I wouldn't be surprised if this temperature change is the result of the known 20 percent to 30 percent increase in blood flow in a pregnant woman. Their body temperature may rise when they are exposed to heat or when they are overdressed. And newborns are particularly prone to hypothermia, or low body temperature, when exposed to cold or when they are inadequately dressed. One cause for the tendency toward hypothermia is their large surface area in comparison to body weight. Heat loss occurs through the skin, so a relatively large surface area increases this process.
Several factors contribute to changes in body temperature with age.
Average body temperature probably tends to fall because of a less-active metabolism. Also, older individuals tend to be less physically active. Both of these factors can predispose someone to hypothermia. In addition, the sweat glands are less active and require higher body temperatures to trigger the sweating mechanism. This may make older individuals more prone to heat exhaustion as well.