Trend and correlation of obesity and continued breastfeeding in children from six to 3 months old

Abstract Objectives: to analyze the trend and correlation of obesity and the increase in continued breastfeeding in children aged six to 23 months in Brazil, from 2015-2019. Methods: ecological time series study with data from the Sistema de Vigilância Alimentar e Nutricional (Food and Nutritional Surveillance System). The dependent variable was the prevalence of obesity. Prais-Winsten linear regression was used to verify the trend. Spearman’s correlation was used to verify the relationship between the prevalence of obesity and the increase in continued breastfeeding. Results: there was a trend towards a reduction in the prevalence of obesity in all regions in Brazil (Annual Percentage Variation [APV]: -4.14; CI95%=-4.50; -3.79). The prevalence of continued breastfeeding showed an upward trend in the North (APV=4.89; CI95%=2.92; 6.90), Southeast (APV=3.36; CI95%=2.32; 4 .41) and South (APV=2.67; CI95%=0.98; 4.38). There was a negative and significant correlation between obesity and continued breastfeeding in the North, Northeast, Southeast and South regions. Conclusion: the reduction in the prevalence of obesity and the increase in continued breastfeeding occurred only in some regions, requiring the implementation of effective strategies to be present throughout the country. Actions to promote, protect and support continued breastfeeding and healthy eating should be more prioritized to promote the child’s healthy growth.


Introduction
Childhood obesity has shown an increasing concern among Brazilian children in recent decades, from 1990 to 2010, becoming a public health challenge. 1Overweight is a difficult condition to treat.Recognizing the protective or modifiable risk factors is a key aspect to prevent obesity and the development of diseases such as cancer and type 2 diabetes in childhood, conditions that may persist into adulthood, besides causing morbidity and mortality from heart disease. 2 Children are the most affected by the ingestion of unhealthy food, because during childhood nutritional necessities are increased and both the scarcity and inadequate quality of food can trigger major health problems, such as low immunity, learning disabilities, increased infections, obesity, and in many situations, death. 3Thus, childhood is a decisive period in relation to human health, especially when it comes to nutrition. 3,4pto six months of age, breast milk is the ideal food for every child because of its nutritional composition, being rich in proteins, fat, and vitamins. 5From six months to two years of age or beyond, continued breastfeeding (CBF) is recommended, 6 a factor that seems to have a significant effect on nutritional control throughout life. 7Continued breastfeeding provides several benefits to the child, such as protection against infectious diseases, especially gastrointestinal and respiratory diseases, and reduces the chances of dyslipidemia, obesity, and diabetes. 8Estimates from other studies show that continued breastfeeding could prevent, on average of 820,000 deaths in low-and middle-income countries. 8he Sistema de Vigilância Alimentar e Nutricional (SISVAN) (Food and Nutrition Surveillance System) can be used to support early prognosis, 9 because it is a relevant source to promote greater assertiveness in planning actions and assist in the development of nutrition and food activities for the population assisted in local, state, and federal levels. 10n this context, it is important to analyze aspects related to children's health for a better elaboration of strategies and early health policies, 11 especially regarding eating habits and nutritional status.The recognition of the importance of breastfeeding for nutritional status in childhood and the relevance of adequate coverage of SISVAN to support the diagnosis of food and nutritional status at childhood 12 justify this investigation.
The article aimed to analyze the trend and correlation of obesity and BMI in children aged six to 23 months followed up in primary health care services in Brazil from 2015 to 2019.

Methods
This is an ecological observational time series study conducted in Brazil, from 2015 to 2019, whose units of analysis were the Unidades Federativas (UF) (Federative Units).SISVAN data about the nutritional status and food consumption of children aged six to 23 months assisted in the primary health care services linked to the Sistema Único de Saúde (SUS) (Brazilian Public Health System) were used.SISVAN is publicly accessible and data are obtained through electronic reports via the web. 13he following filters were used to obtain the following indicators: (a) nutritional status (obesity prevalence): reference For the time trend analysis, the Prais-Winsten linear regression model was applied to estimate the annual percent change (APC) in the prevalence of obesity and CBF and their 95% confidence intervals (CI95%).The trends were considered increasing when p<0.05 and positive regression coefficient, decreasing when p<0.05 and negative regression coefficient, and stable when p>0.05.15 Spearman correlation was used to check for a monotonic relationship between obesity (dependent variable) and CBF (independent variable), considering a 5% significance level.
The distribution of the averages of obesity and CBF prevalence by UF was presented on maps built in the QGIS 2.18.23 Las Palmas program.
There was no submission to the Research Ethics Committee (CEP), because it is a study using a secondary database, available on public access websites, without any identification of the participants.
The highest mean prevalences of obesity were concentrated in the States of the Northeast region, being highest in Sergipe (14.01%),Ceará (12.46%), and in the prevalence of obesity inversely proportional to the increase in the prevalence of CBF in the North, Northeast, Southeast, and South regions.

