OBJECTIVES: I. Assess and compare the incidence and severity of cardiorespiratory events documented by home monitoring in infants at increased epidemiological risk for sudden infant death syndrome (SIDS).

II. Determine the antecedent medical, demographic, physiologic, and behavioral characteristics that predict the incidence of cardiorespiratory events documented by home monitoring.

PROTOCOL OUTLINE: This is a multicenter collaborative study. Patients are stratified into 4 groups: healthy term infants, apnea of infancy, subsequent siblings of SIDS victims, and preterm infants.

The caregivers are trained in the use of home monitor equipment and in the graded response to monitor alarms (observation, gentle stimulation, more vigorous stimulation, mouth to mouth breathing, and full cardiopulmonary resuscitation).

Caregivers undergo infant cardiopulmonary resuscitation (CPR) training (not required for caregivers of healthy term infants).

Demographic information is obtained on each infant. A 30 second recording of each infant's cry is performed at study entry and at 1 month corrected age, and at the polysomnogram. A urine sample is collected and frozen.

The CHIME monitor is used during sleep and whenever the infant is not being observed.

An overnight polysomnography is performed within 2 weeks of study entry. At 1, 2.5, 6, and 12 months corrected age, infants participate in a clinical evaluation. Neurodevelopmental status is assessed at 1, 4, and 12 months corrected age.

PROTOCOL ENTRY CRITERIA:

--Disease Characteristics-- Healthy term infants or infants at high epidemiologic risk for SIDS meeting one of the following criteria: Apnea of infancy Siblings of SIDS victim Preterm infants --Prior/Concurrent Therapy-- All study groups: No home treatment with supplemental oxygen, bronchodilators, diuretics, steroids, or respiratory stimulants other than methylxanthines Healthy term infants: No prior/concurrent medications or treatments except: Vitamins Eye prophylaxis Vaccines --Patient Characteristics-- All study groups: No concurrent pneumonia No history of congenital heart disease Current asymptomatic PDA or ASD, or small muscular VSD, not requiring treatment are allowed No ventriculoperitoneal shunt No home anticonvulsant therapy No congenital brain anomalies documented by head ultrasound, CT, or MRI No gastroesophageal reflux being treated by medication No midfacial hypoplasia or cleft palate No prior inborn error of metabolism (including MCAD or carnitine deficiency) No caregiver currently using illicit drugs No language barrier between researcher and caregiver Must have telephone in the home Healthy term infants: Gestational age at birth of 38-42 weeks Age no greater than 30 days postnatally for planned monitor start date Not admitted to a special care nursery Nursery discharge on/before date of maternal discharge or 48 hours of age, whichever is later No history of apnea or apparent life threatening event (ALTE) No history of SIDS in full or half siblings No history of SIDS in cousins, aunts, and uncles in the last 10 years 1 minute APGAR at least 4 5 minute APGAR at least 7 Apnea of infancy: Diagnosed ALTE (during sleep or awake) characterized by color change, muscle tone change, and apnea requiring intervention No specific etiology for the ALTE after a thorough diagnostic evaluation At least 12 hours of age and less than 6 months postnatal age when ALTE occurred Greater than 34 weeks gestation Weight greater than 1750 g Siblings of SIDS victim Half or full sibling of at least one previous SIDS victim Less than 1 month postnatal age at study entry Autopsy report confirmed SIDS in sibling Preterm infants Birth weight less than 1750 g Gestational age no greater than 34 weeks Postnatal age less than 120 days at time of hospital discharge