Date Published: August 27, 2019
Publisher: Public Library of Science
Author(s): Brian Houle, Tamsen J. Rochat, Marie-Louise Newell, Alan Stein, Ruth M. Bland, Kathleen Rasmussen
Abstract: BackgroundEvidence on the association between breastfeeding and later childhood obesity and blood pressure (BP) is inconsistent, especially in HIV-prevalent areas where, until recently, HIV-infected women were discouraged from breastfeeding, but obesity is increasingly prevalent.Methods and findingsThe Siyakhula cohort (2012–2014), a population-based prospective cohort study, collected data over 3 visits on HIV-negative children ages 7 to 11 years in rural South Africa. We used weight (body mass index [BMI]), fat, and BP as outcome variables and incorporated early life (including mother’s age at delivery and HIV status) and current life factors (including maternal education and current BMI). Our primary exposure was breastfeeding duration. We dichotomized 3 outcome measures using pre-established thresholds for clinical interpretability: (1) overfat: ≥85th percentile of body fat; (2) overweight: >1 SD BMI z score; and (3) prehypertension: ≥90th percentile for systolic BP (SBP) or diastolic BP (DBP). We modelled each outcome using multivariable logistic regression, including stopping breastfeeding, then early life, and finally current life factors. Of 1,536 children (mean age = 9.3 years; 872 girls; 664 boys), 7% were overfat, 13.2% overweight, and 9.1% prehypertensive. Over half (60%) of the mothers reported continued breastfeeding for 12+ months. In multivariable analyses, continued breastfeeding between 6 and 11 months was associated with approximately halved odds of both being overfat (adjusted odds ratio [aOR] = 0.43, 95% confidence interval [CI] 0.21–0.91, P = 0.027) and overweight (aOR = 0.46, CI 0.26–0.82, P = 0.0083), but the association with prehypertension did not reach statistical significance (aOR = 0.72, CI 0.38–1.37, P = 0.32). Children with a mother who was currently obese were 5 times more likely (aOR = 5.02, CI 2.47–10.20, P < 0.001) to be overfat and over 4 times more likely to be overweight (aOR = 4.33, CI 2.65–7.09, P < 0.001) than children with normal weight mothers. Differences between HIV-exposed and unexposed children on any of the outcomes were minimal and not significant. The main study limitation was that duration of breastfeeding was based on maternal recall.ConclusionsTo our knowledge, this is the first study examining and quantifying the association between breastfeeding and childhood obesity in an African setting with high HIV prevalence. We observed that breastfeeding was independently associated with reduced childhood obesity for both HIV-exposed and unexposed children, suggesting that promoting optimal nutrition throughout the life course, starting with continued breastfeeding, may be critical to tackling the growing obesity epidemic. In the era of widespread effective antiretroviral treatment for HIV-infected women for life, these data further support the recommendation of breastfeeding for all women.
Partial Text: Prevention and treatment of noncommunicable diseases (NCD), such as obesity and hypertension, to reduce premature mortality is a critical target of the Sustainable Development Goals . Approximately 70% of premature deaths in 2013 were attributed to NCDs , and an estimated 82% of premature deaths occurred in low- and middle-income countries (LMIC) . Adopting a life course approach to NCD prevention, the importance of early life exposures, including optimal nutrition for the child in the first 1,000 days of life, the onset of risk factors in childhood and adolescence, and their links to NCDs in later life have been highlighted [4–6].
