Increased inspiratory effort in infants with a history of apparent life-threatening event

The objective of this study was to compare the results of polysomnography between infants with a history of apparent life-threatening event (ALTE) and controls. In this case-control study, 40 full-term ALTE infants, aged 2-36 wk at the time of the event, were compared with 40 age- and sex-matched randomly selected controls. SaO2, tcpO2, tcpCO2, heart rate (HR), vector of rib cage and abdominal respiratory movements (phase angle, as an index of inspiratory effort) were recorded during natural nocturnal active and quiet sleep (AS, QS). SaO2, tcpO2, tcpCO2 were similar in ALTE and controls in both sleep states. Phase angle was increased in ALTE infants in both AS (59+/-46 vs 26+/-17 degrees) and QS (53+/-46 vs 18+/-14, p < 0.001). Eleven ALTE infants (27.5%) experienced SaO2 < 90%, with a mean decrease in SaO2 to 86+/-1.6% (mean +/- SD), compared with 10% for controls (p=0.003). In eight ALTE infants, SaO2 values <90% were linked to thoracoabdominal asynchrony. SaO2 < 90% in conjunction with HR <100 bpm were detected in three ALTE infants and one control. Periodic breathing was observed in 45% of ALTE infants and 40% of controls. CONCLUSION: The mean values of oxygen saturation, tcpO2 and carbon dioxide levels in ALTE infants are comparable with those of healthy controls but the ALTE infants exhibit more hypoxaemic episodes and increased inspiratory effort during sleep.     

Breathing patterns, oxygen and carbon dioxide levels in sleeping healthy infants during the first nine months after birth

Data on arterial oxygen saturation (SaO2), transcutaneous PO2, pCO2 (tcpO2, tcpCO2) and breathing patterns in sleeping healthy term infants were obtained during the first 9 mo after birth. Forty-four healthy infants, mean GA at birth 40 +/- 1.0 wk, mean BW 3520 +/- 562 g were examined between 2 wk and 9 mo postnatally in a cross-sectional study. SaO2, tcpO2, tcpCO2, heart rate (HR), rib cage and abdominal respiratory movements were recorded during natural nocturnal sleep, stratified for sleep states (active sleep (AS), indeterminate sleep (IS), quiet sleep (QS)). The data on AS and IS were pooled as in previous studies. The variables were analysed with respect to age. SaO2 in AS + IS and QS was 96.1 +/- 1.3%, 96.6 +/- 1.4%, respectively. TcpO2 in AS + IS was 10.6 +/- 1.1 kPa and 10.7 +/- 1.3 kPa in QS, while tcpCO2 in AS + IS was 5.4 +/- 0.3 kPa and 5.4 +/- 0.4 kPa in QS. Neither SaO2 nor tcpO2 was influenced by age. TcpCO2 decreased significantly postnatally. Five infants (11.3%) experienced episodes of hypoxaemia with a mean decrease in SaO2 to 86 +/- 1.5%. In four infants these hypoxaemic episodes were linked to upper airway obstructions. Episodes of SaO2 < 90% in conjunction with a decrease in HR to < 100 bpm were detected in one infant only. Periodic breathing (PB) was observed in 38.6% of infants. Conclusion: Oxygenation and carbon dioxide levels in sleeping healthy term infants were comparable to those reported in older children. Hypoxaemic episodes, if present, are associated with upper airway obstruction. PB, often assumed to be a pathological feature, is a normal breathing pattern in this age group.     

