Exclusive breastfeeding and cognition, executive function and behavioural disorders in primary school-aged children in rural South Africa: a cohort analysis

Background: exclusive breastfeeding (EBF) is associated with early child health; longer-term benefits for child development remain inconclusive. We examine associations between EBF, HIV exposure, and other maternal/child factors, with cognitive and emotional-behavioural development in children aged 7-11 years.Methods and findings: the Vertical Transmission Study (VTS) supported EBF in HIV-positive and negative women; between 2012-2014 HIV-negative VTS children (332 HIV-exposed, 574 HIV-unexposed) were assessed on cognition (KABC-II), executive function (NEPSY-II), and emotional-behavioural functioning (CBCL). We developed population means by combining the VTS sample with 629 same-aged HIV-negative children from the local Demographic Platform. For each outcome we split the VTS sample into scores above or at/below each population mean and modelled each outcome using logistic regression analyses, overall and stratified by child sex. There was no demonstrated effect of EBF on overall cognitive functioning. EBF was associated with fewer conduct disorders overall (aOR0.44 [95%CI 0.3-0.7] p<=0.01) and there was weak evidence of better cognition for boys who had EBF for 2-5 months vs ?1 month (Learning sub-scale aOR2.07 [95%CI 1.0-4.3] p=0.05). Other factors associated with better child cognition were higher maternal cognitive ability (aOR1.43 [95%CI 1.1-1.9] p=0.02 Sequential, aOR1.74 [95%CI 1.3-2.4] p<0.001 Planning sub-scales) and crèche attendance (aOR1.96 [95%CI 1.1-3.5] p=0.02 Sequential sub-scale). Factors positively associated with executive function were home stimulation (aOR1.36 [95%CI 1.0-1.8] p=0.04 Auditory Attention, 1.35 [95%CI 1.0-1.8] p=0.05 Response Set) and crèche (aOR1.74 [95%CI 1.0-3.0] p=0.05 Animal Sorting). Maternal mental health problems and parenting stress were associated with increased emotional-behavioural problems on the total Child Behaviour Checklist (CBCL) (aOR2.44 [95%CI 1.3-4.6] p=0.01; aOR7.04 [95%CI 4.2-11.9] p<0.001 respectively). Maternal HIV status was not associated with any outcomes in the overall cohort. Limitations include the non-randomised study design and lack of maternal mental health assessment at the child’s birth. Conclusions: EBF was associated with fewer than average conduct disorders, and weakly with improved cognitive development in boys. Efforts to improve stimulation at home, reduce maternal stress, and enable crèche attendance are likely to improve executive function and emotional-behavioural development of children