Many sources suggest a general increase in body warmth during pregnancy, yet it is common for pregnant individuals to report feeling chilled. The body’s temperature regulation system undergoes profound adjustments to support the developing fetus. These internal shifts mean that while the overall core temperature may be elevated, the sensation of coldness can occur locally or intermittently. Understanding the underlying biology helps distinguish between a normal physiological shift and a symptom that warrants medical attention.
How Pregnancy Affects Core Body Temperature
The baseline core body temperature of a pregnant person is typically elevated, a physiological change that begins almost immediately after conception. This sustained warmth is primarily driven by the hormone progesterone, which has a known thermogenic effect. This effect maintains a higher basal body temperature throughout gestation, similar to the temperature rise seen during the menstrual cycle.
The body’s entire metabolism also increases substantially to support the growth of the fetus and the placenta, generating more heat. Furthermore, pregnancy requires an expansion of the circulatory system, increasing the total blood volume by up to 50%.
This higher volume of circulating blood contributes to the body’s overall heat capacity, pushing the core temperature upward. The body counteracts this internal heat by becoming highly efficient at cooling itself, often through increased blood flow to the skin and enhanced sweating.
Causes of Localized Cold Sensations
Despite the general increase in core temperature, many pregnant individuals experience localized coldness, particularly in the hands and feet. This occurs because the body prioritizes blood flow to the central organs and the uterus to ensure fetal development. The circulatory system redistributes blood away from the extremities, a process known as peripheral vasoconstriction, which causes these areas to feel cold.
This shunting of blood to the body’s core is a normal adjustment, but it leaves the limbs more sensitive to the external environment. Temporary chills can also follow a sudden cooling-off period, especially after an episode of sweating or feeling overheated. The body’s efficient cooling mechanisms can sometimes overshoot, leading to a rapid drop in skin temperature that results in a momentary shiver or chill.
Another factor contributing to intermittent cold sensations is the fluctuation in blood pressure, which often drops during the first and second trimesters. This drop is due to hormonal changes that relax blood vessel walls. When blood pressure is lower, the heart must work harder to circulate the increased blood volume, and a temporary dip can result in symptoms like cool, clammy skin.
Persistent Coldness and Potential Health Concerns
While temporary chills and cold extremities are common, persistent or severe cold intolerance affecting the entire body may signal an underlying health issue. One common cause of chronic coldness is anemia, a condition characterized by a deficiency of healthy red blood cells needed to transport oxygen. Anemia is prevalent due to the increased demand for iron to support expanded blood volume and fetal growth.
When oxygen delivery is compromised, the body’s tissues, including those in the extremities, can feel cold. Anemia often presents with symptoms such as fatigue, paleness, and a weak or rapid pulse.
Another potential cause is an underactive thyroid gland, or hypothyroidism, which slows the body’s overall metabolic rate. Since the thyroid controls energy use and heat production, a deficiency in its hormones leads directly to cold intolerance. Hypothyroidism may also cause fatigue, constipation, and weight gain, symptoms which can be mistaken for normal pregnancy discomforts.
If a person experiences unusual or long-lasting coldness, especially when accompanied by other systemic symptoms, it is important to consult a healthcare provider. A simple blood test, such as a complete blood count (CBC) or a thyroid-stimulating hormone (TSH) test, can help determine if anemia or a thyroid disorder is the source of the persistent cold feeling.