正常足月新生儿振幅整合脑电图特点的多中心研究

目的探讨正常足月新生儿生后3 d内振幅整合脑电图（aEEG）的特点,为新生儿临床脑功能监测提供依据。方法选择各参研医院母婴同室或新生儿室的正常足月新生儿为研究对象,依据胎龄分为37周～、38周～、39周～、40周～和41～42周胎龄组。采用首台国产aEEG仪记录正常足月新生儿生后1、2和3日龄的aEEG,每次记录3 h。采用半对数公式计算电压,分析正常足月新生儿aEEG背景波、电压、睡眠-觉醒周期及其影响因素。结果2008年5月至2009年5月纳入116名正常足月新生儿。①正常足月新生儿aEEG背景波呈现连续性波形。905％（105/116名）在生后1日龄出现睡眠-觉醒周期,所有正常足月新生儿在生后2日龄均出现睡眠-觉醒周期;②1个睡眠-觉醒周期的平均持续（699±187）min,其中宽带平均为（220±57）min,窄带平均为（479±171）min;③正常足月新生儿生后1、2和3日龄aEEG背景波最低电压分别为（128±34）、（121±20）和（125±26）μV,最高电压分别为（375±110）、（384±94）和（386±96）μV;④日龄、性别、分娩方式及母亲妊娠并发症对正常足月新生儿aEEG的宽带、窄带电压和时程均无显著影响,37周～胎龄组生后1～3日龄aEEG窄带电压上界较38～42周各胎龄组显著增高（P分别为0014,0001和0000）。结论正常足月新生儿aEEG背景波为连续波形,存在明显的睡眠-觉醒周期;最低电压均＞5 μV,最高电压均＞10 μV。37周～胎龄组的正常足月新生儿生后1～3日龄aEEG窄带电压上界较38～42周各胎龄组正常足月新生儿显著增高。正常足月新生儿的aEEG表现不受日龄、性别、分娩方式及母亲妊娠并发症的影响。     

Sleep state, hypoxia and periodic breathing in the neonate

The influence of sleep state on hypoxia-induced periodic breathing was evaluated in full-term babies studied during the first week of life. Following exposure to 15% O2, periodic breathing occurred in 7 of 42 babies during quiet sleep, and 5 of 20 during active sleep (p less than 0.05). The median levels of transcutaneous pO2 at which periodic breathing occurred during hypoxia, and was abolished on reoxygenation were similar in each sleep state. The median duration of periodic apnoea was significantly greater in quiet than active sleep. In 7 babies the occurrence of periodic breathing during hypoxia was accompanied by a change in sleep state. This was probably coincidental in 3 cases, but in the other 4 babies hypoxia may have induced both the change in state and breathing pattern.     

Relationship between functional residual capacity and oxygen desaturation during short central apneic events during sleep in "late preterm" infants

Apneic episodes are frequent in the preterm neonate and particularly in active sleep (AS), when functional residual capacity (FRC) can be decreased. Furthermore, FRC may be inversely correlated with the speed of blood-O(2)-desaturation. We evaluated the potential involvement of FRC in the mechanisms responsible for blood-O(2)-desaturation during short central apneic events (>3 s) in "late-preterm" infants and analyzed the specific influence of sleep state. Apneic events were scored in 29 neonates (postmenstrual age: 36.1 +/- 1.2 wk) during AS and quiet sleep (QS). FRC was measured during well-established periods of regular breathing. Apneas with blood-O(2)-desaturation (drop in SpO(2) >5% from the baseline, lowest SpO(2) during apnea: 91.4 +/- 1.8%) were more frequent in AS than in QS, whereas no difference was seen for apneas without desaturation. The magnitude of the FRC did not depend on the sleep state. In AS only, there was a negative relationship between FRC and the proportion of apneas with desaturation. Even in late preterm infants who do not experience long-lasting apnea, blood-O(2)-desaturation during short apneic events is related (in AS but not QS) to a low baseline FRC. Sleep stage differences argue for a major role of AS-related mechanisms in the occurrence of these apneas.     

Oxygen desaturation during sleep in infants and young children with congenital heart disease.

