Maternal smoking during pregnancy: impact on otoacoustic emissions in neonates

The Association between Prenatal Nicotine Exposure and Offspring's Hearing Impairment

OBJECTIVES

The objective of this study is to evaluate whether there is an association between in-utero exposure to nicotine and subsequent hearing dysfunction.

MATERIALS AND METHODS

Secondary analysis of a multicenter randomized trial to prevent congenital cytomegalovirus (CMV) infection among gravidas with primary CMV infection was conducted. Monthly intravenous immunoglobulin hyperimmune globulin therapy did not influence the rate of congenital CMV. Dyads with missing urine, fetal or neonatal demise, infants diagnosed with a major congenital anomaly, congenital CMV infection, or with evidence of middle ear dysfunction were excluded. The primary outcome was neonatal hearing impairment in one or more ears defined as abnormal distortion product otoacoustic emissions (DPOAEs; 1 to 8 kHz) that were measured within 42 days of birth. DPOAEs were interpreted using optimized frequency-specific level criteria. Cotinine was measured via enzyme-linked immunosorbent assay kits in maternal urine collected at enrollment and in the third trimester (mean gestational age 16.0 and 36.7 weeks, respectively). Blinded personnel ran samples in duplicates. Maternal urine cotinine >5 ng/mL at either time point was defined as in-utero exposure to nicotine. Multivariable logistic regression included variables associated with the primary outcome and with the exposure (p < 0.05) in univariate analysis.

RESULTS

Of 399 enrolled patients in the original trial, 150 were included in this analysis, of whom 46 (31%) were exposed to nicotine. The primary outcome occurred in 18 (12%) newborns and was higher in nicotine-exposed infants compared with those nonexposed (15.2 vs. 10.6%, odds ratio [OR] 1.52, 95% confidence interval [CI] 0.55-4.20), but the difference was not significantly different (adjusted odds ratio [aOR] = 1.0, 95% CI 0.30-3.31). This association was similar when exposure was stratified as heavy (>100 ng/mL, aOR 0.72, 95% CI 0.15-3.51) or mild (5-100 ng/mL, aOR 1.28, 95% CI 0.33-4.95). There was no association between nicotine exposure and frequency-specific DPOAE amplitude.

CONCLUSION

In a cohort of parturients with primary CMV infection, nicotine exposure was not associated with offspring hearing dysfunction assessed with DPOAEs.

KEY POINTS

· Nicotine exposure was quantified from maternal urine.. · Nicotine exposure was identified in 30% of the cohort.. · Exposure was not associated with offspring hearing dysfunction..

Cry features of healthy neonates who passed their newborn hearing screening vs. those who did not

OBJECTIVES

Temporal and fundamental frequency (fo) variations in infant cries provide critical insights into the maturity of vocal control and hearing performances. Earlier research has examined the use of vocalisation properties (in addition to hearing tests) to identify infants at risk of hearing impairment. The aim of this study was to determine whether such an approach could be suitable for neonates.

METHODS

To investigate this, we recruited 74 healthy neonates within their first week of life as our participants, assigning them to either a group that passed the ABR-based NHS (PG, N = 36) or a group that did not, but were diagnosed as normally hearing in follow-up check at 3 months of life, a so-called false-positive group (NPG, N = 36). Spontaneously uttered cries (N = 2330) were recorded and analysed quantitatively. The duration, minimum, maximum and mean fo, as well as two variability measures (fo range, fo sigma), were calculated for each cry utterance, averaged for individual neonates, and compared between the groups.

RESULTS

A multiple analysis of variance (MANOVA) revealed no significant effects. This confirms that cry features reflecting vocal control do not differ between healthy neonates with normal hearing, irrespective of the outcome of their initial NHS.

CONCLUSIONS

Healthy neonates who do not pass the NHS but are normal hearing in the follow-up (false positive cases) have the same cry properties as those with normal hearing who do. This is an essential prerequisite to justify the research strategy of incorporating vocal analysis into NHS to complement ABR measures in identifying hearing-impaired newborns.

Otoacoustic emissions in neonates exposed to smoke during pregnancy

Introduction

The toxic substances present in cigarette smoke can damage cochlea hair cells. This effect has been investigated by measuring otoacoustic emissions.

Objective

To investigate the impact of stimuli on otoacoustic emissions, comparing neonates with and without exposure to cigarette smoke during pregnancy.