Ethics permission was granted by the Biomedical Research Ethics Committee, University of KwaZulu-Natal, South Africa (BF184/12). This study is reported as per the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guideline (S1 Checklist). The Siyakhula cohort was established in 2012 at the Africa Health Research Institute (AHRI; formerly the Africa Centre for Population Health), in rural KwaZulu-Natal, South Africa, including 7 to 11 year-old HIV-negative children of HIV-positive and HIV-negative mothers . AHRI operates a demographic surveillance system (DSS) in 11,000 homes twice yearly , with data collected including births, deaths, SES, and adult HIV status. Children in the Siyakhula cohort were from 2 sources as has been previously described in detail by Rochat and colleagues . Approximately half of the cohort children had participated (from birth to age 2 years) in a breastfeeding study, the VTS (2001–2006) . The primary aim of the VTS was to determine the effect of infant feeding practices on vertical transmission of HIV infection; mothers were supported to exclusively breastfeed. The results demonstrated that exclusive breastfeeding was associated with a reduced risk of mother-to-child transmission of HIV compared with mixed breastfeeding [48,49]. The second group of children were enrolled from the DSS; these children were born during the same VTS time period but did not participate in the VTS and thus had not been exposed to infant feeding support. It is important to note that all eligible children within the DSS were approached for inclusion in the Siyakhula cohort—some of whom had participated in the VTS and others who had not. The Siyakhula cohort predated antiretroviral treatment roll-out in the country. It thus allows for examination of outcomes associated with HIV exposure without antiretroviral treatment (ART) exposure (which is associated with potential neurotoxicity and neurodevelopmental consequences in early childhood ) in utero and during breastfeeding. Early life data are available for all Siyakhula children from either the DSS, VTS, or both. Data from the DSS includes factors routinely collected during biannual collection rounds, and information from the VTS includes information collected during the 2 years of data collection [47,48]. Available early life data includes birth order, birth weight, mother’s age at birth, and mother’s HIV status. Information on child anthropometry were collected with the aim of examining the effect of early life factors on later outcomes ; we did not have a specific analysis plan prior to data collection. All research at AHRI was conducted with permission from the local health authorities. Any participants requiring medical care were referred to the local clinics or the hospital in the subdistrict that had a paediatric ward.
Fig 1 shows the participant flowchart of the Siyakhula cohort: 1,592 of a possible 2,515 children were enrolled; 1,536 children completed assessments (477 HIV-exposed, 1,057 HIV-unexposed (278 HIV-affected)); the mothers of 2 children had missing HIV status. Detailed comparisons of eligible, enrolled, and completed subgroups are presented elsewhere .
To our knowledge, this is the first study examining breastfeeding, obesity, overweight, and BP in HIV-exposed and unexposed school-aged children in Africa. Seven percent of 7 to 11 year-old children were overfat, 13% overweight, and 9% prehypertensive in this rural, high HIV prevalence setting in South Africa. Our finding that sustained breastfeeding beyond 6 months is associated with approximately halved odds of being overfat and overweight at ages 7 to 11 years, irrespective of maternal HIV status and allowing for early and current life factors, is important given the increasing obesity epidemic, particularly in resource-poor settings, including those with high HIV prevalence . Our finding reinforces the current WHO guidelines on sustained breastfeeding for HIV-infected women on ART , bringing the breastfeeding guidelines in line with those for uninfected women. Although we are unaware of studies examining overfatness in South African children, results from the PROMISE-EBF trial in South Africa showed that early nonbreastfeeding was associated with obesity at 2 years but this study excluded children of HIV-positive mothers . Our findings are consistent with data from large cohorts in high-income countries [8,13,17,18] and with a meta-analysis  estimating a 4% decreased risk of being overweight for each month of breastfeeding up to 9 months of age, which may be important at a population level. In an updated meta-analysis  of breastfeeding and later outcomes over a wide age range, breastfed children were reported to be less likely to be overweight and obese (pooled OR = 0.74; 95% CI 0.7–0.78). Among the high-quality studies included, breastfeeding was associated with an estimated 13% reduction in being overweight or obese in childhood .
To our knowledge, this is the first study examining breastfeeding and childhood obesity in an African setting with high HIV prevalence. HIV has impacted breastfeeding guidelines over several decades [61,65,86–88], with confused and mixed messages about infant feeding and erosion of breastfeeding practices . With the advent of ART for life, breastfeeding is recommended in many settings for HIV-positive women for at least 12 months and up to 24 months or longer . Although evidence generally supports a protective association between breastfeeding and later overweight in childhood , it is important to examine this association in HIV-prevalent settings, particularly because breastfeeding rates may be less than optimum. We confirm and quantify the association, finding that breastfeeding for at least 6 months was associated with half the odds of being overfat and overweight in children aged 7 to 11 years; the association with BP, although in the same direction, did not reach statistical significance. Children of HIV-positive and HIV-negative mothers had similar outcomes in terms of their body fat, BMI, and BP. Breastfeeding has benefits that extend into midchildhood and should be highlighted, for both HIV-exposed and -unexposed children, as one of the strategies to tackle adult obesity and the associated public health consequences of ill health, including diabetes, hypertension, and cancer.