Oxygen saturation (SaO2) during sleep and pulmonary functions were evaluated in 19 infants with congenital heart disease, aged 6 +/- 4 months, and in 11 normal infants, aged 8 +/- 5 months, to determine whether infants with congenital heart disease have more frequent oxygen desaturation during sleep and, if so, its relationship to underlying pulmonary function. Infants with congenital heart disease were classified as acyanotic (n = 11) or cyanotic (n = 8) on the basis of their aortic SaO2 at the time of cardiac catheterization (greater or less than 90% SaO2). Pulmonary function tests included respiratory rate, functional residual capacity, total respiratory system compliance, and maximal flows at functional residual capacity. Significant differences were found in the values for the lowest SaO2 of each 5-minute epoch (SaO2L) averaged during the entire sleep time (normal 94% +/- 2%, acyanotic 90% +/- 3%, and cyanotic 74% +/- 4%; p less than 0.01). The three groups also differed significantly in frequency distributions of percentage of total sleep time with SaO2L less than 90% (SaO2%T) (normal 10% +/- 17%, acyanotic 36% +/- 34%, and cyanotic 97% +/- 4%; p less than 0.05). Compared with the control group, the acyanotic group had a higher respiratory rate (66 +/- 19 breaths/min vs 35 +/- 6 breaths/min; p less than 0.01), a lower tidal volume (65% +/- 29% predicted vs 105% +/- 18% predicted; p less than 0.01), and a lower total respiratory compliance (59% +/- 18% predicted vs 106% +/- 30% predicted; p less than 0.01). A negative correlation existed between SaO2%T and aortic SaO2 (R2 = 0.64; p less than 0.01). We conclude that oxygen desaturation occurs during sleep in infants with congenital heart disease; the presence of desaturation appears to be related to the initial degree of hypoxemia and the presence of abnormal pulmonary function.     

Sleep State, Hypoxia and Periodic Breathing in the Neonate

ABSTRACT. The influence of sleep state on hypoxia-induced periodic breathing was evaluated in full-term babies studied during the first week of life. Following exposure to 15% O₂, periodic breathing occurred in 7 of 42 babies during quiet sleep, and 5 of 20 during active sleep ( p < 0.05). The median levels of transcutaneous pO₂ at which periodic breathing occurred during hypoxia, and was abolished on reoxygenation were similar in each sleep state. The median duration of periodic apnoea was significantly greater in quiet than active sleep. In 7 babies the occurrence of periodic breathing during hypoxia was accompanied by a change in sleep state. This was probably coincidental in 3 cases, but in the other 4 babies hypoxia may have induced both the change in state and breathing pattern.     

Neonatal encephalopathy and socioeconomic status: population-based case-control study

OBJECTIVE: To investigate the association between maternal socioeconomic status and the risk of encephalopathy in full-term newborns. DESIGN: Population-based case-control study. SETTING: Washington State births from 1994 through 2002 recorded in the linked Washington State Birth Registry and Comprehensive Hospital Abstract Reporting System. PARTICIPANTS: Cases (n = 1060) were singleton full-term newborns with Comprehensive Hospital Abstract Reporting System International Classification of Diseases, Ninth Revision diagnoses of seizures, birth asphyxia, central nervous system dysfunction, or cerebral irritability. Control cases (n = 5330) were singleton full-term newborns selected from the same database. Main Exposures Socioeconomic status was defined by median income of the census tract of the mother's residence, number of years of maternal educational achievement, or maternal insurance status. MAIN OUTCOME MEASURES: Odds ratios estimating the risk of encephalopathy associated with disadvantaged socioeconomic status were calculated in 3 separate analyses using multivariate adjusted logistic regression. RESULTS: Newborns of mothers living in neighborhoods in which residents have a low median income were at increased risk of encephalopathy compared with newborns in neighborhoods in which residents have a median income more than 3 times the poverty level (adjusted odds ratio, 1.9; 95% confidence interval, 1.5-2.3). There was also a trend for increasing risk of encephalopathy associated with decreasing neighborhood income (P<.001). Newborns of mothers with less than 12 years of educational achievement had a higher risk of encephalopathy compared with newborns of mothers with more than 16 years of educational achievement (adjusted odds ratio, 1.7; 95% confidence interval, 1.3-2.3). Newborns of mothers receiving public insurance also had a higher risk of encephalopathy compared with newborns of mothers who have commercial insurance (adjusted odds ratio, 1.4; 95% confidence interval, 1.2-1.7). CONCLUSION: Disadvantaged socioeconomic status was independently associated with an increased risk of encephalopathy in full-term newborns. These findings suggest that a mother's socioeconomic status may influence the risk of encephalopathy for her full-term newborn.     