Methods

Transient-evoked otoacoustic emissions, evoked by a click stimulus, and distortion product otoacoustic emissions, evoked by two tones tests were conducted in both ears, using an Interacoustic TITAN device. The study included 105 neonates divided into two groups: a study group, comprising 47 neonates exposed to smoke during pregnancy; and a control group comprized of 58 neonates who were not exposed. All participants had normal neonatal hearing screening.

Results

No statistical differences in distortion product otoacoustic emissions response levels were found between the groups. In the transient-evoked otoacoustic emissions tests lower response levels were observed in the study group than the control group in frequency band analysis of the right ear, with statistically significant differences in signals and signal-noise ratio (except at 1 kHz).

Conclusion

The impact of smoking exposure could be analyzed through transient-evoked otoacoustic emissions in neonates. The group effect of smoke exposure during pregnancy was evidenced by a reduction in transient-evoked otoacoustic emissions levels. This same effect was not observed for the analyses performed on distortion product otoacoustic emissions levels.

Exposure to tobacco smoke prenatally and during infancy and risk of hearing impairment among children in Japan: A retrospective cohort study

BACKGROUND

Previous studies of the association between tobacco smoke and hearing loss in children are limited, involve small samples and are cross-sectional. We investigated the association of maternal smoking during pregnancy and exposure to tobacco smoke at age 4 months with hearing impairment at age 3 years in children.

METHODS

This population-based retrospective cohort study included 50 734 children born between 2004 and 2010 in Kobe City, Japan. Smoking during pregnancy and exposure to tobacco smoke at 4 months was measured using parent-reported questionnaires. Hearing impairment was determined by the whispered voice test.

RESULTS

Of the included children, 3.8% were exposed to smoking only during pregnancy; 3.9% were exposed only to second-hand smoke at 4 months; and 0.9% were exposed to tobacco smoke during pregnancy and at 4 months. The prevalence of hearing impairment at age 3 years was 4.6%. Compared with children not exposed to tobacco smoke prenatally and at 4 months, the risk of hearing impairment was elevated in children exposed to only maternal past smoking during pregnancy (RR 1.26, 95% CI 1.13, 1.40), only second-hand smoke at 4 months (RR 1.30, 95% CI 1.07, 1.56), only smoking during pregnancy (RR 1.68, 95% CI 1.42, 2.00) and smoking during pregnancy and second-hand smoke at 4 months (RR 2.35, 95% CI 1.79, 3.10).

CONCLUSIONS

Exposure to tobacco smoke prenatally and postnatally was associated with hearing impairment in children. A prevention of smoking before and during pregnancy and exposure to second-hand smoke postnatally may reduce hearing impairment risk in children.

Substance use in pregnancy: The medical challenge

Substance use contributes significantly to the global burden of disease. Growing numbers of women use nicotine, alcohol, and illicit substances. Women are the most vulnerable to problematic substance use in their reproductive years. The first 1000 days of life, starting at conception, have been established as a critical window of time for long-term health and development. Substance use in pregnancy is associated with negative pregnancy and child health outcomes. The impact of antenatal substance use on these outcomes needs to be considered within a challenging and complex context. This review provides an overview of the current literature on the impact of substances on pregnancy and child outcomes as well as the evidence and guidelines on screening and interventions for women using substances during pregnancy.

Impact of Nicotine Exposure on Hair Cell Toxicity and Embryotoxicity During Zebrafish Development

Objectives

Nicotine has various adverse effects including negative impacts associated with maternal exposure. In the current study, we examined nicotine-induced damage of hair cells and embryotoxicity during zebrafish development.

Methods

Zebrafish embryos were exposed to nicotine at several concentrations (5, 10, 20, and 40 μM) and embryotoxicity were evaluated at 72 hours, including hatching rate, mortality, teratogenicity rate, and heart rate. Hair cells within the supraorbital (SO1 and SO2), otic (O1), and occipital (OC1) neuromasts were identified at 120 hours. Apoptosis and mitochondrial damage of hair cells were analyzed using TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling) and DASPEI (2-[4-(dimethylamino)styryl]-N-ethylpyridinium iodide) assays, respectively, and changes of ultrastructure were observed by scanning electron microscopy.

Results

The control group without nicotine appeared normal with overall mortality and teratogenicity rate <5%. The hatching rate and mortality rate was not significantly different according to nicotine concentration (n=400 each). The abnormal morphology rate (n=400) increased and heart rate (n=150) decreased with increasing nicotine concentration (P<0.05). Nicotine-induced hair cell damage significantly increased as nicotine concentration increased. A significantly greater number of TUNEL-positive cells (P<0.01) and markedly smaller DASPEI area (P<0.01) were shown as nicotine concentration increased.

