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close this bookFood and Nutrition Bulletin Volume 14, Number 2, 1992 (UNU, 1992, 84 pages)
close this folderPublic health nutrition
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View the documentCaracterización de la lactancia materna en Cuba
View the documentFeeding practices and growth in a healthy population of Cuban infants
View the documentAccuracy of mothers' responses to questions about breast-feeding practices

Feeding practices and growth in a healthy population of Cuban infants

Manuel Amador, Mirta P. Hermelo, Mario Valdes, Marcos Ruiz, and Rafael Bueno

 

Abstract

The feeding practices for a selected sample of 100 infants and the infants' growth were followed from hospital discharge until one year of age. Normal, full-term newborn infants weighing more than 2,500 g whose mothers were 20-30 years old, literate, and married and had received regular prenatal care were selected for the study. The mode of feeding and the infant's weight, length, and body muss index were recorded every 15 days up to 360 days of age. A low prevalence of breast-feeding and early weaning, with early introduction of solid foods, were found. Infants who were bottle-fed from birth were heavier at 90 and 360 days but did not differ in length from those who were breast-fed. This difference was probably due to a higher energy intake in the infants who were never breast-fed.

 

Editor's note

While the survey whose results are reported in this paper was limited to a small. non-random sample in a single locality, it is of wider interest because it confirms a number of earlier and more extensive surveys in Cuba and the findings are similar to trends observed among better-off urban populations in many other developing countries. Under conditions of good primary health care and environmental sanitation, significant differences in growth were not apparent among infants receiving breast-feeding, combined in most cases with mixed feeding. either for 90 days or more or for less than 90 days, and those who were bottle-fed from birth. The results indicate that, under favourable circumstances, early mixed feeding is not necessarily nutritionally disadvantageous.

These results from Cuba obviously do not apply to populations living under conditions of poor environmental sanitation and personal hygiene and poverty. Moreover, they shed no light on the benefits or appropriate duration of nearly exclusive breast-feeding, which is the goal for the early months for all infants. At some point in the first year of life, breast fed infants require appropriate complementary feeding. The Food and Nutrition Bulletin would like to receive reports of well designed studies indicating both the results and the optimal duration of exclusive breast-feeding under well defined circumstances in developing countries.

 

Introduction

Feeding practices during infancy are of critical importance to the growth, development, and health of subjects during the first two years of life [1] and are also considered of importance in the early prevention of chronic degenerative diseases [2]. There are wide variations in available foods and dietary customs in different areas of the world, and patterns of breast feeding show important differences and changes with time. The prevalence and duration of breast-feeding have declined in many countries for a variety of social, economic, and cultural reasons [3, 4], although they have recently increased in many industrialized countries and in certain subgroups of the population in developing countries [5, 6].

A considerable controversy exists concerning the age at which human milk alone is no longer sufficient to support optimum growth and development of the infant [7-12]. The interpretation of observations is complicated by the varying supplementation of breast milk with other foods.

Various studies in Cuba have shown that, while a high proportion of mothers start breast-feeding their infants after delivery. the percentage of infants who continue to be exclusively breast-fed drops rapidly during the first four months [13, 14]. Foods other than milk are usually introduced at an early age in the Cuban population [13], and the timely introduction of solid foods is directly related to the mother's schooling [15] In a study of 218 infants grouped according to the mode of milk feeding, no significant differences were found in body weight or length at 6 and 12 months of age [16].

The present study is a contribution to the knowledge of current infant feeding practices in Cuba and the variations in growth with different patterns of milk feeding.

 

Subjects and methods

Feeding practices and growth were followed in 100 infants born during November 1987 to mothers living in the health areas of two of the municipalities of the city of Havana (Boyeros and 10 de Octubre) from the time of the child's discharge from the hospital until its first birthday.

All the deliveries occurred at the two maternity hospitals that serve the health areas under study. The sample consisted of 50 male and 50 female newborns, born consecutively in those hospitals after I November 1987, who fulfilled the following conditions: normal, full-term, weighing more than 2,500 g at birth, whose mothers were married, 20-30 years old, had had more than six years of schooling, and had received regular prenatal care at the primary health level. These criteria for sample selection contributed to some extent to diminish sources of variation that could influence physical growth.

