Yes, feeding while lying down is associated with ear infection. It allows fluid and germs to travel more easily from the back of the throat to the middle ear. Fluid, formula or milk in the middle ear can act as a culture medium, basically growing the germs that cause ear infections. Also, during sleep the natural rinsing action of saliva diminishes, allowing baby's teeth to be bathed in the sugary milk or formula, leading to decay. However, breastfeeding while lying is not associated with this problem since it has added characteristics that strengthen the baby's immunity.