Oxygen saturation and breathing patterns in infancy. 1: Full term infants in the second month of life.

Overnight 12 hour tape recordings were made of arterial oxygen saturation (SaO2, pulse oximeter in the beat to beat mode) and abdominal wall breathing movement on 67 healthy, full term infants between the ages of 29 and 54 (median 39) days. The median baseline SaO2 during regular breathing was 99.8% (range 97.0-100%). Fifty four infants (81%) had shortlived episodes during which SaO2 fell to 80% or less (desaturation); the median rate was 0.9 desaturations/hour, and the median duration of each desaturation was 1.2 seconds. The 97th centile value for the duration of all episodes in which SaO2 fell to less than or equal to 80% was 4.0 seconds. The frequency of desaturations was significantly higher, and their duration significantly longer, when the breathing pattern was non-regular rather than regular. The percentage of apnoeic pauses (greater than or equal to 4 seconds in duration) followed by a desaturation was higher during non-regular than regular breathing; it was particularly high during periodic breathing. A knowledge of normal variability of baseline measurements of oxygenation and of the relationship between oxygenation and breathing patterns in infants is essential to the use of pulse oximetry in clinical practice.     

Arterial oxygen saturation in preterm infants at discharge from the hospital and six weeks later.

To obtain normal data on arterial oxygen saturation (SaO2) in preterm infants and to study early developmental changes in SaO2, we obtained overnight tape recordings of SaO2 and breathing movements in 160 preterm infants at their discharge from three special care baby units (mean gestational age at birth 33 weeks; at time of study, 37 weeks). One hundred ten infants (69%) underwent a second recording 6 weeks later. Median baseline SaO2 during regular breathing was 99.5% (range 88.7% to 100%) at discharge, and 100% (range 95.3% to 100%) at follow-up (p less than 0.001). The number of episodes of desaturation, defined as a fall in SaO2 to less than or equal to 80% for at least 4 seconds, corrected to the mean duration of recording (12.2 hours), decreased from a median of 3 (0 to 355) to 0 (0 to 17) (p less than 0.001). The median duration of each episode of desaturation remained unchanged (5.2 (4.0 to 22.7) vs 5.5 (4.2 to 24.0) seconds). At discharge, a small minority of infants had a clinically unrecognized low baseline SaO2 (lowest, 88.7%; 5th percentile, 95.7%) or a high number of desaturation episodes (the highest was six times the 95th percentile value). At follow-up, all outlying values had normalized. Follow-up recordings made between 42 and 47 weeks of gestational age (n = 53) were compared with similar recordings from 67 term infants at the same gestational age. The preterm infants had a significantly higher baseline SaO2 and no more desaturation than the infants born at term. Knowledge of normal ranges of oxygenation and their changes with age may be of value in identifying clinically undetected hypoxemia in preterm infants at discharge from the hospital. The potential influence of such hypoxemia on clinical outcome remains to be determined.     

Patterns of oxygenation during periodic breathing in preterm infants

The characteristics of the arterial oxygen saturation (SaO2) signal during episodes of hypoxaemia (SaO2 less than or equal to 80% for greater than or equal to 4 s) associated with periodic and non-periodic apnoeic pauses were studied in 16 preterm infants with cyanotic episodes (patients). and 15 asymptomatic preterm infants (controls), matched on birthweight and gestational age. The patients showed a significantly higher percentage of apnoeic pauses followed by a hypoxaemic episode (25 vs. 6%, P less than 0.01), and a two-fold increase in the slope of the desaturation curve (8.4 vs. 4.3% per s, P less than 0.005) in periodic compared with non-periodic breathing. All other characteristic of oxygenation (baseline SaO2 before episodes of hypoxaemia, delay between onset of apnoeic pause and onset of desaturation, lowest SaO2 during episodes of hypoxaemia) were similar for periodic and non-periodic breathing patterns. Similar, but not significant, differences between isolated and periodic apnoeic pauses were also present in the controls. An analysis of episodes of bradycardia (less than or equal to 100 beats per minute (bpm] showed that out of 121 episodes in the patients 118 were accompanied by a fall in SaO2 to less than or equal to 80%, and in the remaining three SaO2 fell to 82%, 85% and 86%, respectively. Thus all episodes of bradycardia (less than or equal to 100 bpm) were associated with a fall in SaO2 detected by beat-to-beat pulse oximetry. Examination of hypoxaemic episodes and their relationship with bradycardia and with apnoeic pauses, periodic and non-periodic, may help the further understanding of the control of arterial oxygenation in preterm infants with cyanotic episodes.     

