Effects of a transition home program on preterm infant emergency room visits within 90 days of discharge.

OBJECTIVE: To evaluate effects of a transition home program (THP) and risk factors on emergency room (ER) use within 90 days of discharge for preterm (PT) infants <37 weeks gestation. STUDY DESIGN: This is a prospective 3-year cohort study of 804 mothers and 954 PT infants. Mothers received enhanced neonatal intensive care unit transition support services until 90 days postdischarge. Regression models were run to identify the effects of THP implementation year and risk factors on ER visits. RESULTS: Of the 954 infants, 181 (19%) had ER visits and 83/181 (46%) had an admission. In regression analysis, THP year 3 vs year 1 and human milk at discharge were associated with decreased risk of ER visits, whereas increased odds was associated with non-English speaking, maternal mental health disorders and bronchopulmonary dysplasia. CONCLUSION: Enhanced THP services were associated with a 33% decreased risk of all ER visits by year 3. Social and environmental risk factors contribute to preventable ER visits.

Postpartum contraception needs of women with preterm infants in the neonatal intensive care unit.

OBJECTIVES: To evaluate postpartum contraception experiences of mothers with premature infants in the neonatal intensive care unit (NICU), their knowledge of risk factors for preterm delivery and their interest in a family planning clinic located near the NICU. STUDY DESIGN: This is a cross-sectional survey of English or Spanish-speaking women 18 or older whose premature neonate had been in the NICU for 5 days or more in a current stable condition. RESULTS: A total of 95 women were interviewed at a median of 2.7 weeks postpartum (range 0.6-12.9). Approximately 75% of women were currently using or planning to use contraception, with 33% using less effective methods. Half of women reported they would obtain contraception at a family planning clinic near the NICU. Only 32% identified a short interpregnancy interval as a risk factor for preterm delivery. CONCLUSION: Lack of knowledge of short interpregnancy interval as a risk factor for a future preterm delivery highlights the need to address postpartum contraception education and provision in this high-risk population.

Do currently recommended Bayley-III cutoffs overestimate motor impairment in infants born <27 weeks gestation?

OBJECTIVE: To determine whether a Bayley-III motor composite score of 85 may overestimate moderate-severe motor impairment by analyzing Bayley-III motor components and developing cut-point scores for each. STUDY DESIGN: Retrospective study of 1183 children born <27 weeks gestation at NICHD Neonatal Research Network centers and evaluated at 18-22 months corrected age. Gross Motor Function Classification System determined gross motor impairment. Statistical analyses included linear and logistic regression and sensitivity/specificity. RESULTS: Bayley-III motor composite scores were strong indicators of gross/fine motor impairment. A motor composite cut-point of 73 markedly improved the specificity for identifying gross and/or fine motor impairment (94% compared with a specificity of 76% for the proposed new cut-point of 85). A Fine Motor Scaled Score <3 differentiated mild from moderate-severe fine motor impairment. CONCLUSIONS: This study indicates that a Bayley-III motor composite score of 85 may overestimate impairment. Further studies are needed employing term controls and longer follow-up.

Characteristics of extremely low-birth-weight infant survivors with unimpaired outcomes at 30 months of age.

OBJECTIVE: To evaluate characteristics of unimpaired outcome in extremely low-birth-weight (ELBW) survivors. STUDY DESIGN: ELBW infants (n=714) with 30 months' assessments were analyzed. Logistic regression was used to develop a model for the binary outcome of unimpaired versus impaired outcome. RESULT: Thirty-three percent of infants had an unimpaired outcome. Seventeen percent of ELBW survivors had a Bayley II Mental Developmental Index score of ≥ 101 and 2% had a score of ≥ 116. Female gender, use of antenatal steroids (ANS), maternal education ≥ high school and the absence of major neonatal morbidities were independent predictors of unimpaired outcome. The likelihood of an unimpaired outcome in the presence of major neonatal morbidities was higher in infants exposed to ANS. CONCLUSION: The majority of unimpaired ELBW survivors had cognitive scores shifted toward the lower end of the normal distribution. Exposure to ANS was associated with higher likelihood of an unimpaired outcome in infants with major neonatal morbidities.

