Breastfeeding And Feeding Patterns In Three Birth Cohorts In Southern Brazil Trends And Differentials

ARTIGO ARTICLE S409

Breastfeeding and feeding patterns in three
birth cohorts in Southern Brazil: trends and
differentials

Amamentação e padrões alimentares em três
coortes de nascimento no Sul do Brasil: tendências
e diferenciais

Cesar G. Victora 1
Alicia Matijasevich 1
Iná S. Santos 1
Aluisio J. D. Barros 1
Bernardo L. Horta 1
Fernando C. Barros 2

Abstract Introduction

1 Programa de Pós-gradu-
Breastfeeding is fundamental for child health. Breastfeeding plays an important role in child
ação em Epidemiologia,
Universidade Federal de Changes in the duration of breastfeeding are development, especially as a protective factor
Pelotas, Pelotas, Brasil. compared for three population-based cohorts against infectious diseases 1,2. In addition to such
2 Programa de Pós-graduação
of children born in 1982, 1993 and 2004 in the protection, breastfeeding also increases child
em Saúde e Comportamento,
Universidade Católica de city of Pelotas, Southern Brazil. Samples of the spacing 3,4 and promotes ideal child growth 5.
Pelotas, Pelotas, Brasil. 1982 and 1993 children and all of the children Recent results also suggest that breastfeeding
from the 2004 cohort study were sought at home may contribute to intellectual development, as
Correspondence
C. G. Victora when they were aged around 12 months. Both well as to the prevention of various chronic dis-
Programa de Pós-gradu- the duration of breastfeeding and the stage at eases in adult life 6. The promotion of exclusive
ação em Epidemiologia,
which different kind of foods were regularly in- breastfeeding is the single intervention with the
Universidade Federal de
Pelotas. troduced were investigated. The median dura- greatest potential to reduce under-five mortality
Rua Marechal Deodoro 1160, tion of breastfeeding increased from 3.1 to 6.8 worldwide 7.
3 o andar, Pelotas, RS
96020-220, Brasil.
months in this period. Exclusive breastfeeding The duration of breastfeeding in Brazil was
cvictora@terra.com.br at three months was practically non-existent extremely short in the 1970s and 1980s. A nation-
in 1982 and had reached one third of infants by wide survey carried out in 1975 showed that the
2004. The increase was faster after 1993, suggest- median duration of total breastfeeding was only
ing an important impact made by promotion 74 days 8. A series of interventions were imple-
activities. Up to about 6-9 months, breastfeed- mented beginning in the 1980s, which led to im-
ing was more prevalent in high-income fami- portant increases in the duration of breastfeed-
lies, but after this age it became more common ing during the 1990s 8,9.
among the poor. Low birth weight babies were Although a number of studies on breast-
breastfeed for shorter durations. The duration feeding have been conducted in Brazil, it is also
of breastfeeding is still far short of internation- important to analyze trends among different so-
al recommendations, justifying further cam- cioeconomic and birth weight strata. The pres-
paigns. Special attention should be given to low ent analysis evaluates changes in the duration of
birth weight babies and those from low-income breastfeeding in the city of Pelotas, Rio Grande
families. do Sul State, Brazil, based on three longitudinal
studies of the mother-child population that be-
Breast Feeding; Child Welfare; Cohort Studies gan in 1982, 1993, and 2004.

Cad. Saúde Pública, Rio de Janeiro, 24 Sup 3:S409-S416, 2008

S410 Victora CG et al.

