A slightly higher than normal body temperature is common during pregnancy because of the hormone progesterone and increased metabolism. On the other hand, an infection or illness can cause your body temperature to increase too much, causing harm to you and your unborn baby. Consult your physician if your temperature is abnormally high, especially if it is accompanied by additional symptoms like chest congestion.
Basal Body Temperature
Your basal body temperature is your resting body temperature. The average basal body temperature is 98.6 degrees Fahrenheit. The best time to take your basal body temperature is when you first wake up in the morning before you get out of bed. Your BBT can be monitored orally, vaginally or rectally. For consistency, take your BBT at the same time every morning, using the same method.
Luteal Phase and Progesterone
Your menstrual cycle includes the preovulation, or follicular, phase and the luteal phase, which is the two weeks following ovulation. During the luteal phase, your body releases the hormone progesterone, which increases your basal body temperature up to one degree higher than preovulation temperatures. When you are pregnant, your body continues to release progesterone, causing your BBT to stay elevated. However, your BBT shifts closer to your preovulation temperatures as your pregnancy progresses, according to the University of Tennessee's Center for Physical Activity & Health.
To meet the demands of pregnancy, your blood volume, heart rate and metabolism increase, resulting in a higher basal body temperature. To prevent overheating, your superficial blood vessels, which are close to the surface of your skin, dilate to release some of the heat. Symptoms include flushed red skin, sensitivity to heat, increased sweating and hot flashes, which are common and normal during pregnancy.
A temperature that is 101 degrees F or higher is considered a fever and indicates an infection or illness, according to the Organization of Teratology Information Specialists. A fever during pregnancy can be caused by the flu, urinary tract infection, and other bacterial and viral illnesses. Additional symptoms include pain while urinating, nausea, vomiting, headache, chest congestion and runny nose. A prolonged fever during pregnancy may increase the risk of a miscarriage and birth defects. Therefore, consult your physician immediately if you have an abnormally high temperature or a temperature above 101 degrees F.
Your slightly elevated body temperature can also be the result of your lifestyle and activities during pregnancy. Stress, insomnia, exercise, hot humid weather and caffeinated beverages can increase your body temperature. To prevent overheating, avoid hot and humid environments like hot tubs, layer your clothing, exercise in well-ventilated areas, perform yoga to reduce stress and avoid consuming caffeinated beverages like coffee.
- Organization of Teratology Information Specialists; Hyperthermia and Pregnancy; August 2010
- University of Cincinnati Clermont College, Biology 105; Reproductive Physiology, Conception, Prenatal Development; J. Stein Carter
- “American Family Physician”; Exercise During Pregnancy; Thomas W. Wang, M.D., et al.; April 1998
- “Motherwell Maternity Fitness Plan”; Bonnie Berk; 2005