Conclusion

The current results suggest that nicotine induces dose-dependent hair cell toxicity in embryos by promoting apoptosis and mitochondrial and structural damage.

Newborn hearing screening failure and maternal factors during pregnancy

OBJECTIVE

Temporary conductive hearing loss due to amniotic fluid accumulation in the middle ear cavity may lead to failure (false positive) in newborn hearing screening tests. The aim of this study was to identify whether amniotic fluid index has association with failure of the initial newborn otoacoustic emission (OAE) screening test.

METHODS

A cohort study in a tertiary hospital center (Royal Victoria Hospital, Montréal) was constructed from 70 newborns that failed the OAE test, but passed a subsequent auditory brainstem response (ABR) test, and 75 randomly selected newborns that passed initial otoacoustic emission testing. Maternal (including the amniotic fluid index in the third trimester) and newborn clinical data were extracted from medical records. Statistical association models were built to determine variables that influenced hearing screen passage or failure.

RESULTS

The two arms of the cohort had no significant differences in maternal or child clinical indices, including in amniotic fluid index. Calculated as individual odds ratios, maternal tobacco [95% CI of odds ratio: 0.04, 0.59, p = 0.0078], and drug use [95% CI of odds ratio: 0.0065, 0.72, p = 0.058] [borderline significance] were associated with failing the otoacoustic emission testing.

CONCLUSIONS

Amniotic fluid index was not found to be associated with failure of otoacoustic emission screening in newborns. However, our study unveiled an interesting unexpected association of OAE failure with maternal smoking and/or drug use. This finding can help alleviate some of the time, cost and parental anxiety related to failed OAE screening. In selected cases of maternal smoking or drug use we might want to replace or add OAE to the ABR test in newborn hearing screening protocols, that don't perform both tests before discharge.

Effect of passive smoking on auditory temporal resolution in children

OBJECTIVE

To determine the effect of passive smoking on auditory temporal resolution in primary school children, based on the hypothesis that individuals who are exposed to smoking exhibit impaired performance.

DESIGN

Auditory temporal resolution was evaluated using the Gaps In Noise (GIN) test. Exposure to passive smoking was assessed by measuring nicotine metabolite (cotinine) excreted in the first urine of the day.

STUDY SAMPLE

The study included 90 children with mean age of 10.2 ± 0.1 years old from a public school in São Paulo. Participants were divided into two groups: a study group, comprising 45 children exposed to passive smoking (cotinine > 5 ng/mL); and a control group, constituting 45 children who were not exposed to passive smoking. All participants had normal audiometry and immittance test results.

RESULTS

Statistically significant differences (p < 0.005) in performance on the GIN test were found between the two groups, with mean thresholds of 5.3 ms and 68.9% correct responses in the study group versus 4.6 ms and 74.0% in the control group.

CONCLUSION

The children exposed to passive smoking had poorer performance both in terms of thresholds and correct responses percentage on auditory temporal resolution assessment.

Acoustic absorbance measurements in neonates exposed to smoking during pregnancy

OBJECTIVE

To analyze acoustic absorbance using wideband tympanometry in neonates exposed to passive smoking during pregnancy.

METHOD

A study comprising 54 neonates in the control group (CG - unexposed) and 19 in the study group (SG - exposed) was carried out. Subjects were submitted to the wideband tympanometry test and subsequent analysis of absorbance of 17 frequencies.

RESULT

Low frequencies had a lower level of absorbance compared to high frequencies for both ambient and peak pressures, with no difference between the groups.

CONCLUSION

No effect of passive smoking on acoustic absorbance measurements in neonates was observed.

Secondhand Smoke is Associated with Hearing Threshold Shifts in Obese Adults

Hearing loss resulted from multiple intrinsic and extrinsic factors. Secondhand smoke (SHS) and obesity had been reported to be related to hearing loss. This study explored the possible associations of SHS and obesity with the hearing threshold. The relations between SHS and the hearing threshold in subjects from three different body mass index classes were analyzed. Our study included data from 1,961 subjects aged 20–69 years that were obtained from the National Health and Nutrition Examination Survey for the years 1999–2004. After adjusting for potential confounding factors, the subjects with the higher tertiles of serum cotinine levels tended to have higher hearing thresholds than those with the lowest tertile of serum cotinine levels (for both trends, p < 0.05). Notably, the obese subjects with the higher tertiles of serum cotinine levels had significantly higher hearing thresholds for high frequencies and low frequencies than those with the lowest tertile of serum cotinine levels (for both trends, p < 0.05). Our study showed a significant positive association between SHS exposure and hearing thresholds in the adult population, especially in obese individuals. Based on our findings, avoiding exposure to SHS, especially in obese adults, may decrease the risk of hearing loss.