Methods poses of comparison, the prevalence of exclusive
breastfeeding in 1982 was considered as null.
As part of the Pelotas birth cohort studies, we In each of the three cohorts, at least 1,300 chil-
evaluated all hospital births that took place in dren were included in the analyses. The margin
1982, 1993, and 2004. The methodology used in of error for estimating the prevalence of breastfed
these studies has been described elsewhere 10. children at each age was equal to or less than 2.5
Mothers were interviewed soon after delivery and, percentage points.
among other variables, provided information on We used the chi-squared test to measure as-
total family income, which was calculated as the sociations between independent variables (sex,
sum of individual incomes in the month preced- family income, and birth weight) and the dura-
ing the interview. All children were weighed using tion of breastfeeding. Whenever possible, we
calibrated pediatric scales. used the linear trend test to study trends between
At the beginning of 1983, we attempted to the three cohorts.
locate all children living in urban areas born be- Statistical analysis was carried out using Sta-
tween January and April 1982, who were then ta software (Stata Corp., College Station, USA) to
an average 12 months old. In the 1993 cohort, calculate the percentage of breastfed children at
a sample of births was followed at ages six and different ages and to estimate the median dura-
12 months, including all low birth weight chil- tion of breastfeeding based on life tables.
dren (< 2,500g) and a systematic sample of ap-
proximately 20% of the remaining children. Final
results were weighted so as to reproduce the pro- Results
portion of low birth weight in the general popula-
tion observed in the perinatal study. In 2004, we In 1983, we traced 1,556 (81.8%) of the 1,820
attempted to locate all children around the time children born between January and April 1982,
of their first birthday. who were on average 11.2 months old (standard
In the three studies, mothers responded to deviation 1.3 months). In 1993, we were able to
a household questionnaire administered by in- trace 93% of children at age 12 months. In 2004,
terviewers who received prior training and were the follow-up rate was 94% 10.
educated to at least high-school level. Between We found an increase in the median dura-
five and 10 per cent of interviews were repeated tion of breastfeeding from 3.1 months in 1982
by a supervisor for quality control purposes. The to 4.0 months in 1993 and 6.8 months in 2004
questionnaire included questions on the dura- (Table 1). Figure 1 shows that, although initially
tion of breastfeeding and the ages at which differ- almost all children from the three cohorts were
ent types of foods were introduced on a regular breastfed, an increase in breastfeeding in the
basis. Weaning was defined as the total interrup- more recent cohorts was already evident after
tion of breastfeeding. the first month (linear trend test p < 0.001 in the
To avoid recall bias, comparisons of weaning first month and at ages 3, 6, 9, and 12 months).
age and introduction of complementary feeding The greatest increase occurred between the 1993
were based on data collected when children were and 2004 cohorts.
approximately 12 months old. Figure 2 shows the feeding pattern of children
The feeding patterns of children during the at three and 12 months of age. Important prog-
first year of life were classified into four groups: ress was seen at age three months. In 1982, al-
(i) exclusive breastfeeding - breastfed children though specific information on the consumption
that were not fed any other fluids or solid foods; of tea and water had not been collected, the prac-
(ii) predominant breastfeeding - breastfed chil- tice of exclusive breastfeeding was virtually null.
dren that were also fed other fluids, such as water Such practice could already be observed in 1993,
or tea, but who were not fed solid or semi-solid when 7% of children were exclusively breastfed.
foods; (iii) partial breastfeeding - children that In 2004, this proportion increased to 31% (χ2 p
were fed breast milk complemented with other < 0.001). Predominant breastfeeding was seen in
types of milk, such as cow’s milk or formula, or 34% of children in 1982, 41% in 1993, and 17% in
with solid or semi-solid foods; and (iv) weaning 2003; such a reduction seems to have been due
- children that were not breastfed. to the increase in exclusive breastfeeding. Con-
In 1982, there was not a specific question re- sidering all types of breastfeeding, 54%, 62%, and
garding the ingestion of tea or water, since this 73% of three-month-old children were breastfed
was a universal practice at the time, with all chil- in 1982, 1994, and 2004, respectively (χ2 for linear
dren being given tea and water soon after birth. trend p < 0.001).
The advantages of exclusive breastfeeding be- Figure 2 also shows that, at age 12 months,
came evident only in the late 1980s 11. For the pur- 18%, 23%, and 39% of children were still breast-


BREASTFEEDING AND FEEDING PATTERNS S411

Table 1

Median duration of breastfeeding according to sex, family income, and birth weight. Pelotas, Southern Brazil, 1982, 1993,
and 2004.

Variables Median duration of breastfeeding (months)
1982 1993 2004

Sex NS p < 0.001 p = 0.04
Male 3.0 3.8 6.5
Female 3.2 4.3 7.4

Family income (minimum wage) p = 0,8 p = 0.5 p = 0.05
≤ 1.0 2.9 3.9 5.8
1.1-3.0 2.9 4.1 7.0
3.1-6.0 3.3 3.7 6.8
6.1-10.0 3.6 3.6 7.8
> 10.0 3.4 5.3 6.9

Birth weight (g) p < 0.05 p < 0.0001 p < 0.001
< 2,000 1.8 1.4 3.7
2,000-2,499 2.1 3.1 5.7
2,500-2,999 3.0 4.0 6.8
3,000-3,499 3.0 4.1 7.2
≥ 3,500 3.5 4.5 6.8

Total 3.1 4.0 6.8

NS: non-signiﬁcant.