Progressive shortening of the periodic breathing cycle duration in normal infants

Ten normal full-term neonates were monitored by oxycardiorespirography in hospital during the 1st wk of life, and subsequently at home at 4, 8, and 12 wk of age in a longitudinal study of the duration of the periodic breathing cycle during spontaneous sleep. Periodic breathing was observed in 25 of the 40 studies, with a total of 168 epochs of periodicity noted. Eighty-four percent of the periodic epochs occurring during nonrapid eye movements were preceded by a sigh, body movements, or sleep state transition, compared with 41% during rapid eye movements (p less than 0.005). There was a progressive reduction in the periodic breathing cycle duration, which fell significantly between the 1st and 4th wk, in both sleep states, (p less than 0.001). There was a further significant fall between 4 and 12 wk in nonrapid eye movement sleep (p less than 0.05), and there was no significant difference between sleep states at any postnatal age. The overall change in the duration of the periodic cycle, for both sleep states combined, was from 15.0 +/- 3.6 s at less than 1 wk to 12.4 +/- 1.8 s at 12 wk of age. The periodic breathing cycle duration progressively shortens over the first 3 months of life. We postulate that this shortening may be useful indicator of peripheral chemoreceptor maturation over this time period.     

Breathing patterns and heart rates at ages 6 weeks and 2 years.

Forty-two randomly selected, full-term, healthy infants underwent 24-hour electrocardiographic recordings and breathing movements at about ages 6 weeks (median age, 43 days; range, 34 to 61 days) and 2 years (median age, 26 months; range, 21 to 35 months). The number and duration of apneic pauses of 3.6 seconds or longer were analyzed. Periodic apnea was defined as a sequence of three or more apneic pauses, each separated by fewer than 20 breaths. All other apneic pauses were defined as isolated. Median heart rates and respiratory rates, which were measured during regular breathing, decreased from 137/min and 35/min to 98/min and 21/min, respectively. The total duration of periodic apnea remained unchanged (median, 0.06 min/h vs 0.05 min/h). Although the median frequency of all isolated apneic pauses decreased from 3.6/h to 2.5/h, the number of those that were longer than 6 seconds increased from 0.37/h to 0.80/h, leading to an increase in the proportion of these pauses, among all isolated apneic pauses, from 10% at age 6 weeks to 32% at age 2 years. Only one apneic pause in one infant at age 6 weeks, but eight pauses in six children at age 2 years, were longer than 15 seconds. A knowledge of such normal variability in the duration of apneic pauses in older infants and young children is essential for the interpretation of pneumograms and alarms while monitoring breathing movements.     

