worried about lack of family support to breastfeed were more apt to worry about the demands of breastfeeding. Those women who saw the practical advantages of breastfeeding did not perceive returning to work as presenting a problem and nursed longer. Medical illness, sore nipples, fatigue, or breast infections were not influential in weaning. Work and scheduling have a larger role in most mothers’ decision to wean.
Gradually replacing one feeding at a time with solids or a bottle or cup, depending on an infant’s age and stage of development, is usually preferable. After the adjustment has been made to one substitute feeding, a second feeding is replaced with a substitute, usually at the opposite time of day. This process is continued until only the morning and night feedings remain. Then these two are gradually stopped. The morning and night feedings can be maintained for some months, and often an infant is nursed well beyond the second year, especially at these times. Mothers who wish to wean partially as early as 3 months may continue the morning and night nursing. This schedule is especially suited to the working mother. The decline in lactation and the regression of the mammary gland occur slowly with gradual weaning.
When an infant is fully breastfeeding and solids are initiated, a feeding of solids is given during the day and breastfeeding continues on demand. As solids are increased and a three-meals-per-day schedule is reached, breastfeeding still continues on demand, although nursings may be fewer or briefer. No nursings need be intentionally omitted in this scheme, although it is important to give the scheduled solids before breastfeeding the infant.
The study of the composition of milk during abrupt weaning revealed that the secretory capability of the mammary gland of women changed dramatically after complete cessation of breastfeeding but that the involuting gland remained partially functional for 45 days. After termination that occurred in 1 day, sample collections were attempted for each breast by manual expression at the same time on days 1, 2, 4, 8, 16, 21, 31, 42, and 45. The concentrations of lactose and potassium decreased, while sodium, chloride, fat, and total protein increased progressively over 42 days. The milk becomes notably salty, but the infants continue to drink the salty fluid. The increase in protein was related to increases in the concentrations of lactoferrin, IgA, IgG, IgM, albumin, lactalbumin, and casein. Concentrations from each breast were similar throughout.
The involution in other species is rapid. For example, complete reabsorption occurs in 7 days in cows. The threshold dose of oxytocin required to elicit milk ejection increased progressively for at least 30 days after termination of breastfeeding. It is thought that a psychological nursing stimulus contributes to this effect in humans because they continue contact with their infants, whereas other species are separated. Experimental animals given oxytocin after weaning also show a delay in involution.
Weaning ages and techniques in a sample of American women who practiced extended breastfeeding were reported by Sugarman and Kendall-Tackett. Women were recruited from La Leche League meetings in the area and nationally, utilizing survey forms (closed-end, self-administered, 96-item questionnaires). Based on 134 mothers and 211 children, the weaning age ranged from 1 month to 7 years 4 months. For those who weaned three children, as well as the entire sample, the tendency was to nurse the youngest the longest, perhaps because it was not supplanted by a sibling.
Reasons for weaning were predominantly child-led for about 60% of children, but weaning was the mother’s decision in up to 15.8% in the youngest child ( Tables 10-2 and 10-3 ). Those who were still nursing responded to the question, “Have you thought about weaning this child?” predominantly with a “no” ( Table 10-4 ).
|Child A * ( n = 25)||Child B * ( n = 125)||Child C * ( n = 69)|
|Reasons for weaning (%)|
|Lack of information||5.3||4.2||8.7|
|Lack of support or opposition||2.6||4.2||8.7|
|Next pregnancy affected taste or supply of milk||7.9||14.3||8.7|
|Next pregnancy affected mother’s motivation||5.3||21.8||24.6|
|Illness or separation from child||5.3||5.9||11.6|
|Child-led, happened naturally||63.2||57.1||52.2|
|Mother’s decision that child was ready||15.0||13.4||10.1|
|Mother’s decision based on family circumstance||7.9||5.0||4.3|
|How weaning was accomplished (mean %)|
|Mother deliberately weaned||2.6||11.0||13.2|
|Mother encouraged weaning by talking to child||23.1||31.4||20.6|
|Substituted thumb, pacifier||2.6||3.4||1.5|
|Number of reasons (mean)||1.8||1.8||1.7|
|Reasons Cited as Important||Infants’ Age When Breastfeeding Was Completely Stopped (mo)||Average|
|< 1||1-2||3-5||6-8||≥ 9|
|My baby had trouble sucking or latching on *||51.7||27.1||11.0||2.6||1.5||19.2|
|My nipples were sore, cracked, or bleeding *||36.8||23.2||7.2||5.7||4.2||15.4|
|My breasts were overfull or engorged *||23.9||12.3||4.8||1.6||1.2||8.8|
|My breasts were infected or abscessed *||8.1||5.7||3.1||3.1||3.1||4.6|
|My breasts leaked too much *||14.1||8.0||3.8||1.6||1.9||5.9|
|Breastfeeding was too painful *||29.3||15.8||3.4||3.7||4.2||11.3|
|Breastfeeding was too tiring *||19.8||17.2||11.0||7.8||5.3||12.2|
|Breastfeeding was too inconvenient *||20.4||22.4||18.6||12.5||4.2||15.6|
|I wanted to be able to leave my baby for several hours at a time *||11.2||24.1||18.2||15.6||7.3||15.3|
|I had too many household duties *||12.6||14.0||9.6||5.2||18||9.0|
|I wanted or needed someone else to feed my baby *||16.4||23.2||21.0||17.2||6.1||16.8|
|Someone else wanted to feed the baby *||13.5||15.5||120||5.7||3.4||10.0|
|I did not want to breastfeed in public *||14.9||18.6||15.1||4.7||4.6||11.6|
|Breast milk alone did not satisfy my baby *||49.0||55.6||49.1||49.5||43.5||49.5|
|I thought that my baby was not gaining enough weight *||23.0||18.3||11.0||14.1||8.4||15.0|
|A health professional said my baby was not gaining enough weight *||19.8||15.2||8.6||9.9||5.0||11.7|
|I had trouble getting the milk flow to start *||41.4||23.2||19.6||14.6||5.7||20.9|
|I didn’t have enough milk *||51.7||52.2||54.0||41.8||26.0||45.5|
|I did not like breastfeeding *||16.4||10.9||6.2||1.1||1.9||7.7|
|I wanted to go on a weight-loss diet *||6.6||7.2||10.3||10.9||6.5||8.3|
|I wanted to go back to my usual diet *||5.5||9.5||7.2||5.2||5.0||6.5|
|I wanted to smoke again or more than I did while breastfeeding||6.0||5.2||3.4||1.0||0.8||3.3|
|I wanted my body back to myself *||8.9||13.2||16.8||18.8||15.7||14.7|
|My baby became sick and could not breastfeed *||9.5||7.4||5.5||6.3||19||6.1|
|I was sick or had to take medicine||14.4||16.3||14.8||12.5||8.0||11.2|
|I was not present to feed my baby for reasons other than work||3.2||6.9||5.2||5.2||2.7||4.6|
|I became pregnant or wanted to become pregnant again *||1.7||3.4||3.4||6.8||12.2||5.5|
|I could not, or did not want to, pump or breastfeed at work *||11.2||22.4||21.3||13.5||4.6||14.6|
|Pumping milk no longer seemed worth the effort that it required *||16.7||21.2||23.1||17.7||11.5||18.2|
|Infant’s self-weaning factor|
|My baby began to bite *||5.2||5.7||13.4||38.5||31.7||18.9|
|My baby lost interest in nursing or began to wean himself or herself *||13.2||19.7||33.1||47.9||47.3||32.2|
|My baby was old enough that the difference between breast milk and formula no longer mattered *||5.2||11.4||16.5||26.6||28.2||17.6|