How hot is a newborn's fever?

This is an automatically translated article.

The article is professionally consulted by Master, Doctor Phan Thi Cam Van - Neonatologist - Pediatrics - Neonatology - Vinmec Danang International General Hospital
Newborn fever is a very common condition that most babies experience. However, not everyone knows exactly how hot a baby is to have a fever. The correct definition of fever and how to measure the baby's temperature is extremely important, helping parents to take care of their children properly.

1. Causes of fever in babies

Fever is a defense response of the body's immune system against various conditions and agents. This is a very common symptom in children, any age can have a fever, the younger it is, the easier it is to have a fever. Although fever is a good sign that the body is capable of anaphylaxis, it is also one of the top reasons why many parents worry and take their children to the doctor.
There are many different causes of fever in babies, the most common of which is bacterial infection. Infections caused by viruses and bacteria that often present with fever are:
Colds; Diarrhea ; Ear infections; Acute laryngitis ; Bronchiolitis; Inflammation of the respiratory tract; Enteritis; Urinary tract infection; Skin infections; TB infection
However, sometimes the newborn has an infection but does not have a fever, or the immunocompromised and severe TB do not have a fever. Besides, a number of other causes are also thought to cause fever in babies such as:
Sunburn, heat stroke; After receiving several vaccines; Prolonged and continuous use of antibiotics; Teethe. However, there are also studies that deny fever is related to teething; Wrap babies under 3 months of age in lots of clothes. This may increase the child's temperature slightly, but when the rectal temperature reaches 38.5oC, it is necessary to look closely to find other causes of fever. In general, in these cases, the fever will not last more than 2 days. Fever in young children is usually easy to reduce if the cause is found and treated properly.

2. How hot does a newborn baby have a fever?

Body temperature is controlled by the hypothalamus of the brain. Body temperature fluctuates within a relatively narrow range during the day due to maintenance of the hypothalamus. This organ regulates temperature by balancing heat production by the muscles and liver with heat loss through the skin and lungs. Fever occurs when the hypothalamus raises body temperature.
Normal body temperature of healthy children ranges from 36.8 - 37.3°C. The afternoon temperature is usually about 0.5 degrees higher than the morning temperature. Answering the question "How hot does a newborn baby have a fever?", doctors said that an infant has a fever when:
The temperature in the rectum (anus) is > 100.4oF (38°C); Oral temperature > 99.5oF (37.5°C); Axillary temperature > 99oF (37.2°C); Ear temperature > 100.4oF (38°C) In fact, measuring temperature rectally or in the ear is the most accurate, but in the armpit is the simplest, so it is widely used by many people.
Newborn high fever is when the body temperature is between 39 - 40°C, if it is above 40.5°C, it is a medical emergency for the child because it can easily lead to convulsions. However, in many children with a history of convulsions, the threshold for febrile convulsions may be lower, possibly even a fever < 38°C is at risk of convulsions.

4. How to take body temperature

If you see a child with symptoms such as waking up in the middle of the night, grimacing, tired, rosy cheeks, hot body, sweating, ... parents should use a thermometer to measure the child's body temperature immediately. It is preferable to use electronic thermometers to ensure safety and higher accuracy than mercury thermometers.
How to take baby's body temperature at armpits, mouth, anus, ears, forehead/temporaries based on age as follows:
Children under 3 months old: Body temperature can be taken under armpits for the convenience of babies birth, if > 37.2°C, rectal temperature should be used. After using a rectal thermometer, if the result is 38°C or higher, take your baby to the doctor immediately; Children from 3 - 5 months old: Can take temperature at armpit or ear; Children under 4 years old: The thermometer can be clamped under the armpit to determine the body temperature, when it is 38°C or more, it is considered a fever; Children over 4 years old: Oral body temperature will give high accuracy, children have a fever when the temperature is 37.8°C or higher; Older children: The thermometer can be clamped under the armpit.

5. Home treatment when the infant has a fever

Almost every child will have some fever at some point, so it's up to parents to know how to handle it. In addition to knowing how hot a newborn is, a fever, parents can also refer to some of the following guidelines:
Take off the baby's clothes and wipe with warm water in the armpit, groin, and head for about 5 - 15 minutes to open the pores and let the heat out, then put on light cotton clothes again; Give your baby plenty of water to drink to make up for the loss of water through perspiration and respiration. Breastfeeding children will still breastfeed on demand; Stop eating when the fever is high to prevent the baby from having a convulsion. When the fever is over, give the baby a light meal with easily digestible food; Watch for signs of fever to find the cause of the fever and heed warnings of serious illness; Re-measure the body temperature every 30 minutes, if the temperature has not dropped, you should give the baby fever-reducing medicine or insert medicine in the anus. In addition, loved ones SHOULD NOT do things that not only do not work to reduce fever, but also cause danger and increase the following undesirable effects:
Warm up; cold compress; Use alcohol or leaves to rub the skin, wipe the baby's body; Arbitrary use of antibiotics; Concomitant use of paracetamol and ibuprofen.

6. When is a fever worrisome?

Most cases of fever can be monitored and treated at home. However, it is important for parents to know when to take their child to the doctor or give them fever-reducing medicine. Parents need to contact medical staff for more specific instructions on the child's condition when:
High fever is difficult to lower, even after cooling off and taking antipyretics; Fever accompanied by other dangerous symptoms such as vomiting, wheezing, fatigue, startling panic, cold hands and feet, skin rash... High fever continuously for 2-3 days or fever recurs in more 1 week; Children > 3 months of age with a fever of 38oC for more than 3 days or showing signs of restlessness, refusing to breastfeed,... Children 3 - 36 months of age have a fever of 38.9oC or older children have a fever of 40oC; Children with underlying diseases: Cardiovascular, cancer, lupus, sickle cell,... Particularly for infants under 3 months of age, especially those still in the month, they must definitely go to the doctor and need to be hospitalized to find the cause. fever, even if the child appears to be fine.
The treatment of fever is controversial because the condition plays a role in fighting infection even though it can be uncomfortable for the child. Neonatal high fever is not a prerequisite for treatment, but rather other behaviors and symptoms associated with fever considered by healthcare professionals.

In short, a fever occurs when a child's body temperature is higher than normal. To prevent dangerous complications when a newborn has a fever, parents need to know how to measure their baby's temperature, know how hot a newborn is, and how to handle it appropriately. It is necessary to take the newborn with a high fever to the hospital if the baby has other abnormal signs. You should take your baby to a hospital with a pediatric specialty so that he can promptly handle them when he has neurological and cardiovascular complications when the fever is too high and does not go down, fever convulsions.
Pediatrics Department at Vinmec is one of the few pediatric multi-specialty hospitals, full of specialists in cardiology, neurology, dermatology, gastroenterology, nutrition, psychology... helping to treat comprehensive and effective for children.
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