Blood stream infection is associated with altered heptavalent pneumococcal conjugate vaccine immune responses in very low birth weight infants.

OBJECTIVE: Sepsis in older children and adults modifies immune system function. We compared serotype-specific antibody responses to heptavalent pneumococcal conjugate vaccine (PCV7) in very low birth weight infants (<1500 g,VLBWs) with and without blood stream infection (BSI) during their birth hospitalization. STUDY DESIGN: Retrospective analysis of prospectively collected data for the Neonatal Research Network study of PCV7 responses among VLBWs. Infants received PCV7 at 2, 4 and 6 months after birth with blood drawn 4 to 6 weeks after third dose. Serotype antibodies were compared between infants with or without a history of BSI. Regression models were constructed with BW groups and other confounding factors identified in the primary study. RESULT: In all, 244 infants completed the vaccine series and had serum antibody available; 82 had BSI. After adjustment, BSI was not associated with reduced odds of serum antibody 0.35 µg ml(-1). CONCLUSION: BSI was not associated with reduced odds of World Health Organization-defined protective PCV7 responses in VLBWs.

Efficacy of phototherapy devices and outcomes among extremely low birth weight infants: multi-center observational study.

OBJECTIVE: Evaluate the efficacy of phototherapy (PT) devices and the outcomes of extremely premature infants treated with those devices. STUDY DESIGN: This substudy of the National Institute of Child Health and Human Development Neonatal Research Network PT trial included 1404 infants treated with a single type of PT device during the first 24±12 h of treatment. The absolute (primary outcome) and relative decrease in total serum bilirubin (TSB) and other measures were evaluated. For infants treated with one PT type during the 2-week intervention period (n=1223), adjusted outcomes at discharge and 18 to 22 months corrected age were determined. RESULT: In the first 24 h, the adjusted absolute (mean (±s.d.)) and relative (%) decrease in TSB (mg dl(-1)) were: light-emitting diodes (LEDs) -2.2 (±3), -22%; Spotlights -1.7 (±2), -19%; Banks -1.3 (±3), -8%; Blankets -0.8 (±3), -1%; (P<0.0002). Some findings at 18 to 22 months differed between groups. CONCLUSION: LEDs achieved the greatest initial absolute reduction in TSB but were similar to Spots in the other performance measures. Long-term effects of PT devices in extremely premature infants deserve rigorous evaluation.

The intrinsic connectivity distribution: a novel contrast measure reflecting voxel level functional connectivity.

Resting-state fMRI (rs-fMRI) holds promise as a clinical tool to characterize and monitor the phenotype of different neurological and psychiatric disorders. The most common analysis approach requires the definition of one or more regions-of-interest (ROIs). However this need for a priori ROI information makes rs-fMRI inadequate to survey functional connectivity differences associated with a range of neurological disorders where the ROI information may not be available. A second problem encountered in fMRI measures of connectivity is the need for an arbitrary correlation threshold to determine whether or not two areas are connected. This is problematic because in many cases the differences in tissue connectivity between disease groups and/or control subjects are threshold dependent. In this work we propose a novel voxel-based contrast mechanism for rs-fMRI, the intrinsic connectivity distribution (ICD), that neither requires a priori information to define a ROI, nor an arbitrary threshold to define a connection. We show the sensitivity of previous methods to the choice of connection thresholds and evaluate ICD using a survey study comparing young adults born prematurely to healthy term control subjects. Functional connectivity differences were found in hypothesized language processing areas in the left temporal-parietal areas. In addition, significant clinically-relevant differences were found between preterm and term control subjects, highlighting the importance of whole brain surveys independent of a priori information.

Expressive vocabulary of children with hearing loss in the first 2 years of life: impact of early intervention.