Discussion
The results of this research showed that children on CBF had better results of nutritional status assessed according to BMI, compared to children who did not continue breastfeeding after six months of life.At childhood, obesity can occur due to endogenous factors, such as hereditary problems, or exogenous, of behavioral, dietary, and/or environmental origin.The habits of family members or other individuals in the social environment in which the child lives and mirrors itself can influence children's eating habits. 16ombating childhood obesity can prevent chronic non-communicable diseases in adulthood such as cardiovascular accidents and diabetes, as well as orthopedic problems, dyslipidemia, hypertension, sleep apnea, gout, cancer, and psychological problems. 17For this reason, the detection of overweight early in life is important, because it allows early interventions and prevention of future complications.The longer the obesity persists, the more difficult it will be for the treatment and the incorporation of new habits. 18hus, monitoring the development and growth of children from birth and especially in the first year of Prevalence CBF by FS

Figure 1
Mean prevalence (%) of obesity and continued breastfeeding in children aged six to 23 months followed up in primary care.Brazil, 2015-2019.
Source: Food and Nutrition Surveillance System.life becomee essential. 19It is during this phase that early weaning and/or the inappropriate introduction of complementary foods, both in quality and quantity, occurs.Moreover, early introduction of food is also associated with increased risk of malnutrition, more episodes of diarrhea, and poor absorption of relevant nutrients from breast milk, 19 in addition to obesity. 18orldwide, between 1980 and 2014, the proportion of obese individuals more than doubled. 20According to WHO, by 2020, about 40 million children under five years of age were identified as obese, and 340 million adolescents and children between five and 19 years of age were obese or overweight. 21 survey of children up to one year of age living in New York City (U.S.A) 22 found that 11.2% of the group investigated were considered obese.In a study conducted at Duke University with children and adolescents aged 2 to 19 years old on the prevalence of obesity and severe obesity, it was observed that the most prominent rates were found in adolescents, although an increase in severe obesity was observed among children aged 2 to 5 years old.23 It is projected that Brazil, in 2030, will occupy the fifth position in the ranking of countries with the highest percentage of adolescents and children with obesity, with little chance of reversing the picture.In a study conducted in 2019, nationwide, the prevalence of obesity in children under five years old was 10.1%.The region with the lowest prevalence was the Midwest (7.1%), which showed a statistically significant difference compared to the South, the region with the highest prevalence (12.0%).21 Regarding children under two years of age, the states located in the Northeast region showed the highest percentages of obesity, especially Sergipe (14.4%),Ceará (11.8%), and Maranhão (11.2%).24 Despite the reduction in the prevalence of obesity found in this study, the Northeast region, especially the Sates of Sergipe, Ceará, and Maranhão, had the highest rates on obesity. Ths finding can be explained by the socioeconomic status of families, which is a determining factor for childhood obesity, influencing people's attitudes, especially in the choice and purchasing food.11 Families with low socioeconomic conditions tend to offer food with high glycemic index through ultra-processed and processed food, rich in calories, fat and sugar.This socioeconomic context sedentifies and harms the child, making it evident that the social reality can characterize a blockage to meet the nutritional necessities of children with low financial status. 2 The stability in the prevalence of CBF in children aged six to 23 months old when comparing regions in the period of 2015 to 2019 suggests an important factor to be analyzed.It is likely that there is an association between dose-response and duration of CBF, that is, the longer the breastfeeding period of the individual, the lower the possibility of developing obesity and/or overweight.19 Despite the close relationship between CBF and obesity found in this study, there was no significant relationship in most UF in Brazil.This condition may be explained by the fact that the study considered age groups starting at 6 months of age, as, children who were already able to receive complementary feeding, and other Variables, could favor weight gain and reduce the influence of breastfeeding.25 The study was carried out with 566 children living in a city of São Paulo in the period 2004-2005 recognized that both CBF for six months or more and as CBF for 24 months or more constitute a protective factor against obesity and overweight.24 A research done by WHO on the evidence of the protective effect of breastfeeding in the long term showed that children with continuous breastfeeding were 22 times less likely to be obese and/or overweight.26 The probable mechanisms that reduce the risk of obesity and/or overweight in breastfed children are due to the action of bioactive compounds present in human milk that, when associated with protein intake, promote satiety regulation.In addition, breast milk contains leptin, a hormone that acts directly on energy balance and appetite regulation, which contributes to protection against overweight and obesity in breastfed children.25 This study showed a negative correlation between CBF and obesity in almost all regions of Brazil, suggesting that breastfeeding works as an early protection factor in the prevention of obesity.Infants who are breastfed seem to have a greater ability to self-regulate food intake, which may be important for the establishment of healthy patterns of appetite regulation, favoring self-control of food intake according to needs.On the other hand, bottle-feeding and complementary feeding, administered by a caregiver, insensitive to the hunger and satiety signals emitted by the child, may favor overfeeding, consequently increasing the risk of childhood overweight and obesity.27 This study presented limitations because it is a survey with secondary data, susceptible to errors due to registration or typing errors and possible underreporting.Moreover, the results should be cautiously evaluated due to the ecological fallacy, in other words, one cannot make causal inferences regarding individuals based on group observations, 28 given the heterogeneous distribution of exposure and outcome variables within the groups themselves.However, despite the potential limitations, the study design allows us to obtain inferences at the population group level and contribute to strengthen actions to protect and monitor child health in Brazil.
Despite the downward trend in childhood obesity found in all the regions in Brazil, it is necessary to maintain and implement other effective actions for its reduction because of the serious consequences of this problem.

Figure 1
Figure 1 Mean prevalence (%) of obesity and continued breastfeeding in children aged six to 23 months followed up in primary care.Brazil, 2015-2019.

Table 1
Prevalence trend (%) of obesity in children aged six to 23 months followed up in primary care.Brazil, Regions and Federative Units (UF), 2015 to 2019.
a Annual Percentage Variation; b 95% Confidence Interval; c Wald's Test.Source: Food and Nutrition Surveillance System.

Table 2
Prevalence trend (%) of continued breastfeeding (CBA) in children aged six to 23 months followed up in primary care.Brazil, Regions and Federative Units (UF), 2015 to 2019.

Table 3
Correlation between prevalence (%) of obesity and prevalence of continued breastfeeding according to regions in Brazil, 2015 to 2019.