Oxygen saturation and breathing patterns in preterm infants with cyanotic episodes

The pathophysiology of cyanotic/apnoeic episodes in preterm infants was investigated using overnight tape recordings of beat-to-beat arterial oxygen saturation (SaO2), plethysmographic waveforms from the oximeter, breathing movements and nasal airflow. Recordings were made in 16 preterm infants with recurrent cyanotic episodes of unknown cause that had received stimulation or resuscitation, and 15 preterm controls, matched for birth weight, post-conceptional and postnatal age. The recordings were analysed for baseline SaO2, the number of hypoxaemic episodes (SaO2 < or = 80% for > or = 4 s) and the breathing patterns associated with each episode. There was a significant difference in the total number of hypoxaemic episodes between patients and controls (520 versus 100; p < 0.01), but no difference was found for mean baseline SaO2 (98.6 versus 99.0%; p > 0.05). The mean duration of each hypoxaemic episode in the patients was 9.5 s compared with 5.8 s in the controls (p < 0.01). Although most hypoxaemic episodes (62 and 76%) were associated with pauses in breathing movements, a proportion (8 and 18%, respectively) occurred despite continuous airflow and breathing movements in both patients (6 of 16) and preterm controls (2 of 15). The rate of decrease in SaO2 was significantly more rapid during these latter hypoxaemic episodes than during episodes associated with isolated apnoeic pauses (8.5 versus 3.2% per second, p = 0.02). Preterm infants with cyanotic episodes have increased numbers of clinically unapparent hypoxaemic episodes, some of which have continued ventilation and rapid desaturation. The pathogenesis of these episodes warrants further investigation.     

High density lipoprotein concentrations in newborn infants.

The lipoprotein pattern was analyzed by agarose gel electrophoresis in 19 new born infants of varying gestational age. The HDL concentration was determined by rocket immunoelectrophoresis in another 41 newborn infants. Infants with a gestational age of less than 33 weeks had very low HDL concentrations compared to preterm infants with a gestational age of less than or equal to 33 weeks and term ihfants. In the first 5-10 days after birth the HDL concentration increased markedly in preterm infants (gestational age less than 37 weeks) whereas it remained unchanged in term infants.     

Hypoxaemia in infants with respiratory tract infections

Nineteen infants who were graduates from special care baby units underwent two overnight tape recordings of oxygen saturation (SaO2) and breathing movements; one during an upper (n = 12) or lower (n = 7) respiratory tract infection and the other when free of infection. Baseline SaO2 was lower during infection (median 99.6 vs 100%, p less than 0.01), with four patients having values (84.3-95.5%) below the normal lower limit for full-term infants (97%). The median number of apnoeic pauses was also lower during respiratory tract infection (4.7 vs 15.7/h, p less than 0.02). The median number of episodic desaturations (SaO2 less than or equal to 80%) did not change significantly (1.3 vs 1.9/h, p greater than 0.05), with the exception of one patient who had extremely increased values during infection for both apnoeic pauses (63/h) and desaturations (112/h). No infant, however, was considered clinically hypoxaemic. Clinically unsuspected hypoxaemia may thus occur during respiratory tract infection in a proportion of infants graduating from special care baby units. Such hypoxaemia may have potentially deleterious effects.     

The postnatal hypotransferrinemia of early preterm newborn infants.

Preterm newborns were found to be markedly hypotransferrinemic when compared with normal term infants. At birth the concentration of transferrin in sera from preterm infants of gestational age equal to or less than 32 weeks is 45% of that found in normal term infant sera. The preterm infant transferrin levels slowly rise so that 7-8 weeks after birth they are 78% of the level found in the sera of normal term infants. We also found that the serum transferrin concentrations at birth correlate with gestational age. Therefore, the transferrin levels postnatally in early preterm infants reflect postconceptional rather than postnatal age.     

