Noise exposure during pregnancy and selected structural malformations in infants

Occupational and environmental noise exposure during pregnancy and rare health outcomes of offspring: a scoping review focusing on congenital anomalies and perinatal mortality

As environmental and occupational noise can be health hazards, recent studies have investigated the effects of noise exposure during pregnancy. Despite biological plausibility and animal studies supporting an association, studies focusing on congenital anomalies and perinatal mortality as outcomes of noise exposure are still scarce. We performed a scoping review to collect, summarise, and discuss the existing scientific research about the relationships between noise exposure during pregnancy and congenital anomalies and/or perinatal mortality. We searched electronic databases for papers published between 1970 and March 2021. We included 16 studies (seven on congenital anomalies, three on perinatal mortality, and two on both congenital anomalies and perinatal mortality). We assessed four studies on congenital hearing dysfunction as the definition of congenital anomalies includes functional anomalies. We found few studies on this topic and no studies on the combined effects of occupational and environmental noise exposures. Evidence suggests a small increase in the risk of congenital anomalies in relation to occupational and to a lesser extent environmental noise exposure. In addition, few studies investigated perinatal mortality and the ones that did, used different outcome definitions, so no conclusions could be made. However, a recent big cross-sectional study demonstrated an association between road traffic noise and stillbirth. A few studies suggest a possible association between congenital hearing dysfunction and occupational noise exposure during pregnancy. Future studies with larger samples, better exposure assessments, and better statistical modelling strategies are needed to investigate these relationships further.

Exposure to air pollution and noise from road traffic and risk of congenital anomalies in the Danish National Birth Cohort

BACKGROUND

Ambient air pollution has been associated with certain congenital anomalies, but few studies rely on assessment of fine-scale variation in air quality and associations with noise from road traffic are unexplored.

METHODS

Among 84,218 liveborn singletons (1997-2002) from the Danish National Birth Cohort with complete covariate data and residential address history from conception until birth, we identified major congenital anomalies in 4018 children. Nitrogen dioxide (NO₂) and noise from road traffic (L_den) burden during fetal life was modeled. Outcome and covariate data were derived from registries, hospital records and questionnaires. Odds ratios (ORs) for eleven major anomaly groups associated with road traffic pollution during first trimester were estimated using logistic regression with generalized estimating equation (GEE) approach.

RESULTS

Most of the associations tested did not suggest increased risks. A 10-µg/m³ increase in NO₂ exposure during first trimester was associated with an adjusted ORs of 1.22 (95% confidence interval: 0.98-1.52) for ear, face and neck anomalies; 1.14 0.98-1.33) for urinary anomalies. A 10-dB increase in road traffic noise was also associated with these subgroups of anomalies as well as with an increased OR for orofacial cleft anomalies (1.17, 0.94-1.47). Inverse associations for several both air pollution and noise were observed for atrial septal defects (0.85, 0.68-1.04 and 0.81, 0.65-0.99, respectively).

CONCLUSIONS

Residential road traffic exposure to noise or air pollution during pregnancy did not seem to pose a risk for development of congenital anomalies.

Reproductive outcomes associated with noise exposure - a systematic review of the literature

Introduction: High noise exposure during critical periods in gestation is a potential stressor that may result in increased risk of implantation failure, dysregulation of placentation or decrease of uterine blood flow. This paper systematically reviews published evidence on associations between reproductive outcomes and occupational and environmental noise exposure. Methods: The Web of Science, PubMed and Embase electronic databases were searched for papers published between 1970 to June 2014 and via colleagues. We included 14 epidemiological studies related to occupational noise exposure and nine epidemiological studies related to environmental noise exposure. There was some evidence for associations between occupational noise exposure and low birthweight, preterm birth and small for gestational age, either independently or together with other occupational risk factors. Five of six epidemiologic studies, including the two largest studies, found significant associations between lower birthweight and higher noise exposure. There were few studies on other outcomes and study design issues may have led to bias in assessments in some studies. Conclusions: There is evidence for associations between noise exposure and adverse reproductive outcomes from animal studies. Few studies in have been conducted in humans but there is some suggestive evidence of adverse associations with environmental noise from both occupational and epidemiological studies, especially for low birthweight.

