Feeling unusually cold or experiencing sudden chills is a common symptom reported during the first trimester of pregnancy. These sensations can range from a persistent chill to abrupt shivers. The body undergoes rapid transformation to support the pregnancy, and these physiological shifts impact temperature regulation. Understanding the mechanisms behind these cold spells can provide reassurance that this fluctuation is a normal part of early pregnancy.
The Physiological Reasons Behind Cold Chills
The sudden sensation of coldness often stems from the body’s internal thermostat being reset by a surge of pregnancy hormones. Progesterone, which is released in high amounts to sustain the uterine lining, acts directly on the hypothalamus in the brain. The hypothalamus is the body’s control center for thermoregulation, and this hormonal action effectively raises the basal body temperature set point by a small fraction, typically around 0.5°C.
To reach this new, higher temperature, the body initiates mechanisms that can include shivering or a sensation of chilliness. The increased metabolic rate required to support the pregnancy also demands more energy and generates heat, but this heat is not always distributed evenly.
Circulatory changes also contribute to the feeling of coldness, particularly in the extremities. The body begins to prioritize blood flow to the core and the developing uterus, which can temporarily reduce circulation to the hands and feet. This shift in blood volume and distribution, coupled with hormonal influence on blood vessels, creates a sudden feeling of coldness or mild shivers. This temporary imbalance often resolves as the body’s total blood volume increases significantly later in pregnancy.
Differentiating Normal Chills from Fevers
It is important to distinguish between the normal, hormone-related chills of early pregnancy and those that signal an infection. Normal chills occur without a sustained elevation of core body temperature. They are sensations of coldness or shivers that typically pass and are not indicative of illness.
Chills accompanied by a true fever require prompt attention because they suggest the presence of an underlying infection, such as influenza, a urinary tract infection (UTI), or another viral illness. A temperature of 100.4°F (38°C) or higher is clinically considered a fever in pregnancy. If a person measures their temperature and it reaches this threshold, or if they experience persistent, severe chills, they should contact a healthcare provider immediately.
Fevers, especially those reaching 101°F or higher, should not be ignored during pregnancy, as the underlying infection could pose risks. Other warning signs to watch for alongside chills include pain, weakness, extreme fatigue, or flu-like symptoms. A healthcare provider will determine the cause of the fever and recommend appropriate, safe treatment to manage the infection.
Managing Body Temperature Fluctuations
Since the chills are often a result of the body’s new temperature regulation process, simple comfort measures can help manage the daily fluctuations. A practical strategy involves dressing in multiple, light layers of clothing. This allows for quick adjustments as the body cycles between feeling chilled and warm.
Maintaining adequate hydration is beneficial for temperature regulation. Consistent intake of nutritious meals supports metabolic demands and helps stabilize warmth. Controlling the immediate environment, such as using extra blankets or adjusting the thermostat, provides comfort against unexpected cold spells.