Gestational evolution of small intestine motility in preterm and term infants

Continuous perfusion manometry was performed in 31 preterm and term infants to assess the influence of gestational age on small intestinal motility. Gestational ages ranged from 27 to 42 weeks. All 8 term infants had interdigestive cycles that included all three phases. Only 4 of 23 preterm infants had complete interdigestive cycles. The remaining 19 preterm infants had only periods of motor quiescence and nonpropagating contractions. In term infants the interdigestive cycle was significantly shorter and the amplitude of phase 3 activity was significantly greater (p less than 0.01); velocity and duration of phase 3 activity were similar in both groups of infants. Rhythmic nonpropagating activity, or clusters, made up more than 60% of the phase 2 activity in both term and preterm infants. Although clusters did not propagate across three or more leads, approximately 25% of cluster activity was propagated across two leads. The duration of total cluster activity was similar for all gestational ages, but the frequency of clusters decreased and the mean duration of individual clusters increased with gestational age (both p less than 0.01). The amplitude of individual pressure peaks in clusters and phase 3 increased significantly with gestational age (p less than 0.03 and p less than 0.01, respectively). The motility index also increased with gestational age (p less than 0.02). We conclude that small intestinal motility is more immature in preterm infants than in term infants. Furthermore, cluster activity, which increases in duration and amplitude with gestational age, may be an immature form of phase 3 activity. These data and techniques will provide neonatologists with a direct way of tracking preterm intestinal motor function to provide more appropriate enteral nutrition.     

Neurologic examination of preterm infants at term age: comparison with term infants

OBJECTIVES: The aim was to establish the range of neurologic findings in preterm infants reaching term age, their relation to gestational age at birth, and the possible differences with healthy term newborns tested during the first days of life. STUDY DESIGN: The Dubowitz neonatal neurologic examination was performed at term age in 157 low-risk preterm infants born between 25 and 34 weeks' gestation who had cranial ultrasonograms that were normal or showed minor abnormalities. Infants were subdivided in 3 groups according to their gestational age at birth. RESULTS: Within the preterm cohort, the range of scores for the 3 gestational age subgroups was different from each other for 21 of the 34 items, although the median scores were different only in 10 of the 34 items. The range of scores and their median in preterm infants however was wider than that found in term infants. Preterm infants examined at term were also more hyperexcitable and tended to have less flexor tone in the limbs and less extensor tone in the neck in the sitting posture. CONCLUSIONS: The distribution of scores provides useful guidelines when a preterm infant is examined at term.     

Placental transfer and decay of varicella-zoster virus antibodies in preterm infants

OBJECTIVES: To compare the placental transfer of maternal varicella-zoster (VZV) antibodies to preterm and term infants and to investigate antibody decay during the first 6 months of life in the preterm infants.Study design: Maternal and umbilical cord blood samples were taken from 113 healthy mother-newborn pairs: 64 term (gestational age > or =37 weeks) and 49 preterm (gestational age < or =35 weeks). Premature infants were further tested at 1, 2, and 6 months. Anti-VZV antibody to membrane antigen was measured with the immunofluorescent technique. RESULTS: Preterm infants of gestational age < or =28 weeks had positive cord antibody and a geometric mean titer significantly lower than those in preterm infants of gestational age 29 to 35 weeks and term infants (25% vs 95% and 95%, respectively, P <.001 for each, and 2.5 +/- 2.2 vs 10.5 +/- 2.4 and 12.6 +/- 2.4, respectively, P <.001 for each). There was no difference between the preterm 29 to 35 weeks of gestation and term groups. Fetal-maternal ratios for both preterm groups were <1 and were significantly less than the fetal-maternal ratio in the term infants. The transfer of maternal antibodies to term infants was significantly greater than to the 29- to 35-week preterm infants (P =.01). At 2 months of age, 25% of 29- to 35-week preterm infants and no preterm infant < or =28 weeks had a positive titer. At 6 months of age, all preterm infants were seronegative, and the geometric mean titer in both groups declined to undetectable levels. CONCLUSION: Transplacental transfer of maternal VZV antibodies is diminished in preterm infants. VZV antibody levels are significantly lower in preterm infants born at < or =28 weeks' gestational age compared with those in preterm infants 29 to 35 weeks' gestational age and term infants. Anti-VZV titers decrease to undetectable levels in preterm infants by 6 months of age or earlier; thus these infants appear to be susceptible to chickenpox before the scheduled 12-month vaccination.     

Magnetic resonance imaging of the brain in a cohort of extremely preterm infants.