Evaluations were made at discharge from the hospital, at 15 days of age, and every 15 days thereafter up to 360 days. In each evaluation, the mode of feeding, body weight, and body length were recorded. The information on mode of feeding included whether the baby was being breast-fed. bottle-fed, or both and any food other than milk that was being give at the time of the evaluation.

Anthropometric measurements were taken following the methodology of the International Biological Programme [17] and the Cuban National Child Growth Study [18]. Weight was measured in grams to the nearest 100 g on a Detecto scale; length was measured in centimetres to the nearest 0.1 cm using a Holtain infantometer. The body mass index (BMI; kg/m2) was calculated. The figures of BMI, weight and length for age, and weight for length were compared to the percentile distribution of Cuban reference values [18-20].

Mothers were asked their reason when they introduced bottle-feeding as a complement to breast feeding and again when the baby was weaned completely from the breast.

At the end of the study, the infants were grouped according to the mode and duration of milk feeding into three categories: (1) breast-fed for 90 days or more, (2) breast-fed for less than 90 days. and (3) bottle-fed from birth. Since the proportion of infants who were exclusively breast-fed for more than a few weeks was very low, the term "breast-fed" in these categories refers to those who received any breast-feeding, regardless of whether or not it was combined with bottle-feeding or other food (mixed feeding).

Mean values and standard deviations for weight, length, and BMI for each category and sex were calculated at 30 day intervals. Differences between groups were tested through one-way analysis of variance, Student's t test, and x2 tests.

 

Results

Table 1 shows the distribution of the infants according to the mode and duration of milk feeding.

At discharge from the maternity hospital (usually at two to three days of age), 77 newborns were exclusively breast-fed, 9 had mixed feeding, and 14 were bottle-fed. A rapid drop in exclusive breast feeding was observed: At 15 days of age 59 infants were exclusively breast-fed, 43 at 30 days, 24 at 60 days, and 12 at 90 days. None were exclusively breast-fed beyond 165 days. From a maximum number of 33 children with mixed feeding at 90 days, the number progressively dropped: 23 at 150 days. 21 at 180 days, 9 at 270 days, and 1 at 360 days.

Of the 86 infants who received their mothers' milk, 72 began receiving bottle-feeding as a complement to breast-feeding in the first year. This occurred before 90 days of age for 62 of the infants, and later for the remaining 10. The reasons given by the mothers appear in table 2. No significant differences were observed between those who introduced complementary milk feeding earlier and those who did so after 90 days.

Complete weaning from the breast occurred in 41 infants by 90 days of age. A comparison of the reasons for complete weaning in those weaned before 90 days with those weaned thereafter appears in table 3; differences between these two groups were not significant.

TABLE 1. Distribution of the sample of 100 intants according to sex and mode and duration of milk feeding

  Male Female Total
Breast-fed >90 days 24 21 45
Breast-fed <90 days 18 23 41
Bottle-fed from birth 8 6 14
Total 50 50 100

TABLE 2. Reasons given by mothers for introducing bottle feeding as a complement to breast-feeding according to age at introduction in 72 infants

 

<90 days

³ 90days

N

%

N

%

Not enough breast
milk

23

37.1

4

40.0

Infant was
unsatisfied

16

25.8

1

10.0

Doctor's
recommendation

13

21.0

3

30.0

Self decision

10

16.1

2

20.0

Total

62

100

10

100

TABLE 3. Reasons given by mothers for complete weaning from the breast according to age at weaning in 86 infants

 

<90 days

³ 90 days

N

%

N

%

Not enough breast
milk

16

39.0

10

22.2

Infant was
unsatisfied

9

22.0

12

26.7

Doctor's
recommendation

5

12.2

5

11.1

Mother's illness

5

12.2

4

8.9

Infant's illness

3

7.3

6

13.3

Infant dropped the
breast

2

4.9

7

15.6

Self decision

1

2.4

1

2.2

Total

41

100

45

100

 

Figure 1 shows the cumulative frequencies for groups of foods other than milk given to the babies under study. Eighty-two mothers were giving fruit juices to their babies at 15 days of age, and at 90 days all of them were. They also started feeding fruit purees very early; the cumulative frequency at 60 days was 71. Nearly a fourth offered mashed tubers such as malanga (taro) before 60 days, and 22 introduced meats (usually chicken or veal) from that age on. Though some of the mothers began to introduce egg yolk and cereals as early as 60 days, the cumulative frequencies did not rise as rapidly as for tubers and meats. Legumes were introduced later, but their use increased rapidly after 120 days. The cumulative frequency for leafy and yellow vegetables increased more slowly than for other foods, and almost half of the mothers were not feeding them to their infants even at 360 days.

