Feeling cold or having chills during pregnancy is a common experience, and it is a natural result of the significant physiological changes happening within the body. Pregnancy alters the body’s internal thermostat, known as thermoregulation, causing fluctuations that can make a person feel warmer than usual at times, but unexpectedly chilly at others. These temperature shifts reflect the body’s constant adjustment to the demands of nurturing a developing fetus. Understanding the underlying mechanisms can help distinguish normal sensations from signs that might require medical attention.
The Physiology of Temperature Fluctuations
The hormone progesterone plays a significant role in altering the body’s temperature set point. This hormone is thermogenic, meaning it tends to raise the core body temperature slightly, similar to the temperature rise seen after ovulation in a non-pregnant cycle. However, the body’s attempt to regulate this sustained, higher baseline can sometimes lead to sudden drops in temperature, resulting in coldness or chills.
The body’s metabolic rate also increases substantially to support the growth of the fetus and the placenta. This increased metabolism generates excess heat, often making the pregnant person feel warm. When this increased heat production slows, such as during periods of rest or inactivity, the resulting rapid cooling can trigger a feeling of being chilled.
Circulatory changes also contribute to temperature fluctuations, particularly in the extremities. Blood volume increases dramatically during pregnancy, by up to 50%, but a large portion of this blood is redirected to the uterus and the skin’s surface for heat dissipation. This redistribution of blood flow can lead to reduced circulation in the hands and feet, which may feel perpetually cold even when the rest of the body is warm. The body prioritizes blood flow to the core and the fetus.
Anemia and Other Specific Cold Triggers
While hormonal and circulatory changes are normal parts of pregnancy, persistent coldness can sometimes signal a treatable underlying issue. Iron-deficiency anemia is a common cause, affecting many pregnant people as the increased blood volume dilutes the concentration of red blood cells. Iron is necessary for hemoglobin production, which transports oxygen throughout the body; a deficiency impairs this transport, reducing the body’s ability to generate and conserve heat.
Other factors involving energy and circulation can also trigger spells of coldness or chills. Low blood sugar, or hypoglycemia, can occur when the body’s energy demands are high, and this dip in glucose can sometimes manifest as sudden chills or shivering. Hormonal changes that relax blood vessel walls can lead to low blood pressure, or hypotension, which slows circulation and can cause symptoms like fatigue, dizziness, and a cold feeling.
Differentiating Chills from Fever
It is important to distinguish between benign chills, which are often related to hormonal shifts, and chills that accompany a true fever, which may indicate an infection. A fever is defined as a sustained, measurable elevation of body temperature, typically reaching 100.4°F (38°C) or higher. Chills, or shivering without a temperature rise, are an uncomfortable, but harmless, side effect of the body’s thermostat resetting.
Chills that are followed by a temperature reading of 100.4°F or more should prompt a call to a healthcare provider. A fever is not an expected symptom of pregnancy and may signal an infection, such as a urinary tract infection or the flu.
Signs that warrant immediate medical attention include a fever accompanied by:
- Severe abdominal pain.
- A stiff neck.
- Difficulty breathing.
- Pain or burning during urination.
- Persistent vomiting and diarrhea, as they can quickly lead to dehydration.
Practical Strategies for Comfort
To manage the common, non-fever-related temperature fluctuations, simple adjustments can significantly improve comfort. Layering clothing is an effective strategy, allowing for easy addition or removal of garments as the body temperature shifts throughout the day. Using blankets or socks to warm up cold extremities can also provide quick relief from peripheral chilliness.
Maintaining a steady intake of fluids is beneficial for temperature regulation and overall circulation. Consuming a balanced diet helps prevent sudden dips in blood sugar that can trigger cold spells. If anemia is a concern, ensuring adequate iron intake through diet or supplements, as recommended by a healthcare provider, can directly address cold sensitivity.