A newborn baby’s body temperature above 100.4°F (38°C) when measured rectally is considered a fever. While a fever in a newborn can be a cause for concern for parents, it is a symptom that requires immediate medical evaluation to determine the underlying cause. This article explores factors that can lead to a newborn presenting with an elevated temperature.
Maternal Health Factors
A mother’s health status during labor and delivery can directly influence a newborn’s temperature at birth. If a mother develops a fever during labor, often due to an infection or epidural side effects, this elevated body temperature can transfer to the baby. The infant’s temperature regulation system is still developing, making them susceptible to absorbing heat from the mother.
One significant maternal condition is chorioamnionitis, an infection of the amniotic fluid and the membranes surrounding the baby. This bacterial infection can cause fever in the mother and lead to the baby being born with an elevated temperature due to direct exposure to the infection. Another common bacterium, Group B Streptococcus (GBS), can be present in a pregnant mother’s birth canal. If untreated, GBS can transmit to the baby during delivery, potentially causing an early-onset infection that manifests as a fever at birth.
Infant-Specific Infections
Newborns can develop infections around the time of birth, leading to a fever. Early-onset sepsis is a serious bloodstream infection that occurs in newborns, typically within the first few days of life, and is a major cause of fever in this age group. This condition often results from bacteria acquired during passage through the birth canal or uterine environment. Common pathogens responsible for early-onset sepsis include Group B Streptococcus, Escherichia coli, and Listeria monocytogenes.
These bacteria can rapidly spread throughout a newborn’s immature system, triggering an inflammatory response. Less commonly, congenital infections, acquired in the womb, can also cause fever at birth. Viruses like cytomegalovirus (CMV), parasites such as Toxoplasma gondii, or bacterial infections like syphilis, though infrequent, can lead to systemic illness in the newborn, with fever as a presenting symptom.
Non-Infectious Reasons
Not all fevers in newborns are due to infection; non-infectious factors can also cause an elevated temperature. Newborns have an underdeveloped ability to regulate their body temperature, making them prone to overheating. If the birthing environment is excessively warm, or if the baby is overly bundled, their temperature can rise. This environmental overheating can mimic infection signs, necessitating medical evaluation to differentiate the cause.
In rare instances, an infant born to a mother who used certain substances during pregnancy may experience drug withdrawal. Symptoms can include irritability, tremors, and elevated body temperature. Additionally, uncommon neurological issues, such as brain injury or hemorrhage, can affect the baby’s hypothalamus. The hypothalamus regulates body temperature, and damage to this area can lead to a fever.
Medical Assessment and Initial Steps
When a baby is born with a fever, healthcare professionals initiate an immediate evaluation to identify the cause. The initial assessment includes a physical examination and continuous monitoring of vital signs. Due to the potential seriousness of fever in a newborn, especially given their underdeveloped immune system, diagnostic tests are typically performed without delay.
Tests often involve blood work, including a complete blood count to assess infection markers and blood cultures to identify bacterial presence. A urine test may also check for urinary tract infections. In many cases, a lumbar puncture (spinal tap) is performed to collect cerebrospinal fluid, which is then analyzed to rule out serious infections like meningitis, which can be life-threatening in newborns.
While awaiting diagnostic test results, which can take 24 to 48 hours, broad-spectrum antibiotics are typically administered. This proactive treatment addresses potential bacterial infections promptly and minimizes risks. Medical staff provide information to parents regarding the baby’s condition and the ongoing diagnostic and treatment plan.