Sensorineural hearing loss (SNHL) is one of the most common long-term disabilities worldwide in preterm infants, with an incidence of 0.7–17.5% for very preterm newborns (<32 weeks) [
Although many perinatal and postnatal factors associated with SNHL have been reported in the literature [
This single-center retrospective cohort study included infants admitted to the neonatal intensive care unit at Seoul National University Bundang Hospital (Seongnam, Korea) between June 2004 and January 2015. The inclusion criteria were (1) singleton birth at 23+0 to 33+6 weeks gestation, (2) survival at least 90 days after birth, (3) underwent hearing screening test, and (4) an aliquot of UCB available for analysis. We excluded twins or higher-order infants, those for whom a histologic examination of the placenta was not performed, outborn infants, and those with major structural or chromosomal abnormalities. Gestational age was calculated based on the last menstrual period and ultrasound information obtained in the first or second trimester. The study was approved by the local ethics committee of Seoul National University Bundang Hospital (IRB no. B-1006/103-102). Written informed consent was obtained from the parents of all infants (participants) whose samples and data were used for the study.
Electronic medical records on uni- or bilateral hearing screen failure of the included preterm singleton infants were reviewed by one otolaryngologist (Y. J. S.) who was blinded to the results of umbilical cord plasma analysis and the details of mothers and their infants. The conventional methods for hearing screening and the follow-up in our hospital were previously described in detail elsewhere [10, 13]. In brief, the automated auditory brainstem response (AABR) test was the most commonly performed (
The following maternal factors were extracted from the database: maternal age, parity, gestational age at admission, causes of preterm birth, delivery mode, antenatal use of medications (tocolytics, steroids, and antibiotics), and clinical diagnosis of chorioamnionitis. Perinatal/neonatal characteristics retrieved from the database were as follows: gestational age at birth, sex, birth weight, 1 and 5 min Apgar scores, pathologic diagnoses of the placenta, umbilical artery pH, neonatal blood C-reactive protein (CRP) levels and white blood cell (WBC) counts obtained within 2 hours of birth, use of surfactant, use of mechanical ventilation, proven neonatal sepsis, respiratory distress syndrome (RDS), bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), and necrotizing enterocolitis (NEC).
Clinical chorioamnionitis was diagnosed in accordance with the criteria of Gibbs et al. [
UCB samples were obtained from the umbilical vein at birth and collected into ethylenediaminetetraacetic acid tubes. The samples were centrifuged at 1500 ×
Statistical analyses were performed using SPSS version 22.0 for Windows (IBM SPSS Statistics, Chicago, IL, USA). The Shapiro-Wilk test was used to assess whether the data were normally distributed. For the bivariate analyses, Student’s
During the study period, a total of 127 women with either preterm labor (
The maternal and obstetric characteristics of the study population according to NHS test results are shown in Table
Maternal and obstetric characteristics of the study population according to newborn hearing screening test results.
Abnormal finding on newborn hearing screening test | |||
---|---|---|---|
Absent ( |
Present ( | ||
Maternal age (years) | 31.6 ± 3.6 | 31.8 ± 3.8 | 0.970 |
Nulliparity | 49 (43.8%) | 10 (66.7%) | 0.107 |
Membrane status | 0.270 | ||
Intact membranes | 49 (43.8%) | 4 (26.7%) | |
Preterm PROM | 63 (56.3%) | 11 (73.3%) | |
Cesarean delivery | 44 (39.3%) | 4 (26.7%) | 0.407 |
Antenatal corticosteroids | 107 (95.5%) | 13 (86.7%) | 0.193 |
Antenatal antibiotics | 87 (77.7%) | 13 (86.7%) | 0.737 |
Antenatal tocolytics | 91 (81.3%) | 12 (80.0%) | 1.000 |
Gestational age at admission (weeks) | 29.3 ± 3.3 | 28.4 ± 3.6 | 0.356 |
Histologic chorioamnionitis | 74 (66.1%) | 10 (66.7%) | 1.000 |
Funisitis | 22 (19.6%) | 7 (46.7%) | 0.043 |
Clinical chorioamnionitis | 5 (4.5%) | 3 (20.0%) | 0.078 |
Values are given as mean ± standard deviation or
The proportions of umbilical cord plasma samples with detectable protein levels were 98.4% for M-CSF and 100% for C3a, C5a, IL-6, MMP-9, and endostatin. Of these six proteins measured in the umbilical cord plasma, MMP-9 levels were significantly positively correlated with those of all proteins but M-CSF (
Table
Umbilical cord plasma levels of inflammatory and immune proteins according to newborn hearing screening test results.
Abnormal finding in newborn hearing screening test | |||
---|---|---|---|
Absent ( |
Present ( | ||
Umbilical cord plasma IL-6 (pg/mL) | 11.0 ± 15.1 | 19.0 ± 18.7 | 0.040 |
Umbilical cord plasma C3a ( |
11.8 ± 5.9 | 8.0 ± 5.0 | 0.017 |
Umbilical cord plasma C5a (ng/mL) | 30.3 ± 22.8 | 23.6 ± 10.8 | 0.390 |
Umbilical cord plasma MMP-9 (ng/mL) | 108.0 ± 714.0 | 83.9 ± 71.2 | 0.124 |
Umbilical cord plasma M-CSF (pg/mL) | 715.4 ± 390.8 | 749.7 ± 509.5 | 0.946 |
Umbilical cord plasma endostatin (ng/mL) | 82.9 ± 16.3 | 85.6 ± 17.4 | 0.497 |
Umbilical cord plasma IL-6 > 11 pg/mL | 33 (29.5%) | 8 (53.3%) | 0.063 |
Fetal inflammatory response syndromea | 43 (38.4.0%) | 9 (60.0%) | 0.110 |
Values are given as mean ± standard deviation or
Table
Neonatal characteristics and morbidities according to newborn hearing screening test results.
