|  | Conditions Treatments | Medical Conditions

Physiological Differences of Premature Infants

A premature infant is an infant that is born earlier than 37 weeks gestation. Premature infants are born before their bodies have completely developed; thus, there are often significant physiological differences between these infants and full-term ones. Premature infants may exhibit low birth weight, lanugo, respiratory distress, poor muscle tone, immature genitals, and thin, translucent skin.

  1. Low Birth Weight

    • Premature infants are more likely, relative to full term infants, to have low birth weight, which is a weight less than 5 lbs., 8 oz. Approximately 70 percent of infants in the low birth weight category are born prematurely. The rest of low birth weight infants are full-term infants that undergo growth restriction in utero.

    Lanugo

    • Lanugo is soft, fine hair that may be found all over the body of a premature infant. It appears on the body at five months gestation, and is shed by seven or eight months gestation, unless the baby is prematurely born before this time. Lanugo that is present at birth is not a long-term issue: it generally disappears within a few weeks.

    Neonatal Respiratory Distress Syndrome

    • Respiratory distress is a very serious concern in the premature infant. The cause of the syndrome is a lack of surfactant, which keeps the air sacs within the lungs open. The lungs begin to produce surfactant when an infant is near term. The risk for neonatal respiratory distress syndrome increases as the age of the infant at birth decreases, and is highest when the infant is born before 28 weeks gestation.

    Poor Muscle Tone

    • At birth, the muscles of a premature infant display a lesser extent of development relative to a mature infant. This results in poor feeding, as the muscle surrounding the cardiac sphincter, which closes off the esophagus from the stomach during digestion, is not strong enough to fully close the junction. Thus, the premature infant is more prone to regurgitate food than a mature infant would be. Another consequence of poor muscle tone is low activity. At birth, the premature infant does not move as much as the mature infant would.

    Immature Genitals

    • If the premature infant is female, she is likely to have an enlarged clitoris. If the premature infant is male, he is likely to have a small scrotum lacking the usual ridges, as well as undescended testicles.

    Underdeveloped Skin

    • The integrity of the skin, an important protective organ, may be compromised in the premature infant.

      The skin of a premature infant is often underdeveloped, as evidenced by the translucent appearance. The outer epidermal layer of the skin may not be attached very well to the dermal layer underneath. This places the infant at risk for dehydration, infection and skin breakdown.

Medical Conditions - Related Articles