Just as your temperature is a bit higher during the second half of the menstrual cycle (due to elevated levels of the hormone progesterone), your temperature may be a bit higher during pregnancy—but not much. We must get rid of extra heat generated by the baby during pregnancy, but the feeling of being warm is part of the mechanism to eliminate that heat.
Our bodies work on a thermostat system. We have a set point that we aim for—when we are well, that is around 98.6 Fahrenheit. Without conscious effort, we will get rid of extra heat when necessary—by flushing, which is when blood flows to the skin to get cooler, and by sweating, which is cooling as it evaporates. In addition, feeling warm makes us want to change the environment to cool off. The opposite mechanisms apply when we are cold—blood flows away from the skin into the body’s warm core, and we shiver, which creates heat.
When we are ill, our thermostat set point changes, and the body “tries” to warm up. While your set point is above your body temperature you feel cold, maybe experiencing chills, and you want to get under several blankets. Once the fever “breaks,” your set point is below your current temperature, and your body kicks in to “I’m too hot” mode, flushing and sweating and kicking off the covers. The set point during pregnancy is not significantly higher than it is during the second half of the menstrual cycle, but you may feel warm as your body works to eliminate the heat made by the baby. Fever is not normal in pregnancy and should be treated with Tylenol® and evaluated by a doctor or midwife if it is very high or persistent.