No significant differences for weight, length, or BMI were found at 30 days of age - that is, at the beginning of the study - among the three groups.

Table 4 shows the means and standard deviations of length at 30, 90, and 360 days. No significant differences were observed among the, three groups at any stage of the study, though those who were bottle-fed from birth showed a tendency to be taller. Both male and female bottle-fed infants were sig nificantly heavier at 90 days of age than those breast fed 90 days or more, and the males were also significantly heavier than those breast-fed for less than 90 days (table 5). The differences between the bottle-fed group and those who were breast-fed 90 days or more remained significant for both sexes at 360 days.



FIG.1. Cumulative frequencies for the giving of foods of different groups to 100 infants at ages up to one year

 

TABLE 4. Mean body length of 100 infants according to sex and mode and duration of milk feeding

 

N

Length (cm)a

30 days

90 days

360 days

Males
(1) breast-fed >=90 days

24

56.1 (1.8)

61.3 (1.8)

75.1 (2.2)

(2) breast-fed <90 days

18

55.2 (1.6)

60.2 (2.1)

75.9 (2.8)

(3) bottle-fed from birth

8

54.9 (1.9)

60.4 (2.3)

76.4 (2.0)

Females
(1) breast- fed 390 days

21

54.8 (2.0)

57.8 (1.8)

74,0 (2.2)

(2) breast-fed <90 days

23

54.2 (1.9)

56.6 (2.6)

73.9 (2.0)

(3) bottle-fed from birth

6

54.9 (1.9)

59.1(2.6)

75.1 (2.3)

a. Data in parentheses are SDs.
Differences among groups or between pairs of groups are not significant.

TABLE 5. Mean body weight of l(N) infants according m sex and mode and duration of milk feeding

 

N

Weight (kg)

30 days

90 daysa

360 daysb

Males
(1) breast-fed 390 days

24

4.6 (0.8)

5.6 (0.9)

9.8 (0.6)

(2) breast-fed <90 days

18

4.4 (0.8)

5.2 (0.8)

10.2 ( 1.3)

(3) bottle-fed from birth

8

4.7 (0.6)

6.7 (1.0)

10.9 (0.6)

Females
(1) breast-fed 390 days

21

4.2 (0.6)

5.3 (0.5)

9.3 (0.7)

(2) breast-fed <90 days

23

4.1 (0,6)

5.1 (0.7)

9.3 ( 1.3)

(3) bottle-fed from birth

6

4.3 (0.8)

6.0 (1.1)

10.3 (0.8)

a. Males (1) - (3), p < .01; (2) - (3), p <.001 Females: (1) - (3). p < .05
b. Males and females: (1) - (3). p < .01.

 

Particularly interesting are the changes in the BMI. Bottle-fed males were significantly heavier in relation to length at 90 days than those from the other two groups. This difference diminished gradually with age, but they always showed significantly higher values than those breast-fed 90 days or more (fig. 2). For females, the trends were similar (fig. 3): At 90 days the bottle-fed infants were significantly heavier but no differences were found between the two groups of breast-fed infants. After 180 days the weight of those breast-fed 90 days or more decreased in relation to length, and the difference from those who were bottle-fed became more significant. Detailed data for BMI at 30, 90, and 360 days are given in table 6.

 

Discussion

The results show a pattern of low prevalence of exclusive breast-feeding and early weaning similar to that found in previous studies carried out in other population groups of Cuban infants [13, 14] despite the differences in time and sampling. In 1973 a cohort of 4,272 infants showed a rapid drop in breast-feeding prevalence - from 89.8%, at discharge from the maternity hospital to 39.9% at three months - and by that age more than two-thirds of the infants had started complementary feeding [13]. In 1984 Valdés et al. [14] followed up 1,483 infants born in a maternity hospital that serves two municipalities of downtown Havana and found the prevalence falling from 87.5% at discharge to 9.5% at three months.