OBJECTIVE: The aim of this study was to determine the expressive vocabulary of children with hearing loss (HL) enrolled in early intervention (EI) ≤ 3 vs >3 months in the first 24 months and to compare with hearing controls. It was hypothesized that the number of words produced would be higher for children with HL enrolled in EI ≤ 3 vs >3 months. STUDY DESIGN: This is a prospective longitudinal matched cohort study. RESULT: The children with HL produced fewer words than the children with hearing. In addition, children with HL enrolled in EI ≤ 3 months had a larger expressive vocabulary percentile score compared with children with HL enrolled >3 months. Children with mild HL enrolled in EI ≤ 3 months had the greatest growth in vocabulary between 12 to 16 and 18 to 24 months. CONCLUSION: Although multiple factors are associated with expressive vocabulary growth of children with HL, enrollment in EI ≤ 3 months has sustained beneficial effects on expressive vocabulary at 18 to 24 months.

Influence of clinical status on the association between plasma total and unbound bilirubin and death or adverse neurodevelopmental outcomes in extremely low birth weight infants.

OBJECTIVES: To assess the influence of clinical status on the association between total plasma bilirubin and unbound bilirubin on death or adverse neurodevelopmental outcomes at 18-22 months corrected age in extremely low birth weight infants. METHOD: Total plasma bilirubin and unbound bilirubin were measured in 1101 extremely low birth weight infants at 5 +/- 1 days of age. Clinical criteria were used to classify infants as clinically stable or unstable. Survivors were examined at 18-22 months corrected age by certified examiners. Outcome variables were death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss, and death prior to follow-up. For all outcomes, the interaction between bilirubin variables and clinical status was assessed in logistic regression analyses adjusted for multiple risk factors. RESULTS: Regardless of clinical status, an increasing level of unbound bilirubin was associated with higher rates of death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss and death before follow-up. Total plasma bilirubin values were directly associated with death or neurodevelopmental impairment, death or cerebral palsy, death or hearing loss, and death before follow-up in unstable infants, but not in stable infants. An inverse association between total plasma bilirubin and death or cerebral palsy was found in stable infants. CONCLUSIONS: In extremely low birth weight infants, clinical status at 5 days of age affects the association between total plasma bilirubin and death or adverse neurodevelopmental outcomes at 18-22 months of corrected age. An increasing level of UB is associated a higher risk of death or adverse neurodevelopmental outcomes regardless of clinical status. Increasing levels of total plasma bilirubin are directly associated with increasing risk of death or adverse neurodevelopmental outcomes in unstable, but not in stable infants.

Seven-month developmental outcomes of very low birth weight infants enrolled in a randomized controlled trial of delayed versus immediate cord clamping.

OBJECTIVE: The results from our previous trial revealed that infants with delayed cord clamping (DCC) had significantly lesser intraventricular hemorrhage (IVH) and late-onset sepsis (LOS) than infants with immediate cord clamping (ICC). A priori, we hypothesized that infants with DCC would have better motor function by 7 months corrected age. STUDY DESIGN: Infants between 24 and 31 weeks were randomized to ICC or DCC and follow-up evaluation was completed at 7 months corrected age. RESULT: We found no differences in the Bayley Scales of Infant Development (BSID) scores between the DCC and ICC groups. However, a regression model of effects of DCC on motor scores controlling for gestational age, IVH, bronchopulmonary dysplasia, sepsis and male gender suggested higher motor scores of male infants with DCC. CONCLUSION: DCC at birth seems to be protective of very low birth weight male infants against motor disability at 7 months corrected age.

Fluid regimens in the first week of life may increase risk of patent ductus arteriosus in extremely low birth weight infants.

BACKGROUND: High fluid volumes may increase neonatal morbidity. However, evidence supporting fluid restriction is inconclusive and restricting fluids may restrict caloric intake. OBJECTIVE: To determine if higher fluid intake was associated with increased risk of patent ductus arteriosus (PDA) or bronchopulmonary dysplasia (BPD) in extremely low birth weight (ELBW) infants. STUDY DESIGN: A total of 204 ELBW (170 ml kg(-1) day(-1)) in the first days of life is associated with increased risk of PDA.

