The uncontrollable shivering and shaking many people experience shortly after giving birth is a common physiological event known as postpartum chills or rigors. This temporary phenomenon, characterized by involuntary muscle contractions, can feel intense and surprising. Postpartum chills are experienced by a significant number of new mothers and are considered a normal, temporary bodily reaction to the immense stress and changes of childbirth. The shaking typically begins within the first two hours following delivery and usually resolves on its own within minutes, though it can occasionally last up to an hour.
The Role of Hormones and Adrenaline
The sudden shift in the body’s internal chemistry is a primary driver of the postpartum shakes. During pregnancy, hormones like estrogen and progesterone surge to high levels, helping to sustain the pregnancy and regulate the body’s systems. Once the baby and the placenta are delivered, these levels plummet almost immediately. This rapid hormonal freefall can significantly impact the body’s internal thermostat, leading to a temporary dysregulation of temperature control.
Furthermore, the physical and emotional intensity of labor triggers a massive release of stress hormones, including adrenaline and noradrenaline, as part of the “fight or flight” response. These hormones increase heart rate, blood pressure, and metabolic activity to help cope with the exertion of birth. After delivery, the body experiences a sudden “crash” as the need for this high level of adrenaline abruptly ends. The resulting shift in the nervous system can manifest as uncontrollable shivering and muscle contractions.
Physical Stressors and Temperature Regulation
Beyond the hormonal changes, the physical demands of labor and the immediate environment contribute significantly to the shaking. Labor is a profound physical event that consumes massive amounts of energy, which can lead to extreme exhaustion and muscle fatigue. This maternal exhaustion can sometimes present as tremors as the muscles react to the strenuous work they have just performed.
Thermoregulation, the body’s process of maintaining a stable internal temperature, is frequently disrupted in the delivery setting. The body often sweats profusely during labor, and exposure to the cooler ambient temperatures common in delivery suites can cause a rapid drop in skin temperature. To counteract this heat loss, the body initiates shivering as a mechanism to quickly generate heat through muscle activity.
Medical interventions often play a role in altering core body temperature. Many women receive large volumes of intravenous (IV) fluids during labor; if these fluids are administered at room temperature, they can contribute to a temporary lowering of the body’s core temperature. Epidural anesthesia can also affect temperature regulation by causing vasodilation, which opens up blood vessels on the skin and increases heat loss, making the body more susceptible to the shivering response.
When Shaking Signals a Problem
While postpartum shaking is usually a harmless, transient event that disappears quickly, it is important to distinguish it from shaking that signals a medical concern. Normal postpartum chills are typically short-lived, resolving completely within about 20 to 60 minutes, and are not accompanied by other severe symptoms.
A persistent or severe shivering that lasts for many hours, especially when paired with a fever, may indicate an infection. A temperature of 100.4°F (38°C) or higher can be a sign of a postpartum infection, such as endometritis. This combination of fever and intense chills warrants immediate medical evaluation.
Shaking can also accompany a postpartum hemorrhage, a serious condition characterized by heavy blood loss. Signs that the shaking is related to a hemorrhage include:
- Soaking through one or more sanitary pads in an hour.
- Passing large blood clots.
- Experiencing dizziness or lightheadedness.
- Having a fast or irregular heartbeat.
Any shaking accompanied by severe pain, foul-smelling vaginal discharge, or overwhelming feelings of general illness should be promptly reported to a healthcare provider for a thorough assessment.