To define magnetic resonance imaging (MRI) appearances of the brain in extremely preterm infants between birth and term, a sequential cohort of infants born at a gestational age <30 weeks was studied with a dedicated neonatal magnetic resonance scanner. Images of infants (n = 41) with a median gestational age of 27 weeks (range 23 to 29 weeks) were initially obtained at a median age of 2 days (range 1 to 20 days) and then repeatedly studied; 29 (71%) infants had MRI at a median gestational age of 43 weeks (range 38 to 52 weeks) (term MRI). On the initial MRI scan 28 of 41 infants had abnormalities: either intraventricular hemorrhage, germinal layer hemorrhage, ventricular dilatation, or diffuse and excessive high signal intensity in the white matter on T(2)-weighted images. When magnetic resonance images for preterm infants at term gestation were compared with those of infants in the control group born at term, 22 of 29 infants had dilatation of the lateral ventricles, 24 of 29 had squaring of the anterior or posterior horns of the lateral ventricles, 11 of 29 had a widened interhemispheric fissure or extracerebral space, and 22 of 29 had diffuse and excessive high signal intensity in the white matter. There were no cases of cystic periventricular leukomalacia. We conclude that MRI abnormalities are commonly seen in the brain of preterm infants on whom images are obtained within 48 hours of birth and that further abnormalities develop between birth and term. A characteristic appearance of diffuse and excessive high signal intensity in the white matter on T(2)-weighted images is associated with the development of cerebral atrophy and may be a sign of white matter disease. These MRI appearances may help account for the high incidence of neurodevelopmental impairment in extremely preterm infants.     

Developmental maturation of gastro-oesophageal reflux in preterm infants

The frequency and duration of gastro-oesophageal reflux were examined in 40 preterm infants and compared with a previously published healthy cohort of 74 term infants. Selection required that the infants were born between 24 and 32 weeks' gestation, had a normal head ultrasound and were studied at term post-menstrual age. Multi-channel pen recordings of sleep state, movement, breathing and acid reflux were made. In term and preterm infants the frequency and duration of reflux were greatest in active sleep, rare in quiet sleep and significantly less in preterm than term infants in wakefulness and active sleep ( p <0.05). The fewer and shorter episodes in preterm infants could not be explained by sleep state, movement, gestational or postnatal age, days intubated, days on oxygen or the lowest pH of reflux episodes.     

Oxygen saturation during the first 24 hours of life

AIM: To determine normative data for arterial oxygen saturation, measured by pulse oximetry (SpO2), in healthy full term infants throughout their first 24 hours of life. METHODS: Long term recordings of SpO2, pulse waveform, and breathing movements were made on 90 infants. Recordings were analysed for baseline SpO(2), episodes of desaturation (SpO2 /= four seconds, and periodic apnoea (>/= three apnoeic pauses, each separated by /= 20 seconds) were identified in six recordings. Four desaturations fell to 相似文献   

Neonatal opiate abstinence syndrome in term and preterm infants

Data on 178 term and 34 preterm infants born to methadone-maintained mothers were analyzed to assess the effects of neonatal opiate abstinence in infants of varying gestational ages. More mothers in the term group (79%) than in the preterm group (53%) had abused other drugs during pregnancy (p less than 0.001). Mean (+/- SD) gestational age was 39.5 weeks +/- 1.4 for term infants and 34.3 weeks +/- 2.6 for preterm infants. On the basis of a semiobjective symptom scoring scale, term infants had more severe abstinence symptoms and more prominent central nervous system manifestations than preterm infants. The severity of abstinence symptoms correlated with maternal methadone dosage in both term and preterm infants. Maternal multiple drug abuse (e.g., heroin, cocaine) did not influence severity of abstinence symptoms in either group. More term infants (145/178) than preterm infants (20/34) required treatment for these symptoms (p less than 0.005). In 13 of 178 term infants, compared with 1 of 34 preterm infants, abstinence-related seizures developed. Peak severity occurred 1 to 2 days earlier in term than in preterm infants. A less severe abstinence syndrome in preterm infants may be due to (1) developmental immaturity of either dendritic ramifications, specific opiate receptors, or neurotransmitter function, or (2) reduced total drug exposure during the intrauterine period.     