Esophageal function of infants with sudden infant death--risk

In 24 patients at risk for SIDS (12 infants with a near miss event and 12 infants with apnea and perioral cyanosis during sleep) respiratory and esophageal function were investigated by impedance pneumography (IP) and esophageal manometry combined with simultaneous pH-monitoring (EMPH). Both groups had ad early pathologic breathing pattern, but did not show any difference in the recorded parameters (number of apneic spells, longest apneic spell, apneic spells longer than 10 seconds, transcutaneous oxygen pressure, mean apnea time). Near miss infants had about 50% more manometric refluxes (15.4 +/- 1.3) than the apnea/cyanosis group (9.9 +/- 2.2). This difference was mainly caused by a significant rise of reflux episodes without pH-change (near miss 8.5 +/- 3.1 versus 2.9 +/- 1.4 in apnea/cyanosis infants). Furthermore, propulsive peristaltic properties after induced swallows were more disturbed in the near miss group (3.3 +/- 1.0 versus 6.1 +/- 1.9). On the other hand, the apnea cyanosis group showed significantly more pH-drops under 4 (6.8 +/- 2.3 vs 2.4 +/- 0.7), which might be due to a more rapid clearance of neutralising milk from the stomach in these infants. In conclusion the study showed that infants with a near miss event in the anamnesis suffer from a more pathologic esophageal motor function when compared with infants with apneic spells and cyanosis during sleep. Near miss infants are also considered to have a delay of gastric clearance.     

Immunologic findings in the newborn infant. II. Studies of humoral immunity, reference values of immunologic studies in the newborn infant

After dealing with cellular immune aspects in the first part of the paper the authors describe in the second part the state of humoral immunity in healthy full-term newborns aged one to three days. The number of complementreceptor lymphocytes was 17.0 +/- 8.9% or 0.75 +/- 0.51 (mean +/- S.D.) respectively, with the EAC-rosette method. The percentage value equalled that of adults but the absolute count is higher. Using the immunodiffusion method IgA was detectable in 4 out of 132 newborns only 8.86 +/- 2.52 g/l (mean +/- S.D.) was measured as an average IgG concentration. With regard to the IgM content the values often exceeded 0.30 g/l in newborns of mothers who had been suffering from pre-eclampsia. Their mean value of 0.35 +/- 0.21 g/l, too, was significantly higher than 0.13 +/- 0.08 in the resting infants. Raised IgM values frequently coincided with high spontaneous transformation activities in lymphocyte cultures. The possible causes are discussed. Complement C3-component was measured on average with 0.78 +/- 0.18 g/l and C4-component with 0.34 +/- 0.11 g/l. When calculating reference values for newborns the results of infants with maternal pre-eclampsia have been omitted.     

Oral breathing in newborn infants

Newborn infants are considered obligate nasal breathers, hence dependent on a patent nasal airway for ventilation. The conditions under which oral breathing could occur and the contribution of oral ventilation to total ventilation were studied in 30 healthy term infants (aged 1 to 3 days). Nasal and oral airflow were measured using two resistance-matched pneumotachometers, and heart rate, tcPO2, etCO2, and sleep state were continuously recorded. In three of 10 infants studied in undisturbed sleep, spontaneous oronasal breathing was noted during both active and quiet sleep (mean duration 19 +/- 25 minutes), the distribution of tidal volume being 70% +/- 12% nasal and 30% +/- 12% oral. Episodes of oronasal breathing were also observed after crying in six infants (mean duration 21 +/- 19 seconds). In an additional 20 infants, multiple 15-second end-expiratory nasal occlusions were performed; eight (40%) of these infants initiated and sustained oral breathing in response to nasal occlusion. Respiratory rate, tidal volume, heart rate, and tcPO2 did not change when oral breathing occurred in response to nasal occlusion, although minute ventilation decreased from 265 to 199 ml/min/kg (P less than 0.05). These results demonstrate that newborn infants may use the oral airway for ventilation, both spontaneously and in response to complete nasal occlusion.     

Oesophageal motor activity and sleep state in the newborn human infant

Oesophageal pressure and ventilation were recorded during sleep in healthy full-term neonates with sleep state defined by one of two methods; in 35 infants by combined behavioural and electroencephalographic criteria, and in a further 13 infants by behavioural criteria alone. Spontaneous oesophageal contractions occurred in all infants during active sleep but rarely during quiet sleep. The transition from active to quiet sleep was accompanied by a gradual reduction in the frequency of these contractions. Oesophageal contractions associated with sighs and contractions shortly following interruption of breathing suggestive of swallowing were also significantly more common in active sleep. In 13 infants who showed periodic breathing the same differences in prevalence of spontaneous oesophageal contractions in each sleep state were observed.     

