A heated blanket is an electrical appliance containing insulated wires that generate warmth for comfort, typically used in bed or while resting. Moderate and cautious use of a heated blanket during pregnancy is generally considered low risk for the developing baby. However, safety depends entirely on avoiding one potential danger: significantly raising the pregnant person’s internal body temperature. The primary concern is the excessive heat it might produce, requiring careful control of usage.
The Primary Concern: Core Body Temperature Rise
The main physiological risk associated with external heat sources during pregnancy is hyperthermia, a sustained elevation of the core body temperature. Medical guidelines identify a core temperature exceeding 101°F (38.3°C) as concerning, with temperatures above 102°F (38.9°C) for an extended period being particularly worrisome. This risk is most pronounced during the first trimester, when the fetus is undergoing organogenesis, the formation of its major organs and structures.
A sustained high core temperature, such as that caused by a fever, hot tub, or sauna, has been associated with an increased risk of specific birth complications. Research points to a connection between maternal hyperthermia in early pregnancy and the development of neural tube defects (NTDs) of the brain and spinal cord. While heated blankets are less likely to cause hyperthermia than immersion in a hot tub, prolonged use on a high setting can still potentially push the core temperature past the safe threshold.
Heated blankets primarily warm the surface of the body and the bedding, unlike a hot tub which immerses the entire body in heat. This distinction means the blanket’s heat is less efficiently transferred to the mother’s core, making it less of a direct threat. However, if heat is trapped and the body’s natural cooling mechanisms are overwhelmed, the internal temperature can still rise. Therefore, the duration and intensity of the heat exposure are the determining factors for maintaining a safe environment.
Understanding Electromagnetic Fields
Beyond the thermal concern, a common question involves the non-thermal risk associated with heated blankets: exposure to Electromagnetic Fields (EMFs). Heated blankets utilize electrical current to generate warmth and produce low-level, non-ionizing radiation. This is a characteristic shared by many household appliances, including computers, hair dryers, and cell phones.
The electromagnetic fields emitted by these blankets are of an extremely low frequency and are not considered high-energy radiation like X-rays. Current scientific research does not show a definitive link between typical, low-level EMF exposure from household sources and adverse reproductive outcomes. Major health organizations conclude that the evidence does not confirm that typical environmental EMF exposure increases the risk of birth defects, miscarriage, or low birth weight.
Many modern heated blankets are designed with technology that minimizes EMF exposure. For individuals who remain concerned, the scientific consensus is that any theoretical risk from EMFs is far less significant than the recognized danger of overheating. Therefore, the primary focus for safety remains on temperature control rather than eliminating the low-level electromagnetic energy.
Guidelines for Safe Use and Alternatives
Safe use of a heated blanket during pregnancy focuses entirely on minimizing the risk of core body temperature elevation. The most recommended approach is to use the blanket solely for pre-warming the bed before getting in. The blanket should be turned off and unplugged before the pregnant person lies down to sleep, ensuring no sustained heat exposure occurs overnight.
If a blanket must be used while awake, it should be set to the lowest possible comfortable setting. Monitor for signs of overheating, such as sweating, flushing, or feeling uncomfortably warm, and turn the blanket off immediately if these occur. Additionally, the blanket should never be placed directly on the abdomen for prolonged periods, as this concentrates heat near the developing fetus.
For those who prefer to avoid heated blankets entirely, several safe alternatives can provide warmth without the thermal risk.
Safe Alternatives
- Layering the bed with multiple lightweight, non-electric blankets, such as wool or flannel, to trap heat effectively.
- Wearing warm sleepwear, including thermal socks, is a simple way to maintain comfort.
- Using a microwavable heat pack or a warm (not hot) water bottle for localized warmth, such as at the feet, while avoiding placement directly over the abdomen.