Home oxygen therapy after preterm birth in Western Australia

OBJECTIVES: To review our management of infants discharged home receiving supplemental oxygen. Stable preterm infants receive low flow O(2) by nasal cannulae aiming for SaO(2) of > or = 95%. Oxygen-dependent infants must pass an air test (ability to maintain SaO(2) > 80% during 4 h disconnection from oxygen) before discharge home with supplemental oxygen. A sleep study is performed before nocturnal O(2) is ceased. METHODS: Infants less than 33 weeks gestational age (GA) who were admitted January 1999-June 2001 and discharged home with supplemental oxygen were identified through the databases and medical records of the King Edward Memorial/Princess Margaret Hospitals. The data collected were compared with an audit performed a decade earlier. RESULTS: Ninety-three infants were discharged home with supplemental oxygen between 1999 and 2001 (10% neonatal intensive care unit admissions less than 33 weeks GA; median GA 26 weeks (interquartile range 25-28). All infants had an air test before discharge: 63% failed the first air test and 30% at least two air tests. The median delay between the first air test and discharge was 2 weeks. The median postmenstrual age at discharge was 40 weeks gestation (interquartile range 38-41). Ninety infants had a sleep study before nocturnal oxygen was ceased and nine failed the first sleep study. Hospital readmission rate was 60%. More preterm infants (less than 33 weeks) were discharged with supplemental oxygen in 1999-2001 (10%, n = 96 in 1999-2001) than in 1987-1992 (2.5%, n = 53) and this was associated with an earlier discharge (40 vs 44 weeks postmenstrual age), lower oxygen requirements at discharge (60 vs 125 mL/min), earlier discontinuation of daytime and nocturnal oxygen (1 vs 4 months postmenstrual age and 2.5 vs 6 months postmenstrual age) and no increase in readmission rate (64% vs 60%). The incidence of bronchopulmonary dysplasia for these infants has remained stable at 20%. CONCLUSION: Our home oxygen programme, based on an air test predischarge and a sleep study prediscontinuation of nocturnal oxygen, facilitates early discharge home. Our data suggest that over the last decade, bronchopulmonary dysplasia is associated with less impairment in lung function. Further evidence from randomized clinical trials is required to determine optimal target range for oxygen saturation in preterm infants.     

Behavioural response to pain in healthy neonates.

A bedside technique for evaluating the behavioural response of healthy neonates to pain was assessed. Thirty six term infants (median gestational age 40 weeks; median postnatal age 4 days) and 31 preterm infants (median gestational age 34 weeks; median postnatal age 4 days) were assessed at the cotside for their response to heel preparation and heel lance for routine blood sampling. The facial actions of brow bulge, eye squeeze, nasolabial furrow, and open mouth were noted, and also the presence or absence of crying. Thirty five (97%) term and 26 (84%) preterm infants showed an increase in the number of behaviours in response to heel lance. Brow bulge and nasolabial furrow were seen most often, and occurred more often than crying in the two groups. There was good interobserver agreement (94%). The consistency of response and the high degree of interobserver agreement makes this method of behavioural assessment of acute pain of use in healthy neonates.     

Intestinal permeability in relation to birth weight and gestational and postnatal age

OBJECTIVE: To determine the relation between intestinal permeability and birth weight, gestational age, postnatal age, and perinatal risk factors in neonates. STUDY DESIGN: Intestinal permeability was measured by the sugar absorption test within two days of birth and three to six days later in preterm and healthy term infants. In the sugar absorption test, the urinary lactulose/mannitol ratio is measured after oral ingestion of a solution (375 mosm) of lactulose and mannitol. RESULTS: A first sugar absorption test was performed in 116 preterm (26-36 weeks gestation) and 16 term infants. A second test was performed in 102 preterm and nine term infants. In the preterm infants, the lactulose/mannitol ratio was not related to gestational age (r = -0.09, p = 0.32) or birth weight (r = 0.07, p = 0.43). The median lactulose/mannitol ratio was higher if measured less than two days after birth than when measured three to six days later (0.427 and 0.182 respectively, p<0.001). The lactulose/mannitol ratio was higher in preterm infants than term infants if measured within the first 2 days of life (0.404 and 0.170 respectively, p < 0.001), but not different three to six days later (0.182 and 0.123 respectively, p = 0.08). In multiple regression analysis of perinatal risk factors, only umbilical arterial pH correlated with the lactulose/mannitol ratio in preterm infants less than 2 days of age (T = -1.98, p = 0.05). CONCLUSIONS: In preterm infants (26-36 weeks gestation), intestinal permeability is not related to gestational age or birth weight but is higher during the first 2 days of life than three to six days later. It is higher in preterm infants than in healthy term infants only if measured within two days of birth. This suggests rapid postnatal adaptation of the small intestine in preterm infants.     