A longitudinal study on the effects of maternal smoking and secondhand smoke exposure during pregnancy on neonatal neurobehavior

Maternal smoking during pregnancy is one of the most modifiable causes of morbidity and mortality for both pregnant women and their fetuses. The long-term effects of prenatal exposure to smoke on child behavior and development have been the subject of more extensive research than have the short-term effects. Therefore, the aim of this work is to examine the effects of smoke exposure during pregnancy on neonatal behavior, including in our study a group of mothers exposed to secondhand smoke. The behavior of 282 healthy full-term newborns was assessed using the Neonatal Behavior Assessment Scale (NBAS) at 48-72 h of life. Sixty-two mothers smoked during pregnancy (no mother smoked more than 15 cig/day) and 17 were exposed to secondhand smoke. After adjusting for socio-demographic and obstetric factors, both newborns whose mothers smoked and those whose mothers were exposed to secondhand smoke showed significantly lower scores in the habituation cluster than non-smoking mothers. Exposure to secondhand smoke was also related to lower motor system cluster scores as well as some supplementary items and the newborns of smoking mothers showed significantly lower scores in the state regulation cluster and in some items of the state organization cluster than the newborns of non-smoking mothers. We conclude that active and passive smoking during pregnancy affects several aspects of neurobehavioral development, regardless of socio-demographic, obstetric and pediatric factors.     

Arousal from sleep during rapidly developing hypoxemia in lambs

Arousal is an important protective response that may prevent severe hypoxemia and death during sleep. However, very little is known about arousal from sleep in response to respiratory stimuli in newborns. Experiments were therefore done to investigate the arousal response from sleep to rapidly developing hypoxemia in eight lambs. Each lamb was anesthetized and instrumented for recordings of electrocorticogram, electrooculogram, nuchal and diaphragm electromyograms, and measurements of arterial hemoglobin oxygen saturation. A tracheotomy was done and a tracheostomy tube placed in the trachea so that the fraction of inspired oxygen could be changed quickly. No sooner than 3 days after surgery, measurements were made in quiet sleep and active sleep (AS) during 30-s control periods when the animals were breathing 21% oxygen and during experimental periods of hypoxemia when the animals were breathing either 10, 5, or 0% oxygen in nitrogen. During quiet sleep, arousal occurred at similar arterial hemoglobin oxygen saturations (81 +/- 6% on 10% O2, 80 +/- 5% on 5% O2 and 83 +/- 5% on 0% O2) suggesting that arousal was independent of the rate of change of arterial oxygen. However, during AS arousal occurred at different arterial hemoglobin oxygen saturations (76 +/- 6% on 10% O2, 55 +/- 11% on 5% O2, and 44 +/- 17% on 0% O2) suggesting that arousal was dependent on the rate of change of arterial oxygen. During some epochs of AS, electrocortical signs of cerebral hypoxia and primary apnea occurred before arousal. These data provide evidence that arousal from quiet sleep in response to hypoxemia occurs once an arousal threshold has been reached.(ABSTRACT TRUNCATED AT 250 WORDS)     

Adrenocorticotrophic hormone during the first day of life

The plasma concentration of ACTH (by radioimmunoassay) was measured in 56 healthy parturients and their newborns. Umbilical cord and maternal venous blood were collected immediately after delivery. In addition one venous blood sample was taken from 50 newborns at the age of 15, 30, 60 min, 2, 6, 12, or 24 h.The maternal and cord plasma ACTH levels were higher than the levels in healthy nonpregnant women. There are no differences between the mean maternal (226±146 pg/ml) and cord (226±147 pg/ml) values of ACTH.The high ACTH levels of cord plasma remain unchanged for 30 min, decrease significantly during the 1–6 h after birth, because of the elimination process of the circulated foetal ACTH, and increase over the next 12–24 h and slightly thereafter indicating an initiation of neonatal pituitary ACTH secretion.The plasma ACTH level in the mothers with membranes ruptured for 1–5 h was significantly (P<0.05) higher compared with that in the mothers with membranes ruptured for less than 1 h. However, the duration of ruptured membranes appeared to have no effect on the cord blood ACTH level.     