Otoacoustic Emissions in Smoking and Nonsmoking Young Adults

Objectives

The present study investigates the usefulness of transiently evoked otoacoustic emissions (TEOAEs) and distortion product OAEs (DPOAEs) in detecting small changes in the hearing of young smoking adults.

Methods

Otoacoustic emissions were acquired from the ears of 48 young adults (age, 20 to 27 years). The dataset was divided into two groups, smoking (24 persons/48 ears) and nonsmoking (24 persons/48 ears). The level of smoking was relatively small in comparison to previous studies, an average of 3.8 years and 8.7 cigarettes per day. In each ear three OAE measurements were made: TEOAEs, DPOAEs, and spontaneous OAEs (SOAEs). Pure tone audiometry and tympanometry were also conducted. Audiometric thresholds did not differ significantly between the datasets. Half-octave-band values of OAE signal to noise ratios and response levels were used to assess statistical differences.

Results

Averaged data initially revealed that differences between the two study groups occurred only for TEOAEs at 1 kHz. However when the datasets were divided into ears with and without SOAEs more differences became apparent, both for TEOAEs and DPOAEs. In ears that exhibited SOAEs, both smokers and nonsmokers, there were no statistically significant differences between evoked OAEs; however in all ears without SOAEs, evoked OAEs were higher in the ears of nonsmokers, by as much as 5 dB. These differences were most prominent in the 1-2 kHz range.

Conclusion

A general decrease in OAE levels was found in the group of smokers. However, in ears which exhibited SOAEs, there was no difference between the evoked OAEs of smokers and nonsmokers. We conclude that smoking had not yet measurably affected the ears of those with acute hearing (i.e., those who exhibit SOAEs). However, in ears without SOAEs, smokers exhibited smaller evoked OAE amplitudes than nonsmokers, even though their audiometric thresholds were within the norm.

Personally Modifiable Risk Factors Associated with Pediatric Hearing Loss: A Systematic Review

BACKGROUND

Pediatric hearing loss is an increasingly recognized problem with significant implications. Increasing our quantitative understanding of potentially modifiable environmental risk factors for hearing loss may form the foundation for prevention and screening programs.

OBJECTIVE

To determine whether specific threshold exposure levels of personally modifiable risk factors for hearing loss have been defined, with the overarching goal of providing actionable guidance for the prevention of pediatric hearing loss.

DATA SOURCES

A systematic review was performed. Computerized searches of PubMed, EMBASE, and the Cochrane Library were completed and supplemented with manual searches.

REVIEW METHODS

Inclusion/exclusion criteria were designed to determine specific threshold values of personally modifiable risk factors on hearing loss in the pediatric population. Searches and data extraction were performed by independent reviewers.

RESULTS

There were 38 criterion-meeting studies, including a total of 50,651 subjects. Threshold noise exposures significantly associated with hearing loss in youth included: (1) more than 4 hours per week or more than 5 years of personal headphone usage, (2) more than 4 visits per month to a discotheque, and (3) working on a mechanized farm. Quantified tobacco levels of concern included any level of in utero smoke exposure as well as secondhand exposure sufficient to elevate serum cotinine.

CONCLUSIONS

Specific thresholds analyses are limited. Future studies would ideally focus on stratifying risk according to clearly defined levels of exposure, in order to provide actionable guidance for children and families.

Tobacco smoke exposure during childhood: effect on cochlear physiology

The rate of smoking in Brazil is about 18.8%. Exposure to environmental tobacco smoke is one of the major factors predisposing children to several hazardous health problems. The objective of the present research was to analyze the effect of tobacco smoke exposure during childhood on cochlear physiology by measuring the transient evoked otoacoustic emissions (TEOAE) response levels. Cotinine, the main metabolite of nicotine, was measured in 145 students’ (8–10 years old) urine. Sixty students indicated tobacco smoke exposure (TSE) (cotinine urine levels ≥ 5.0 ng/mL) and 85 did not. The evaluation of TEOAE of TSE students showed lower response levels, mainly on frequencies of 2.8 kHz on the right and left ears and 2.0 kHz on left ear and lower signal noise response levels, mainly on the 1.0 kHz and 1.4 kHz frequencies, when compared to controls that were not exposed to tobacco. The mean hearing loss in tobacco smoke exposure children was 2.1 dB SPL. These results have important implications on the damage to the cochlear structures and indicate a possible loss in hearing and hearing ability development.

