title: Effects of early feeding on growth velocity and overweight/obesity in a cohort of HIV unexposed South African infants and children.
abstract: BACKGROUND
  South Africa has the highest prevalence of overweight/obesity in Sub-Saharan Africa. Assessing the effect of modifiable factors such as early infant feeding on growth velocity and overweight/obesity is therefore important. This paper aimed to assess the effect of infant feeding in the transitional period (12 weeks) on 12-24 week growth velocity amongst HIV unexposed children using WHO growth velocity standards and on the age and sex adjusted body mass index (BMI) Z-score distribution at 2 years.
  
  
  METHODS
  Data were from 3 sites in South Africa participating in the PROMISE-EBF trial. We calculated growth velocity Z-scores using the WHO growth standards and assessed feeding practices using 24-hour and 7-day recall data. We used quantile regression to study the associations between 12 week infant feeding and 12-24 week weight velocity (WVZ) with BMI-for-age Z-score at 2 years. We included the internal sample quantiles (70th and 90th centiles) that approximated the reference cut-offs of +2 (corresponding to overweight) and +3 (corresponding to obesity) of the 2 year BMI-for-age Z-scores.
  
  
  RESULTS
  At the 2-year visit, 641 children were analysed (median age 22 months, IQR: 17-26 months). Thirty percent were overweight while 8.7% were obese. Children not breastfed at 12 weeks had higher 12-24 week mean WVZ and were more overweight and obese at 2 years. In the quantile regression, children not breastfed at 12 weeks had a 0.37 (95% CI 0.07, 0.66) increment in BMI-for-age Z-score at the 50th sample quantile compared to breast-fed children. This difference in BMI-for-age Z-score increased to 0.46 (95% CI 0.18, 0.74) at the 70th quantile and 0.68 (95% CI 0.41, 0.94) at the 90th quantile . The 12-24 week WVZ had a uniform independent effect across the same quantiles.
  
  
  CONCLUSIONS
  This study demonstrates that the first 6 months of life is a critical period in the development of childhood overweight and obesity. Interventions targeted at modifiable factors such as early infant feeding practices may reduce the risks of rapid weight gain and subsequent childhood overweight/obesity.
authors: Health Systems Research Unit, South African Medical Research Council, Cape Town, South Africa ; Centre for International Health, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.
authors: Vundli
authors: V
authors: Ramokolo
authors: Biostatistics Unit, South African Medical Research Council, Cape Town, South Africa.
authors: Carl
authors: C
authors: Lombard
authors: Centre for International Health, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway ; School of Public Health, University of the Western Cape, Cape Town, South Africa ; Department of Pediatrics, University of KwaZulu Natal, KwaZulu Natal, South Africa.
authors: Meera
authors: M
authors: Chhagan
authors: Centre for International Health, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.
authors: Ingunn Ms
authors: IM
authors: Engebretsen
authors: Health Systems Research Unit, South African Medical Research Council, Cape Town, South Africa ; School of Public Health, University of the Western Cape, Cape Town, South Africa.
authors: Tanya
authors: T
authors: Doherty
authors: Health Systems Research Unit, South African Medical Research Council, Cape Town, South Africa ; Department of Paediatrics and Child Health, Kalafong Hospital, University of Pretoria, Pretoria, South Africa.
authors: Ameena E
authors: AE
authors: Goga
authors: Centre for International Health, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway ; Department of Clinical Dentistry, University of Bergen, Bergen, Norway.
authors: Lars Thore
authors: LT
authors: Fadnes
authors: Health Systems Research Unit, South African Medical Research Council, Cape Town, South Africa.
authors: Wanga
authors: W
authors: Zembe
authors: School of Public Health, University of the Western Cape, Cape Town, South Africa.
authors: Debra J
authors: DJ
authors: Jackson
authors: Centre for International Health, Department of Global Public Health and Primary Care, University of Bergen, Bergen, Norway.
authors: Jan
authors: J
authors: Van den Broeck