Functional residual capacity and sleep states in the premature newborn

Functional residual capacity (FRC) variations in relation to sleep state changes were studied in 11 premature infants with birth weights of 1.68 +/- 0.48 kg and gestational ages of 32.7 +/- 2.2 weeks (mean +/- SD). Helium dilution was used to measure FRC, and sleep states were identified using neurophysiologic criteria. No significant difference in FRC could be demonstrated between data collected during active sleep (AS) and quiet sleep. However a relationship was shown between AS and paradoxical breathing (p less than 0.02) and between AS and irregular breathing (p less than 0.05). Several factors are discussed which might explain the discrepancy between the present data in premature infants and the previously published data in term infants. (1) Neurophysiologic identification of sleep states does not include breathing pattern whereas behavioral identification does. It is therefore possible that lung volume changes are related to breathing pattern changes and not to sleep state changes per se. (2) Maturational changes may occur among the mechanisms which control FRC, leading to a progressive stabilisation of FRC, the variation of which could become related to sleep state changes.     

Do lung volumes change with sleep state in the neonate?

We have studied 12 healthy full-term babies, mean age 3.2 days, using physiological criteria — EEG, electro-oculogram, electromyogram, respiratory regularity and visible movement — to assess sleep state, and a respiratory jacket to record changes in functional residual capacity (FRC). A total of 593 min of sleep data were analysed. Of the recordings, 39% were scored as quiet sleep, 40% as active and 21% as indeterminate sleep. The mean maximum variation in FRC overall was 29 ml (SD±15.4 ml). Examination of these figures showed that FRC variations during sleep state changes were smaller than those seen within a defined sleep state. We conclude that changes in sleep state are not associated with variations in FRC.Abbreviations EMG electromyogram - EOG electro-oculogram - FRC functional residual capacity     

Use of oxygen therapy during labour and acid-base status in the newborn

The effect of supplemental maternal oxygen therapy on acid-base status has for years been a subject of controversies. There is still no general agreement about oxygen administration in pregnancy or in labour. Many clinicians believe that in normal pregnancy maternal oxygen treatment has merely negligible, if any, influence on the foetus. Maternal oxygen therapy has frequently been suggested when oxygen supply to the foetus was insufficient, viz. in antepartum or intrapartum hypoxia. The aim of this study was to determine whether a brief maternal hyperoxygenation during caesarean section or during the second stage of normal delivery affects cord blood acid-base status measured at birth. Patients with uneventful term pregnancy admitted to the delivery room in spontaneous labour or indicated for elective caesarean section were matched and prospectively ascribed to the control or treatment group. The latter received 60% oxygen for ca. 10 min at 15 L/min by a face mask. We studied 41 normal term infants of healthy mothers (24 from caesarean sections, the remaining 17 delivered vaginally). The control group consisted of normal newborns chosen according to the same criteria except that their mothers had no oxygen supplementation. Immediately after delivery, umbilical cord paired blood samples were drawn. Arterial and venous specimens were analysed for blood gases and acid-base balance parameters. Statistical analysis assisted by computer software was performed using Mann-Whitney U test. A p value < 0.05 was considered significant. All tested parameters related to the acid-base status and blood gases were similar in the treatment and control groups. Concluding, a short period of maternal hyperoxygenation either in the second stage of vaginal spontaneous delivery or during caesarean section did not affect umbilical cord blood acid-base status measured at birth.