Association between maternal and child leptin levels 9 years after pregnancy complicated by gestational diabetes.

Obesity is a state of relative leptin resistance, and obesity in childhood is associated with an increased incidence of type 2 diabetes in later life. Offspring of mothers with gestational diabetes mellitus (GDM) are at increased risk of obesity. A cohort consisting of 64 mothers, 33 GDM and 31 controls screened for diabetes during the index pregnancy together with their 9-year-old offspring were studied. Our hypotheses were: 1) an elevated child leptin is associated with elevated maternal leptin in GDM mothers 9 years post delivery; and 2) child leptin at 9 years serves as a marker for incipient insulin resistance. By univariate analyses, child leptins were only significantly correlated with maternal leptins among the offspring of GDMs (OGDM) (r = 0.59; p = 0.001). By multivariate analyses, child leptin for the total study group was significantly associated with child body mass index (BMI) (R(2) = 0.65; p < 0.0001), child fasting insulin (R(2) = 0.08; p = 0.03), and female gender (R(2) = 0.28; p = 0.001). In addition, among OGDM child leptin was associated with maternal leptin (R(2) = 0.14; p = 0.005). Our results suggest that there is an association between maternal and child leptin levels 9 years after a pregnancy complicated by gestational diabetes.

Antenatal therapies and the developing brain.

This chapter presents a review of basic science and human studies of two commonly used pharmacologic agents (antenatal steroids and magnesium sulfate), in pregnancies at risk of preterm delivery, and examines the effects of these therapies on the developing brain. Very low birthweight (VLBW) infants are known to be at risk of both short-term and long-term neurodevelopmental sequelae; therefore, an understanding of the mechanisms contributing to both neuroprotective and neurotoxic effects of antenatal therapies on the immature brain and potential effects on long-term outcome are critical. Although the short-term beneficial effects of a single course of antenatal steroids are well documented, the experimental animal literature suggests detrimental effects on neurodevelopment of multiple doses. In addition, clinical studies of repeat doses suggest a negative impact on head and brain growth. The animal and human data on the effects of MgSO(4)are also mixed with both beneficial effects or no effects on neurodevelopment. This review will discuss the potential impact of single versus multiple doses and timing of doses on the brain.

Comparison of costs and referral rates of 3 universal newborn hearing screening protocols.

OBJECTIVE: To investigate the costs and referral rates of 3 universal newborn hearing screening programs: transient evoked otoacoustic emissions (TEOAE), automated auditory brainstem response (AABR), and a combination, two-step protocol in which TEOAE and AABR are used. STUDY DESIGN: Clinical outcomes (referral rates) from 12,081 newborns at 5 sites were obtained by retrospective analysis. Prospective activity-based costing techniques (n = 1056) in conjunction with cost assumptions were used to analyze the costs based on an assumed annual birth rate of 1500 births. RESULTS: Referral rates differed significantly among the 3 screening protocols (AABR, 3.21%; two-step, 4.67%; TEOAE, 6.49%; P <.01), with AABR achieving the best referral rate at discharge. Although AABR had the lowest referral rate at discharge and the highest pre-discharge costs, the total pre- and post-discharge costs per infant screened (AABR, $32.81; two-step, $33.05; TEOAE, $28.69) and costs per identified child (AABR, $16,405; two-step, $16,527; TEOAE, $14,347) were similar among programs. CONCLUSION: Although AABR incurs higher costs during pre-discharge screening, it has lower referral rates than either the TEOAE or two-step program. As a result, the total costs of newborn hearing screening and diagnosis are similar among the 3 methods studied.

Maternal worry about neonatal hearing screening.

