Abstract
Expressed Breast Milk (EBM) is increasingly used throughout the developed world. In 2013, it was estimated that ∼25% of mothers in the United States express regularly their milk, and close to 40% do it occasionally, whereas most of the 6 million pumps sold annually are mostly purchased in North America and Europe. 1 EBM is the preferred nutrition of the sick infant unable to feed directly at the breast, and in particular, the fragile preterm infant hospitalized in the Neonatal Intensive Care Unit. In such infants, the exclusive use of EBM and human milk (HM) products has been shown to minimize the risks of necrotizing enterocolitis2,3 and sepsis.3,4 For this purpose, over the past few decades, HM banks have been established in many countries throughout the world. EBM is also used increasingly by mothers of healthy infants for multiple reasons. Some are fully aware of the health benefits of HM and do not want to expose their babies to animal-based formulas even after they have returned to work after the (unfortunately too short) maternity leave of absence provided by the legislation of most countries in the world. 5 Others wish to include caretaker partners, primarily a spousal partner. 1
Many manipulations are required for the handling of EBM and vary in terms of methods of collection and storage. At times sterilization is required to eliminate potential microbiological threats that may fundamentally modify not only contents but also biological properties of HM.
In this special issue of Breastfeeding Medicine, we have asked several experts to write state-of-the-art reviews related to the effects of biologic and environmental determinants on HM composition. The group led by Dr. Bhatia described factors affecting the composition of expressed fresh HM. In this specific article, Pham et al. review the effects of maternal diet and medications, as well as those of milk expression, handling, and storage on major constituents of breast milk. The group led by us (Yochpaz et al.) performed a systematic review and meta-analysis of the effect of freezing and thawing on HM macronutrients and energy composition. The article by Dr. Riskin is devoted to the immunomodulatory constituents of human donor milk and to what is known about their regulation. In addition, we have also included articles accepted in the journal that were specifically related to the general topic of this issue. Palnizky Soffer et al. address the issue of the impact of maternal anxiety on HM macronutrients content. Chang et al. report the effect of processing of donor milk on its nutrient and energy content. Finally, the article by Aparici-Gonzalo et al. is devoted to a new and original field of research, that of the effect of mode of delivery on the melatonin content of HM.
We hope that the readers of Breastfeeding Medicine will enjoy this special issue. As time goes by, scientific knowledge on breastfeeding and breast milk accumulates at a fast pace. In view of the amount of knowledge we still do not have, research on breastfeeding appears to be a truly humbling but highly rewarding experience.