Lactation consultants and leading breastfeeding advocacy organizations tell new mothers that newborns who nurse frequently will get enough milk, and that a newborn doesn’t need much milk in the first few days of life. But it’s estimated that up to 15 percent of moms don’t produce enough milk, due to complex factors including genetics, and newborns who aren’t fed sufficiently can develop dehydration, low blood pressure, and hypoglycemia (low blood sugar), which can cause irreversible brain injury and, in rare cases, death. Insufficient supply in the first days after birth, before milk “comes in,” is more common in first-time mothers.