Figure 1

Percentage of breastfed children at different ages. Pelotas, Southern Brazil, 1982, 1993, and 2004.



Figure 2

Breastfeeding patterns at age 3 and 12 months. Pelotas, Southern Brazil, 1982, 1993, and 2004.

%

fed in 1982, 1993, and 2004 (χ2 for linear trend p the three studies, with a surprisingly short dura-
< 0.001). tion among the < 2,000g group, which was par-
However, feeding practices varied between tially reversed in 2004 (Table 1). Breastfeeding
different subgroups of children. Breastfeeding increased throughout the two-decade period
lasted longer for girls than for boys in 1993 and across all breastfeeding groups.
2004 (Table 1). There were no marked differenc-
es in terms of median duration between family
income groups (Table 1). However, as shown in Discussion
Figure 3, there were some interesting changes
among the poorer (people earning less than or The existence of three population-based cohort
equal to the minimum wage) and richer (those studies allowed for breastfeeding patterns to be
earning more than 10 times the minimum wage) compared across a 22-year time period. The per-
strata. In the three cohorts, the richest group centage of follow-up at age 12 months increased
showed a greater prevalence of breastfeeding from 79% in 1982 to 94% in 2004 due to the inno-
up to age six months but was overtaken by the vative strategies used in tracing subjects 10.
poorest group between six and nine months, so We observed an important increase in the
that, at age 12 months, poor mothers breastfed median duration of breastfeeding, from 3.1
more than rich mothers. Also noteworthy is the months in 1982 to 6.8 months in 2004. 1982 levels
observation that the increase in breastfeeding were compatible with those observed throughout
frequency at ages one, three, and six months oc- the country in that period 8, but the median in
curred between 1982 for the richest group and 2004 is similar to the 7.0 month median reported
between 1993 and 2004 for the poorest. By con- in 1996 for the entire country (7.1 months in the
trast, the increase at age 12 months took place South Region, in which Pelotas is located) 8,12. In
between 1993 and 2004 for both poor and rich 1999, a nationwide survey of state capitals was
groups. conducted during a vaccination campaign 13,
We found a direct relationship between which resulted in an estimate of 9.9 months for
birth weight and duration of breastfeeding in all Brazilian capitals and 7.5 months for those in



Figure 3

Percentage of breastfed children at different ages in the extreme income strata. Pelotas, Southern Brazil, 1982, 1993, and 2004.

Family income
(minimum wage/year)

the South Region, which is similar to the median half of all children in Pelotas were breastfed at
obtained for Pelotas in 2004. their first birthday.
The analysis of feeding patterns (Figure 2) Countless factors influence the decision
shows that this increase is due to the increase of whether or not to breastfeed, hindering the
in exclusive breastfeeding during the first few evaluation of the impact of breastfeeding pro-
months of life, when its protective effects are motion programs. Notwithstanding, the present
greater 1,14, as well as to an increase in partial data support a possible impact of the Brazilian
breastfeeding during the second semester. National Breastfeeding Program, that has been
The introduction of fluids other than breast carried out since 1981 across the entire coun-
milk during the first months of life is not only un- try 9,16,17. Rea 9, in an analysis of breastfeeding
necessary – since exclusively breastfed children promotion activities throughout Brazil, showed
do not need additional water – but it may also be that interventions begun in the 1980’s were sub-
deleterious 15. The introduction of other fluids stantially reinforced after 1996, with the training
may lead to a decreased frequency and intensity of large numbers of health workers for support-
of suction, thus reducing breast milk produc- ing breastfeeding, backed-up by protection pol-
tion. There is also the risk of infections due to icies. In Pelotas, specifically, a number of train-
the contamination of bottles or of the food itself. ing courses were offered to primary healthcare
Moreover, the premature introduction of certain professionals, and the first “Baby-Friendly” hos-
types of foods, such as cereals or vegetables, may pital was opened in the city. The present results,
interfere with iron absorption, leading to iron de- which show an acceleration of the increase in
ficiency. Long-term risks, such as obesity, hyper- breastfeeding duration after the 1993 cohort,
tension, arteriosclerosis, and food allergies may are entirely compatible with the chronogram
also be associated with the introduction of other described by Rea 9.
foods and weaning 6. Data from the three cohorts confirm previous
The World Health Organization and United findings 18,19 regarding biological and socioeco-
Nations Children’s Fund also recommend that nomic differentials in breastfeeding. Gender dif-
partial breastfeeding be continued until age 2 ferences in breastfeeding have been reported by
years 11. However, in 2004, only 39% of children others. In the present study girls were breastfed
were breastfeed at 12 months. Despite the sub- longer than boys, a finding also reported by other
stantial progress in the last decade, still less than authors 20. Children from low-income families