The present sample was selected from infants born to mothers living in two municipalities with a high density of factories and a population mainly of workers, basically different from that of Valdés's study. Though the patterns are similar, the higher proportion of mothers still breast-feeding at three months could be due to the quality of the sample: educated, married women 20-30 years old who had undergone regular prenatal care. There is enough evidence to show that women with these characteristics in Cuba as in the United States, are more likely to breast-feed [21, 22].

The early initiation of complementary feeding by most mothers (introduction of other milk and solid foods as supplements to breast milk) made it difficult to segregate a group who were exclusively breast-fed (that is, who received breast milk as their only food except for fruit juices). Therefore the only difference between groups 1 and 2 was the duration of breast feeding. This would be expected to reduce any differences between the two groups.

No differences in length were found among the three groups of infants, but those who were bottle fed from birth (group 3) were heavier at 90 days than the two groups of "breast-fed" infants. This suggests a difference in fatness rather than in lean body mass. Overfeeding probably contributes to this result, since mothers add cereals, sugar, or other energy-dense foods to milk formula. In developing countries with adverse environmental factors bottle-feeding is more often associated with lower weights and a higher incidence of malnutrition than exclusive breast-feeding [8, 23]. On the other hand, children born into middle- and upper-income households. particularly when headed by an individual with at least some college education, are more likely to have been breast-fed than others. This has also been observed in Mexican-Americans [24].

TABLE 6. Body mass index (BMI) of 100 infants according to sex and mode and duration of milk feeding

  N BMI (kg/m2)
30 days 90 daysa 360 daysb
Males
(1) breast-fed ³ 90 days 24 15.1 (0 9) 16.0 (0 9) 17 8 (0.8)
(2) breast-fed <90 days 18 14.9 (1.0) 15.1 (1.2) 18.3 (1.5)
(3) bottle-fed from birth 8 15.1 (1.3) 17.8 (1.6) 19.1 (1.1)
Females
(1) breast-fed ³ 90 days 21 14.6 (0.7) 16.0 (0.9) 16.8 (0.8)
(2) breast-fed <90 days 23 14.4 (0.8) 15.7 (0.9) 17.9 (1.0)
(3) bottle-fed from birth 6 14.8 (1.2) 17.0 (1.0) 18.3 (0.9)

a.Males:(1)-(3) and (2) - (3) , p<.001. Females: (1)-(3), p<.05; (2)-(3), p<.01.
b.Males:(1)-(3),p<.01.Females:(1) (3) and (1) (2).p<.001.



FIG. 2. Means and standard deviations of body mass index in 50 male infants grouped according to mode of milk feeding. Different letters indicate significant differences in mean values at different ages.



FIG. 3. Means and standard deviations of body mass index in 50 female infants grouped according to mode of milk feeding. Different letters indicate significant differences in mean values at different ages.

 

In the present study. environmental factors were good and rather homogeneous, and no differences in illness experience were observed among groups during the follow-up. Thus, the mean values for length. weight, and BMI of the three groups were between the 25th and 75th percentiles of the Cuban standards [18, 19].

The age at which milk formula and solid foods should be introduced to a breast-fed infant has been a matter of discussion because it depends on the adequacy of breast milk alone to fulfil the infant's energy and nutrient requirements. Exclusive breast feeding can be adequate for varying periods from 2 months in some underprivileged mothers to 15 months in exceptional cases; there is no fixed age at which it becomes inadequate [25, 26]. In several studies [10, 11], a catch-up growth has been observed after the supplementation of the diets of apparently well-nourished infants with formula or solid foods at three months of age. It is evident that there are individual differences in energy and nutrient needs, but a general recommendation is to give breast milk as the only food up to the fourth month and then to introduce solid foods gradually while continuing breast-feeding.

There is no doubt that the initiation of weaning is a critical event in an infant's life. It is closely linked to the mother's opinion that breast milk has become insufficient for the baby, as observed in this study and in other reports [13, 14, 27-29]. Unfortunately, very little progress has been made in educating mothers on how to increase breast milk output for prolonged and successful breast-feeding. This requires much greater attention.

Since no initial differences were observed among the three groups studied and the family environments were rather uniform, the apparent associations found between the mode of milk feeding and body weight appear to have been due to differences in food intake.

 

Acknowledgements

The authors are gratefully indebted to the neonatal services of the Enrique Cabrera and II) de Octubre hospitals and to the departments of paediatrics of the municipalities of Boyeros and 10 de Octubre for their contributions to this study.

 

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