Abnormal finding on newborn hearing screening test | |||
---|---|---|---|
Absent ( |
Present ( | ||
Gestational age at birth (weeks) | 30.8 ± 2.1 | 30.0 ± 2.9 | 0.448 |
Birth weight (kg) | 1.6 ± 0.4 | 1.5 ± 0.5 | 0.372 |
Male gender | 62 (55.4%) | 10 (66.7%) | 0.406 |
Apgar score < 7 | |||
1 min | 67 (59.8%) | 11 (73.3%) | 0.403 |
5 min | 22 (19.6%) | 5 (33.3%) | 0.310 |
Umbilical artery pH | 7.3 ± 0.06 | 7.3 ± 0.07 | 0.671 |
CRP level > 5 mg/L in immediate postnatal period | 8 (7.1%) | 4 (26.6%) | 0.015 |
WBC count in immediate postnatal period (103 cells/mm3) | 12.9 ± 6.8 | 14.1 ± 14.7 | 0.625 |
Continuous positive airway pressure | 68 (60.7%) | 12 (80%) | 0.168 |
Mechanical ventilation | 47 (42.0%) | 9 (60.0%) | 0.186 |
Use of surfactant | 27 (24.1%) | 7 (46.7%) | 0.116 |
Proven sepsis | 4 (3.6%) | 1 (6.7%) | 0.472 |
Respiratory distress syndrome | 39 (34.8%) | 7 (46.7%) | 0.370 |
Bronchopulmonary dysplasia | 24 (21.4%) | 5 (33.3%) | 0.331 |
Intraventricular hemorrhage, grade 2 or more | 5 (4.5%) | 1 (6.7%) | 0.537 |
Periventricular leukomalacia | 9 (8.0%) | 1 (6.7%) | 1.000 |
Necrotizing enterocolitis | 6 (5.4%) | 0 (0.0%) | 1.000 |
Values are given as mean ± standard deviation or
Multiple logistic regression analyses were performed to further examine the relationship between the various proteins in the umbilical cord plasma and NHS test failure after adjusting for the effects of baseline variables. The following variables were assessed in the multivariate logistic regression analysis as significant predictors in the univariate analyses
Risk factors associated with newborn hearing screening test failure according to logistic regression analyses.
Risk factors | Risk of failure in the newborn hearing screening test | |||
---|---|---|---|---|
Adjusted for umbilical cord plasma C3a | Adjusted for all variables in the model | |||
OR (95% CI) | OR (95% CI) | |||
Umbilical cord plasma IL-6 (pg/mL) | 1.031 (1.000–1.063) | 0.050 | 1.004 (0.960–1.050) | 0.859 |
Funisitis | 3.827 (1.197–12.233) | 0.024 | 2.683 (0.694–10.375) | 0.153 |
Elevated blood CRP levels (>5 mg/L) in immediate postnatal period | 6.515 (1.814–23.398) | 0.019 | 3.503 (0.524–23.404) | 0.196 |
Umbilical cord plasma C3a ( | 0.875 (0.780–0.982) | 0.023 |
OR: odds ratio; CI: confidence interval; IL: interleukin; CRP: C-reactive protein.
Figure
Receiver operating characteristic curves for umbilical cord plasma interleukin-6 (IL-6) “line” and C3a “broken line” for predicting newborn hearing screening test failure (cord plasma IL-6: area under the curve, 0.663; standard error, 0.070; cord plasma C3a: area under the curve, 0.690; standard error, 0.071; no differences (
Our data demonstrate that in preterm neonates, a systemic fetal inflammatory response reflected by umbilical cord plasma IL-6 and immediate postnatal CRP levels may contribute to the risk for NHS test failure, whereas the changes in complement activation fragments initiated
In the literature, elevated IL-6 UCB levels at birth were reportedly associated with an increased risk of neonatal morbidity and mortality, including neonatal sepsis, systemic inflammatory response syndrome, PVL, and NEC [
The complement system plays a central role in innate immunity that provides an effective first line of defense against infection by triggering inflammatory responses [
A body of research has suggested that prenatal infection and resultant fetal inflammatory response contribute to the pathogenesis of severe neonatal neurologic illness, such with white matter injury (WMI) [
Our failure to obtain a statistical association between NHS test failure and MMP-9, C5a, M-CSF, and endostatin levels in the umbilical cord plasma in the present study merits attention. A famous tissue remodeling gene, the
The current study has several limitations. First, this retrospective study was conducted at a single center with a limited number of subjects, limiting our ability to extrapolate our results to the general population. Second, the role of various immune-related proteins in the UCB in the development of SNHL could not be precisely evaluated because of the low prevalence of SNHL. The SNHL incidence in this study (1.5%, 2/127) was in accordance with those of other studies [
In conclusion, in preterm newborns, elevated levels of umbilical cord plasma C3a were independently associated with a reduced risk of NHS test failure, whereas elevated levels of umbilical cord plasma IL-6 and elevated CRP levels in the immediate postnatal period were significantly associated with NHS test failure. However, these measures are not sensitive or specific markers for hearing screen failure (Figure
The data used to support the findings of this study are available from the corresponding author upon request.
The authors declare that there is no conflict of interest.
Ye Ji Shim and Byung Yoon Choi contributed equally to this work.
This research was supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute funded by the Ministry of Health & Welfare, Republic of Korea (Grant no. HI 14C1798).