Infants have limited ability to use thermoregulation (A) because of the development of the capillary beds. Capillary beds are networks of small blood vessels that are responsible for delivering oxygen and nutrients to the body's tissues. In newborns and infants, the capillary beds are not fully developed, which means that they are less effective at regulating body temperature. As a result, infants are more susceptible to hypothermia and other temperature-related conditions. To help maintain body temperature, infants may need to be placed in incubators or other temperature-controlled environments. Over time, as the capillary beds develop, infants will gain a greater ability to regulate their body temperature.