Effects of bottle feeding and two different methods of gavage feeding on oxygenation and breathing patterns in preterm infants

Objective To determine the effect of bottle feeding, as compared to two methods of gavage feeding, on apnoea, bradycardia and oxygen desaturation frequency. Patients : Thirty preterm infants breathing room air; gestational age 28.6 ± 2.1 weeks at birth and 34 ± 1.4 weeks at study (mean ± SD). Methods : Nine-hour recordings of pulse oximeter saturation (SpO₂), pulse waveforms, electrocardiogram, breathing movements and nasal airflow. Administration of 21 ± 1.5 ml/kg of milk/feed in 3-h intervals using three different feeding techniques in random order: bottle feeding, bolus gavage feeding, and slow gavage feeding (1 h). Analysis of recordings for apnoeas (≥4 s, bradycardias (heart rate < 2/3 of baseline), and episodic desaturation (SpO₂≤ 80%). Results : There were three times more desaturations with bottle feeding than with bolus gavage feeding ( p < 0.001), but no further reduction with slow gavage feeding. With all three feeding techniques, there were significantly more desaturations in the hour when the feeds were given than during the following 2 h. The deleterious effects of bottle feeding were most evident during the hour of feeding, but desaturation frequency remained significantly higher than with gavage feeding during the following 2h. There was no significant effect of feeding technique on the frequency of apnoea or bradycardia. Conclusions : Preterm infants who are normally oxygenated in room air may have significant desaturation during bottle feeding. Such desaturation can be effectively reduced by gavage feeding. Slow gavage feeding offers no advantage over bolus gavage feeding with respect to the avoidance of hypoxaemia.     

Effect of postnatal age and clinical status of newborn infants on bilirubin-binding capacity

Serial determinations of bilirubin-binding capacity were performed in 61 newborn infants during the first 10 days of life. 27 infants were classified as term (gestational age greater than or equal to 36 weeks) and 34 as preterm (gestational age less than or equal to 33 weeks); 34 were classified as 'sick' and 27 as 'well'. Bilirubin-binding capacity was measured by Sephadex gel filtration. In relation to postnatal age, total bilirubin-binding capacity (TBBC) remained stable in well term and preterm infants, decreased slightly in sick preterm infants, and decreased significantly in sick term infants. TBBC, serum albumin, and molr binding ratio (B/A) were significantly higher in well than in sick infants in both term and preterm groups; there were no significant differences between sick term and sick preterm infants. Clinical recovery in 16 infants was associated with a significant rise in TBBC and in B/A. The data suggest that in healthy infants, the serum bilirubin-binding capacity remains relatively unchanged during the first 10 days of life. Clinically ill infants show wide patient-to-patient variability in TBBC. Because of the tendency of TBBC to decrease with postnatal age in sick infants, repeated determinations of TBBC may be indicated for the management of sick jaudiced newborns.     

A developmental study on types and frequency distribution of short apneas (3 to 15 seconds) in term and preterm infants

We measured the frequency distribution and the ventilatory correlates of the various types of apneas 3 to 15 s long during sleep in eight term infants (birth weight 3.65 +/- 0.16 kg; gestational age 39.5 +/- 0.3 wk) and eight preterm infants (birth weight 2.07 +/- 0.18 kg; gestational age 34.3 +/- 0.4 wk). Each infant was studied on five to seven occasions from birth to 56 wk of postconceptual age using a modified flow-through system. Sixty-six paired epochs of quiet sleep (1163 min) and rapid eye movement sleep (829 min) were analyzed in term infants and 85 paired epochs of quiet sleep (1553 min) and rapid eye movement sleep (1328 min) in preterm infants. Of the 783 apneas recorded in term infants 82% were central, 1.5% obstructive, 0.5% mixed, and 16% were of the breath-holding type; the corresponding figures for the 4086 apneas recorded in preterm infants were 93, 0.5, 1.0, and 5.5%. This distribution was similar in the two sleep states but term infants had a higher percentage of breath-holding apneas than preterm infants (p less than 0.01). In preterm infants the rate of central apneas decreased with postnatal age (p less than 0.01); in term infants the rate did not change significantly. The duration of apneas showed a modal distribution for central apneas at about 8 s for both groups during the 1st month of life (p less than 0.05). The findings suggest: 1) apneas in the newborn and early infancy are primarily central and are more frequent in preterm than in term infants.(ABSTRACT TRUNCATED AT 250 WORDS)