OBJECTIVE: To identify and compare the prevalence and degree of maternal worry about neonatal hearing screening at the time of an initial neonatal hearing screen and rescreen in 1997 and 1999. STUDY DESIGN: We report on a prospective cross-sectional investigation of maternal worry about newborn hearing screening. Demographic data, maternal knowledge of hearing screening, and degree of maternal worry were collected on 307 mothers at the time of the neonatal screen and 40 mothers at the time of the rescreen. RESULTS: Degree of maternal worry was significantly greater at the rescreen compared to the screen. Mothers who reported greater worry at the time of the screen were more likely to be socioeconomically disadvantaged. Although maternal knowledge about hearing screening increased between the two time periods, degree of worry remained unchanged. CONCLUSION: Efforts to minimize the neonatal false-positive hearing screen rates and to educate mothers about hearing screening are indicated to minimize unnecessary worry.

Identification of neonatal hearing impairment: a multicenter investigation.

OBJECTIVES: This article describes the design of a multicenter study sponsored by the National Institutes of Health. The purpose of this study was to determine the accuracy of three measures of peripheral auditory system status (transient evoked otoacoustic emissions, distortion product otoacoustic emissions, and auditory brain stem responses) applied in the perinatal period for predicting behavioral hearing status at 8 to 12 mo corrected age. The influences of the infant's medical status, the test environment, and test and response parameters on test performance were examined. DESIGN: Seven institutions participated in this study. There were 7179 infants evaluated in the perinatal period. All graduates of the neonatal intensive care unit (4478) and well babies with one or more risk factor for hearing loss (353) were targeted for follow-up testing using visual reinforcement audiometry (VRA) at 8 to 12 mo corrected age. Well babies without any risk indicators (N = 2348) were not targeted for follow-up VRA testing. However, 80 of these well babies did not pass the screening protocol and thus were targeted for follow-up VRA testing as well. Perinatal test performance was evaluated using the VRA data as the "gold standard." RESULTS: The results of this study are described in a series of 11 articles following this introductory article. CONCLUSIONS: The evaluation of newborn hearing tests required a longitudinal study in which newborn test results were compared with a gold standard based on behavioral audiometric assessment. Such an evaluation was possible because all newborns, passes as well as refers, were followed up long enough to permit reliable behavioral measurements. In addition, prenatal, perinatal, and maternal history information, test environment, and test parameter information were collected to provide data that led to a complete description of factors affecting test outcomes. All of these data were obtained in a sample of sufficient ethnic, medical, and geographic diversity in efforts to increase the generalizability of the results. Finally, the data were combined in a relational data base to examine the factors that influence test performance. Specific information related to these issues is presented in the articles that follow.

Identification of neonatal hearing impairment: experimental protocol and database management.

OBJECTIVE: The purposes of this article are to describe the overall protocol for the Identification of Neonatal Hearing Impairment (INHI) project and to describe the management of the data collected as part of this project. A well-defined protocol and database management techniques were needed to ensure that data were 1) collected accurately and in the same way across sites; 2) maintained in a database that could be used to provide feedback to individual sites regarding enrollment and the extent to which the protocol was complete on individual subjects; and 3) available to answer project questions. This article describes techniques that were used to meet these needs. DESIGN: This study was a prospective, randomized study that was designed to evaluate auditory brain stem responses, transient evoked otoacoustic emissions, and distortion product otoacoustic emissions as hearing-screening tools, and to relate neonatal test findings to hearing status, defined by visual reinforcement audiometry at 8 to 12 mo of age. Measures of middle-ear function also were obtained at some sites as part of the neonatal test battery. In addition, other clinical and demographic data were gathered to determine the extent to which factors, other than auditory status, influenced test behavior. Three groups were evaluated: neonatal intensive care unit (NICU) infants (those who spent 3 or more days in a NICU), well babies with risk factors for hearing loss, and well babies without risk factors. Six centers participated in the trial. The testers for the project included audiologists, technicians, audiology graduate students, and medical research staff. The same computerized neonatal test program was applied at each center. This program generated the neonatal test database automatically. Clinical and demographic data were collected by means of concise data collection forms and were entered into a database at each site. After the neonatal test, subjects from the NICU and at-risk well babies were evaluated with visual reinforcement audiometry starting at 8 to 12 mo of age. All data were electronically transmitted to the core site where they were merged into one overall database. This database was exercised to provide feedback and to identify discrepancies throughout the course of the study. In its final form, it served as the database on which all analyses were performed. RESULTS AND CONCLUSION: The protocol was a departure from typical hearing screening procedures in terms of 1) its regimented application of three screening measures; 2) the detailed information that was obtained regarding subject clinical and demographic factors; and 3) its application of the same procedures across six centers having diverse geographic location and subject demographics. A learning curve for successfully executing the study protocols was observed. Throughout the study, monthly reports were generated to monitor subject enrollment, check for data completeness, and to perform data integrity checks. In combination with monthly data reports and checks that occurred throughout the progression of the study, miscellaneous data audits were performed to check accuracy of neonatal testing programs and to cross-check information entered in the clinical and demographic database. The data management techniques used in this project helped to ensure the quality of the data collection process and also allowed for detailed analyses once data were collected. This was particularly important because it enabled us to evaluate not only the performance of individual measures as screening tools, but also permitted an evaluation of the influence of other variables on screening test results.

