RESUMEN
Introduction: Growth patterns of breastfed and formula-fed infants differ, but the influence of breastfeeding duration on early growth remains unclear. The objective of this study is to evaluate current evidence on the association of exclusive and partial breastfeeding duration with different growth parameters during infancy. Materials and Methods: In this systematic review, we searched MEDLINE, EMBASE, and additional sources from January 2011 until March 2018 to identify relevant cohort studies and randomized controlled trials (RCTs). Results: Twenty studies that recruited infants from the general population were included. In the developed setting, exclusive breastfeeding duration was inversely associated with weight and length gain during infancy in observational studies. Longer duration of exclusive breastfeeding was also associated with an earlier peak in infant body mass index (BMI). Inconsistent results were observed for the associations of exclusive breastfeeding duration with other infant BMI characteristics. In an RCT conducted in Iceland, exclusive breastfeeding for 4 versus 6 months did not affect infant growth patterns. In the developing setting, conflicting findings on the associations of exclusive breastfeeding duration with infant weight and length parameters were shown in observational studies. Shorter partial breastfeeding duration was associated with higher weight gain during infancy, with limited or inconclusive data regarding other growth parameters. Conclusions: Longer duration of exclusive and partial breastfeeding tended to be associated with slower growth rates during infancy in the developed setting only. These associations seem to be dose dependent and more pronounced in exclusively versus partially breastfed infants.