Blood Pressure in an Infant

Blood pressure refers to the force of blood against your artery walls. Blood pressure is characterized by two numbers that represent your heartbeat, known as systolic pressure, and your heart muscle relaxing between beats, called diastolic pressure. The measurement is written out with your systolic pressure over the diastolic pressure, or the two numbers separated by a slash. An infant's blood pressure is measured in relationship to birth weight.

An infant's blood pressure is different when she's awake, crying and asleep.Photo Credit Jupiterimages/Polka Dot/Getty Images.

Normal Blood Pressure

The normal blood pressure in an infant varies by age and depends on whether the baby is sleeping, awake or crying. At birth, the approximate normal blood pressure of a healthy baby is 61 to 79 systolic over 30 to 54 diastolic. At 1 month of age, normal blood pressure is 75 to 95 over 37 to 55. By 6 months, a baby's blood pressure is 79 to 107 over 46 to 64 and at 12 months, 83 to 105 over 48 to 64.

SIDS

SIDS, known as sudden infant death syndrome, may be linked to low blood pressure and sleeping position in premature babies. In 2008, researchers from Australia's Monash University in Melbourne found that preterm babies have lower blood pressure while sleeping during the first six months, compared to full-term infants. Low blood pressure was also linked to preterm infants who slept face down. Premature babies represent about 20 percent of SIDS cases. The researchers report that falling blood pressure while asleep is linked to the deadly syndrome.

Taking Blood Pressure

A baby's blood pressure can be measured using a stethoscope and blood pressure cuff. The upper arm is typically the best place to do a blood pressure reading on an infant, unless the baby has intravenous lines or a catheter. Using the wrong cuff size, or the baby's level of comfort can affect the reading. A cuff that is too large can cause a small decrease in accuracy, a cuff that is too small, however, can cause an inaccurate reading that is significantly elevated.

Blood pressure disorders

Although infants may be treated for hypotension, low blood pressure, and hypertension, high blood pressure, researchers from Case Western Reserve University School of Medicine in Cleveland report that determining the normal blood pressure range is not a perfect science. Hypotension in infants can be caused by heart problems, an infection in the blood, or blood loss. Low-weight and premature babies are also at risk for having low blood pressure. Hypertension in pre-adolescent children is often a secondary condition caused by kidney disease or heart disease. The National Institutes of Health reports that several factors affect infant blood pressure, including hormones, heart and blood vessel health, and kidney health.

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