Subfebrile temperature in pregnant women

Subfebrile temperature in pregnant women: Normal or hidden infection?

Subfebrile temperature is a persistent elevation of body temperature in the range of 37.1°C to 38.0°C. For a pregnant woman, this condition can be either an absolute normal or the first, barely noticeable signal of a hidden inflammatory process. Understanding the physiological reasons for subfebrility during pregnancy helps avoid unnecessary anxiety, while still not missing a situation that requires a doctor's attention.

Physiological subfebrility: The role of progesterone

In the first trimester of pregnancy, a slight temperature rise to 37.2‑37.4°C is very common and completely normal. The main "culprit" is the hormone progesterone. Its level rises sharply, and one of its systemic actions is an effect on the thermoregulation center in the hypothalamus, leading to a modest increase in basal body temperature. This physiological subfebrility usually is not accompanied by a worsening of well‑being and is only an indicator of intensive hormonal remodeling.

When should subfebrile temperature raise concern?

Although a mild temperature rise is normal, persistent subfebrility, especially when combined with other symptoms, may indicate a hidden inflammatory process. It can be:

• Asymptomatic bacteriuria or chronic urinary tract infection.
• Hidden infection focus: chronic tonsillitis, dental problems.
• Exacerbation of chronic viral infections (cytomegalovirus, Epstein‑Barr virus).
• General fatigue and exhaustion. More details in the article "Fatigue during pregnancy".

If subfebrile temperature persists for a long time, is accompanied by weakness, malaise, or any other symptoms, it is necessary to inform a doctor and undergo additional examinations, including submitting blood and urine tests. Read about general mechanisms in the article "Subfebrile temperature".