Identification of neonatal hearing impairment: distortion product otoacoustic emissions during the perinatal period.

OBJECTIVES: 1) To describe distortion product otoacoustic emission (DPOAE) levels, noise levels and signal to noise ratios (SNRs) for a wide range of frequencies and two stimulus levels in neonates and infants. 2) To describe the relations between these DPOAE measurements and age, test environment, baby state, and test time. DESIGN: DPOAEs were measured in 2348 well babies without risk indicators, 353 well babies with at least one risk indicator, and 4478 graduates of neonatal intensive care units (NICUs). DPOAE and noise levels were measured at f2 frequencies of 1.0, 1.5, 2.0, 3.0, and 4.0 kHz, and for primary levels (L1/L2) of 65/50 dB SPL and 75/75 dB SPL. Measurement-based stopping rules were used such that a test did not terminate unless the response was at least 3 dB above the mean noise floor + 2 SDs (SNR) for at least four of five test frequencies. The test would terminate, however, if these criteria were not met after 360 sec. Baby state, test environment, and other test factors were captured at the time of each test. RESULTS: DPOAE levels, noise levels and SNRs were similar for well babies without risk indicators, well babies with risk indicators, and NICU graduates. There was a tendency for larger responses at f2 frequencies of 1.5 and 2.0 Hz, compared with 3.0 and 4.0 kHz; however, the noise levels systematically decreased as frequency increased, resulting in the most favorable SNRs at 3.0 and 4.0 kHz. Response levels were least and noise levels highest for an f2 frequency of 1.0 kHz. In addition, test time to achieve automatic stopping criteria was greatest for 1.0 kHz. With the exception of "active/alert" and "crying" babies, baby state had little influence on DPOAE measurements. Additionally, test environment had little impact on these measurements, at least for the environments in which babies were tested in this study. However, the lowest SNRs were observed for infants who were tested in functioning isolettes. Finally, there were some subtle age affects on DPOAE levels, with the infants born most prematurely producing the smallest responses, regardless of age at the time of test. CONCLUSIONS: DPOAE measurements in neonates and infants result in robust responses in the vast majority of ears for f2 frequencies of at least 2.0, 3.0 and 4.0 kHz. SNRs decrease as frequency decreases, making the measurements less reliable at 1.0 kHz. When considered along with test time, there may be little justification for including an f2 frequency at 1.0 kHz in newborn screening programs. It would appear that DPOAEs result in reliable measurements when tests are conducted in the environments in which babies typically are found. Finally, these data suggest that babies can be tested in those states of arousal that are most commonly encountered in the perinatal period.

Identification of neonatal hearing impairment: characteristics of infants in the neonatal intensive care unit and well-baby nursery.