or with low birth weight, who most need breast- a similar increase took place between 1993 and
feeding, are those that receive less breast milk 2004. This may be evidence that an increase in
during the first months of life. The shorter du- breastfeeding occurred earlier among the rich.
ration of breastfeeding among low birth weight Regarding the increase in the percentage of
babies has been described previously 4. Morbid- breastfed children at 12 months, both the rich
ity and mortality in low birth weight children is and the poor showed greater increases predomi-
greater among formula-fed than among breast- nantly after 1993, which may reflect the fact that
fed babies 21. the importance of breastfeeding during the sec-
Results regarding family income show a ond semester of life has been emphasized only
paradoxical relationship. High-income moth- more recently.
ers breastfeed more during the first months of The susceptibility of breastfeeding to adver-
life than do low income mothers. This period of tisements for artificial feeding is a well-known
life is exactly when children are at greater risk phenomenon. Between the 1950s and 1970s,
of morbidity and mortality, especially those when incentives for using formula feeding were
from poor families, as shown in other articles in substantial and there were no restrictive health
the present supplement 22,23. Premature wean- policies regarding such advertisements, the
ing among these children may be contributing duration of breastfeeding fell substantially in
to the increase in mortality and morbidity. On several countries 25. More recently, campaigns
the other hand, there is a greater prevalence of encouraging breastfeeding and valuing breast
breastfeeding among poor children at nine and milk led to the reversion of falling trends not on-
12 months of age. ly in Brazil 9 but also in Latin America 26. Despite
In a previous publication, we proposed the these changes, the duration of breastfeeding,
hypothesis of inverse equity, that is, that inno- especially exclusive breastfeeding, remains sub-
vations in health tend to reach the rich before stantially lower than international recommen-
they reach the poor, thereby potentially increas- dations, which reinforces the need to continue
ing social inequities 24. Figure 3 shows that, in the stimulating this practice in the first months of
highest income group, the increase in the per- life. The present results also suggest that spe-
centage of breastfed children at ages one, three, cial care must be devoted to the promotion of
and six months occurred mostly between 1982 breastfeeding among lower income strata and
and 1993. Among the poor, on the other hand, for children with low birth weight.



Resumo Contributors

A amamentação é fundamental para a saúde infantil. C. G. Victora designed the research question, super-
O artigo compara mudanças na duração da amamen- vised the analysis and interpretation of the findings as
tação em três coortes de nascimentos, de 1982, 1993 e well as wrote the first draft of the article. A. Matijasevich
2004, na cidade de Pelotas, Rio Grande do Sul. Amos- conducted the analysis and with I. S. Santos, A. J. D.
tras das coortes de 1982 e 1993 e todas as crianças da Barros, B. L. Horta and F. C. Barros contributed to the
coorte de 2004 foram visitadas em casa em torno de interpretation of the analyses and assisted with the edit-
12 meses de idade. Foram investigados a duração da ing of the article.
amamentação e o momento em que diferentes tipos
de alimentos foram introduzidos na dieta regular. A
duração mediana da amamentação aumentou de 3,1
para 6,8 meses ao longo do período. O aleitamento ex-
clusivo aos três meses era praticamente inexistente em
1982, mas alcançou um terço dos lactentes em 2004. O
aumento foi mais expressivo a partir de 1993, sugerin-
do um impacto importante das atividades de promo-
ção. Até aproximadamente 6-9 meses, a amamentação
era mais prevalente em famílias de renda mais alta,
mas depois dessa idade passava a ser mais comum en-
tre famílias mais pobres. Crianças com baixo peso ao
nascer apresentavam menor duração de amamenta-
ção. A duração da amamentação está aquém das reco-
mendações internacionais, o que justifica a realização
de mais campanhas nesse sentido. Deve-se concentrar
mais atenção nos recém-nascidos de baixo peso e na-
queles de famílias de baixa renda.

Aleitamento Materno; Bem-Estar da Criança; Estudos
de Coortes

References

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Submitted on 29/Mar/2007
Final version resubmitted on 07/Nov/2007
Approved on 09/Jan/2008


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