Lactation of suckling by the baby. The milk ejection reflex (also called let-down reflex) is not always consistent, especially at first. Once a woman is conditioned to nursing, let-down can be triggered by a variety of stimuli, including the sound of any baby. Even thinking about breastfeeding can stimulate this reflex, causing unwanted leakage, or both breasts may give out milk when an infant is feeding from one breast. However, this and other problems often settle after two weeks of feeding. Stress or anxiety can cause difficulties with breastfeeding. The release of the hormone oxytocin leads to the "milk ejection" or
Human milk microbiome in mature milk. Taxonomic composition of human milk also varies across the lactation period, initially dominated by "Weisella, Leuconostoc, Staphylococcus, Streptococcus," and "Lactococcus" species, and later composed primarily of "Veillonella, Prevotella, Leptotrichia, Lactobacillus, Streptococcus, Bifidobacterium," and "Enterococcus" Human milk oligosaccharides, a primary component of human milk, are prebiotics which have been shown to promote growth of beneficial "Bifidobacterium" and "Bacteroides" species. Mode of delivery may influence composition of the human milk microbiome, vaginal births being associated with high taxonomic diversity and high prevalence of "Bifidobacterium" and "Lactobacillus," and the opposite trend being seen with Cesarean births, however, no relationship between