OBJECTIVE: The objective of this study was to describe the demographic data, medical status, and incidence of risk factors for hearing impairment in the neonatal intensive care unit (NICU) and well-baby populations in a multicenter prospective study designed to assess neonatal hearing impairment and to evaluate factors that might affect neonatal hearing test performance. DESIGN: This was a prospective multicenter study funded by the National Institutes of Health-National Institute on Deafness and Other Communication Disorders to evaluate the effectiveness of auditory brain stem response, transient evoked otoacoustic emissions, and distortion product otoacoustic emissions for newborn hearing screening. Research staff at each site obtained informed consent and detailed demographic and medical data, including information on established risk factors for hearing loss on 4478 high-risk infants cared for in the NICU, 2348 infants from the well-baby nurseries with no risk factor, and 353 infants from the well-baby nurseries with risk factors. For follow-up purposes the sample was divided further to include a subgroup called selects. Selects were either infants from the well-baby nursery who had an established risk factor for hearing impairment (N = 353) or did not pass the neonatal hearing screen protocol (N = 80). In this study, we focus on the distribution of infants by nursery and risk factors only. Particular effort was made to enroll infants with risk factors for hearing loss in both the NICU and well-baby nurseries. Descriptive analyses are used to describe characteristics of this sample. RESULTS: All 10 of the risk factors established by the Joint Committee on Infant Hearing in 1994 were identified in the NICU population. The four most common were ototoxic medications (44.4%), very low birth weight (17.8%), assisted ventilation > 5 days (16.4%), and low Apgar scores at 1 or 5 min (13.9%). In contrast, only six risk factors were present in the well-baby nurseries: family history (6.6%), craniofacial abnormalities (3.4%), low Apgar scores (2.8%), syndromes (0.5%), ototoxic medications (0.2%), and congenital infection (0.1%). CONCLUSION: These descriptive risk factor data reflect both the newborn populations at the study sites and the bias for enrolling infants at risk for hearing loss. The high-risk NICU sample reflects the characteristics typically found in graduates of the NICU. The data summarized in this study will be used to assess the relationships between risk factor and hearing test outcome.

Identification of neonatal hearing impairment: transient evoked otoacoustic emissions during the perinatal period.

OBJECTIVES: 1) To describe transient evoked otoacoustic emission (TEOAE) levels, noise levels and signal to noise ratios (SNRs) for a range of frequency bands in three groups of neonates who were tested as a part of the Identification of Neonatal Hearing Impairment multi-center consortium project. 2) To describe the relations between these TEOAE measurements and age, test environment, baby state, and test time. DESIGN: TEOAEs were measured in 4478 graduates of neonatal intensive care units (NICUs), 353 well babies with at least one risk indicator, and 2348 well babies without risk factors. TEOAE and noise levels were measured for frequency bands centered at 1.0, 1.5, 2.0, 3.0, and 4.0 kHz for a click stimulus level of 80 dB SPL. For those ears not meeting "passing" stopping criteria at 80 dB pSPL, a level of 86 dB pSPL was included. Measurement-based stopping rules were used such that a test did not terminate unless the response revealed a criterion SNR in four out of five frequency bands or no response occurred after a preset number of averages. Baby state, test environment, and other test factors were captured at the time of test. RESULTS: TEOAE levels, noise levels and SNRs were similar for NICU graduates, well babies with risk factors and well babies without risk factors. There were no consistent differences in response quality as a function of test environment, i.e., private room, unit, open crib, nonworking isolette, or working isolette. Noise level varied little across risk group, test environment, or infant state other than crying, suggesting that the primary source of noise in TEOAE measurements is infant noise. The most significant effect on response quality was center frequency. Responses were difficult to measure in the half-octave band centered at 1.0 kHz, compared with higher frequencies. Reliable responses were measured routinely at frequencies of 1.5 kHz and higher. CONCLUSIONS: TEOAEs are easily measured in both NICU graduates and well babies with and without risk factors for hearing loss in a wide variety of test environments. Given the difficulties encountered in making reliable measurements for a frequency band centered at 1.0 kHz, its inclusion in a screening program may not be justified.