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Babies who are born "too soon" or "too small" are at risk for many complications. Those who are born "too soon" are called premature; they are born before the 36th week of gestation (i.e., at least a month early). An infant (who may be full-term - 40 weeks or more) who weighs less than 5 1/2 pounds is "too small," or dysmature. The implications for disabilities are somewhat different for these two groups

In a premature infant, body systems or physical characteristics may not be fully developed, and the more premature the less developed. There is less muscle tone (the infant is more likely to lie in an extended (position than in a flexed position), the respiratory system (ability to breathe) is not fully developed, the brain may not be ready to control breathing yet, and an immature nervous system may inhibit the feeding process (sucking). The baby may also experience jaundice (a yellowing of tissue because the liver is not yet able to regulate the secretion of bilirubin) , hypoglycemia (not enough glucose in the blood), and hypothermia (an inability to maintain body temperature because there is not enough insulating fatty tissue). Advanced medical procedures are able to manage these factors in many premature infants, but careful monitoring (usually in a neonatal intensive care unit, or NICU) is necessary until the child's body systems mature enough to function independently.

In a dysmature infant, the chances of respiratory distress are less, but the baby may still experience hypothermia, hypocalcemia (not enough calcium in their blood), and hypoglycemia. The incidence of developmental disabilities is higher in low birth-weight babies. Dysmaturity is more likely in babies whose mothers had poor nutrition during pregnancy, or were chronically ill, and adolescent mothers are at particularly high risk for low birth-weight babies.

Current neonatal intensive care units try to duplicate womb conditions for premature and/or low birth- weight infants. The lighting may be reduced with blankets over the incubator or crib, or gauze over the infant's eyes. Noise is controlled (kept under 50 db). Infants may be ' swaddled" (wrapped, to maintain skin contact). Indirect and continuous contact with the child's natural mother may be maintained by placing a bandanna worn by the mother (and saturated with her unique odor) lightly over the infant's face or eyes. The baby's own states may be monitored so that treatment occurs at the most receptive times (usually the "alert" stage). (The "states" are: deep sleep, REM sleep, drowsiness, alertness, fussiness, crying.) Self-regulation on the part of the baby is the desired goal. ("Neurobehavioral stability" is the term used to describe this self-regulation.)

Caregivers are taught to watch for signs of distress or agitation in the infant (changes in skin color or breathing patterns; "visceral" signs such as drooling, limpness, hyperextension, arching, stiffening, flailing of arms or legs, startle reflex) Caregivers are also taught how to alleviate the stress or agitation, by speaking quietly, moving slowly, supporting the infant's shoulders, giving the infant's feet something to push against, and swaddling.

Among infants who have experienced respiratory distress and required ventilation, a number will develop an eye condition with the potential for severe visual impairment. Retinopathy of prematurity (formerly called retrolental fibroplasia) occurs primarily in premature infants born at 23-28 weeks gestation, or in those weighing less than 1000 grams (about 2 pounds 3 ounces), although it has also occurred in some full -term infants. The condition is related to retinal blood vessels, which are not fully developed in premature infants. Although oxygen was long believed to be the culprit in causing the disease, it is not a sole factor; the exact cause (and best treatment) of ROP has yet to be discovered (even after over 50 years of study). Current guidelines for perinatal care recommend that all infants born at less than 30 weeks of gestation, or who weigh less than 1300 grams at birth, should be checked for ROP before leaving the hospital, regardless of whether they were exposed to oxygen.

ROP has a wide range of impact. In as many as 90% of infants who develop the disease, it resolves itself with no treatment. In the infant whose ROP does not spontaneously resolve, cryotherapy may help prevent its progression, but hundreds of children still end up severely visually impaired (many of them blind). Whenever low birth-weight or prematurity are mentioned in medical records, the possibility of ROP should be investigated, to be sure it was either ruled out or identified. If ROP is listed as a visual diagnosis, a careful analysis of the eye report should reveal the extent of the disease (i.e., which stage). Since functional vision can range from useful to useless, a diagnosis of ROP should always be cause for referral to the VI teacher.

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