A baby’s fever can be a significant concern for parents, prompting a need to understand what constitutes a high temperature and how to respond. Recognizing fever signs and accurately measuring temperature are important. Understanding temperature thresholds for different methods helps parents make informed decisions about seeking medical guidance.
Understanding Fever Temperatures in Babies
A fever in babies is defined as a body temperature of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher. This threshold applies across various measurement sites, including the forehead (temporal artery), rectum, and ear. While feeling a baby’s forehead can suggest warmth, it is not a precise method for determining fever. Digital thermometers provide a more accurate reading.
Forehead (temporal artery) thermometers measure infrared heat waves from the blood vessel just beneath the skin on the forehead. They offer a quick, less intrusive way to check a baby’s temperature and can be used for all ages. For infants under three months, a forehead temperature of 100.4°F (38°C) or higher is considered an emergency. While useful for screening, they are less precise than rectal thermometers.
The rectal temperature is considered the most accurate method for determining core body temperature, particularly for infants under three months. It directly measures internal temperature for reliable readings.
Forehead temperatures can be influenced by external factors like sunlight, cold, sweat, or head coverings, leading to less accurate readings. Oral temperatures are not recommended for children under four. Ear (tympanic) temperatures are not reliable for babies younger than six months due to narrow ear canals. Armpit (axillary) temperatures are the least accurate but can be used for initial screening. A reading of 99°F (37.2°C) or higher requires a more precise measurement.
Accurately Taking Your Baby’s Temperature
When using a temporal (forehead) thermometer, follow the manufacturer’s instructions. Place the sensor on the center of the baby’s forehead and slowly slide it across towards the hairline near the top of the ear. Some newer models are “no-touch” and require aiming the thermometer from a short distance. Ensure the forehead is clean and free of sweat, and avoid taking a reading immediately after crying, bathing, or direct sunlight, as these can affect accuracy.
For a rectal temperature, use a digital rectal thermometer. Lubricate the tip with petroleum jelly. Place the baby on their belly across your lap or on their back with legs pulled to the chest. Gently insert the lubricated tip about 0.5 to 1 inch into the anus, pointing it towards the belly button.
Hold the thermometer in place until it beeps, then remove and read. Clean the thermometer with soap and water or rubbing alcohol after each use.
An armpit (axillary) temperature can serve as a preliminary check. Place the tip of a digital thermometer in the baby’s dry armpit, ensuring it touches only skin, not clothing. Hold the baby’s arm gently against their body to keep the thermometer in place until it beeps. If this reading indicates a fever, follow up with a more accurate method like a rectal or temporal temperature for confirmation.
When to Contact a Healthcare Professional
For babies younger than three months old, any temperature of 100.4 degrees Fahrenheit (38 degrees Celsius) or higher, taken rectally or on the forehead, warrants an immediate call to a healthcare professional or a visit to the emergency room. This is because their immune systems are still developing, and a fever can indicate a serious underlying infection.
For infants between three and six months old, a temperature of 100.4°F (38°C) or higher accompanied by signs of illness, or any temperature above 102.2°F (39°C), requires a doctor’s call. For babies aged six to twenty-four months, a fever above 100.4°F (38°C) lasting more than one day, or a temperature higher than 102.2°F (39°C), also requires medical consultation.
There are specific warning signs that indicate a need for urgent medical care with a fever at any age:
Extreme lethargy, unusual drowsiness, or difficulty waking the baby.
Difficulty breathing, such as fast or labored breathing, flaring nostrils, or skin pulling in between the ribs.
Persistent crying that cannot be consoled.
A stiff neck.
An unexplained rash (especially one that doesn’t fade when pressed).
Refusal to feed.
Signs of dehydration like fewer wet diapers.
Parents should also seek medical advice if the fever lasts more than three days or if their baby has a chronic health condition.