[Perinatal factors affecting the detection of otoacoustic emissions in vaginally delivered, healthy newborns, during the first 48 hours of life]

INTRODUCTION AND OBJECTIVES

Most hospitals perform neonatal hearing screening because it is a very useful procedure. Otoacoustic emissions are an ideal technique for this screening. We analyse the possible influence on screening results of some perinatal factors.

MATERIALS AND METHODS

We collected retrospective data from 8,239 healthy newborns delivered vaginally at the maternity ward of our hospital. We compared multiple perinatal factors vs the results of otoacoustic emissions performed within the first 48 h of life, before discharge.

RESULTS

A total of 6.4% of newborns had an abnormal response and failed the screening. Univariate and multivariate analysis showed a significant (P<.0001) positive relationship between breastfeeding and normal otoacoustic emissions (OR: 0.65). Another, less significant factor was female gender. The remaining variables, including origin, education or employment status of the mother, maternal smoking, dystocic delivery, presentation, need for resuscitation, preterm labour (34-36 weeks), weight, length and frequent maternal pathology, such as streptococcus detection, hypothyroidism, hypertension or diabetes, were not significant.

CONCLUSIONS

Breastfeeding was the most important factor related to a normal response in otoacoustic emissions. It may improve final results and reduce the number of neonates who need to be rescheduled for a repeated test, as well as the associated anxiety and the possibility of losing patients during follow-up. These are major problems in neonatal hearing screening.

Exposure of pregnant women to waterpipe and cigarette smoke

INTRODUCTION

Throughout the Eastern Mediterranean region, tobacco is used primarily in 2 forms: cigarette smoking and waterpipe smoking. Despite the fact that tobacco use is considered as a global public health threat, waterpipe smoking is reported to be growing in popularity, particularly among women. The objectives of this study are to determine the prevalence and patterns of cigarette, waterpipe, and passive smoking among pregnant women in Jordan, and to assess their perception of harmful effects of cigarette and waterpipe smoking.

METHODS

A total of 500 pregnant women were randomly recruited from maternity clinics in North and Middle of Jordan and surveyed regarding exposure to waterpipe tobacco and cigarette smoking.

RESULTS

The results showed that 7.9% of women were current cigarette smokers and 8.7% were current waterpipe smokers. About 82.4% of all women reported that they are exposed to cigarette smoke and 32.8% reported that they are exposed to waterpipe smoke. The most common place where women are exposed to cigarette and waterpipe smoke was their house (50.4% and 48.7%, respectively) followed by public places (31.4% and 21.4%, respectively). In addition, the husband was the main source for exposure to cigarette and waterpipe smoke (48.5% and 42.7%, respectively). Approximately, 74% of women believed that cigarette smoking is addictive, whereas only 55.1% reported that waterpipe smoking leads to addiction.

CONCLUSIONS

Exposure of pregnant women to tobacco smoke is a public health problem in Jordan that requires immediate action.

Otoacoustic emissions in neonates measured with different acquisition protocols

OBJECTIVE

The purpose of the study was to investigate the properties of neonatal transiently evoked otoacoustic emissions (TEOAEs) recorded with three most popular stimulation protocols. Differences between the recorded TEOAEs with and without spontaneous otoacoustic emissions (SOAEs), were also assessed. In addition two more issues were addressed: (i) the effect of windowing on the TEOAE responses; and (ii) the contribution of the TEOAE segment from 12.5 to 20 ms to the overall TEOAE response.

METHODS

TEOAEs and SOAEs were recorded from 50 normal hearing neonates using linear, non-linear, QuickScreen and standard synchronized SOAE stimulation protocols. Global and half-octave-band values of TEOAE reproducibility and response level were used to assess statistical differences in the recorded responses. Furthermore protocol differences were evaluated in different recording windows from 2.5 to 12.5 and 12 to 20 ms.

RESULTS

Data from the linear protocol presented TEOAE parameters with the highest values. The differences between recordings with longer and shorter acquisition windows were especially apparent in 1-1.4 kHz frequency range. Furthermore the data have shown that the low frequency TEOAE components are a significant part of the TEOAE response, especially in ears without SOAEs.

CONCLUSIONS

The results suggest that TEOAE protocols using short recording windows (i.e. QuickScreen) can be used only for a fast detection of a valid TEOAE. For more sophisticated clinical analyses the standard 20 ms TEOAE recording window is more appropriate. The presence of SOAEs significantly influences TEOAEs. Ears with SOAEs presented higher values of TEOAE parameters especially in the 2-4 kHz range. On the other hand, in the ears without SOAEs low frequency components contribute more to the signal.