Impact of environmental noise on growth and neuropsychological development of newborn rats

We aimed to investigate the effects of environmental noise exposure on the growth and neuropsychological development in neonatal rats. Twenty-four postnatal 7-day-old Sprague-Dawley rats were randomly assigned into control, high-noise and reduced noise groups. The rats in the high-noise group were exposed to 90 dB white noise, and those in the control group were grown under standard condition, while those in the reduced noise group were exposed to standard condition with sound-absorbing cotton. Ten, 15, and 20 days post noise exposure, both the body weight and length of the rats in high-noise group were lower than those in the control and reduced noise groups, respectively. The secretion of growth hormone was significantly decreased in the rats exposed to high noise environment, compared to those exposed to standard condition and reduced noise. More interestingly, the swimming distance was apparently increased and the swimming speed was significantly decreased in high-noise group compared with those in control and reduced noise groups. Importantly, the mRNA and protein levels of SYP in the rats hippocampus were significantly decreased in high-noise group compare with those in control and reduced noise groups. Similarly, the positive expression of SYP in the CA1 region of hippocampus was also significantly decreased in the high noise group rats. In conclusion, our results demonstrated that high noise exposure could decrease the production of growth hormone and SYP in neonatal rats, which may retard the growth of weight and length and the capability of learning and memory.

Safe sound exposure in the fetus and preterm infant

Exposure to sound can have beneficial and harmful effects on the developing fetus and preterm infant. Although recommendations for safe exposure to sound have existed for more than three decades, reports indicate that these recommendations are not being followed. Recommendations are made to promote attention to the problem of unsafe exposure to sound in early development, and a multidisciplinary team, including representatives from disciplines beyond medicine and nursing, must redress safe exposure.

Etiology of hearing loss in children. Nongenetic causes

Every child with a hearing loss should have an evaluation to determine the cause of hearing loss. This article focuses on the nongenetic origins of hearing loss, the most frequent of which is the neonatal intensive care unit experience, followed by meningitis, cytomegalovirus, and other infections. Preventable causes such as exposure to ototoxic medications and noise are also discussed in this article.

Teratogenic effects of noise and cadmium in mice: does noise have teratogenic potential?

The teratogenicity of combined exposure to noise and cadmium was studied in mice. ICR mice were exposed to a wide octave-band of noise at 100 dB(C) for 6 h on d 7 of pregnancy in one of two ways: continuous exposure or intermittent (15 min on/15 min off). Cadmium sulfate at 1 or 2 mg/kg was intraperitoneally injected on d 7 of pregnancy. Four groups were exposed to both cadmium and noise. On d 18 of pregnancy, fetuses were examined for external and skeletal malformations. Another experiment was performed with two other patterns of noise exposure: continuous exposure for 3 h, and intermittent exposure (5 min on/5 min off) for 6 h on d 7 of pregnancy. In the groups exposed to continuous noise for 6 h, total percentages of malformed fetuses were significantly higher than that in the control group, but there were no significant increases of total percentages of fetal malformations in the combined treatment groups in comparison with the groups given the same dose of cadmium alone. The percentages of skeletally malformed fetuses in groups exposed to 6 h of continuous noise were significantly higher than in groups that received saline or the same dose of cadmium. There were no significant differences in the total percentages of malformed fetuses between the control group and the groups exposed to a total of 3 h of noise, whether continuously or intermittently. Although combined treatment with cadmium and noise resulted in an increase of total percentages of malformed fetuses compared to the same dose of cadmium alone, the interactions between cadmium and noise showed no synergistic effect on teratogenicity. The magnitude of teratogenicity due to noise is much weaker than that of cadmium, and is therefore easily masked by that of cadmium in statistical tests of the significance of differences.

Occupational risk factors for congenital heart disease

To investigate possible associations between cardiovascular malformations and maternal occupational exposure to various factors during the first trimester of pregnancy, 406 cases and 756 controls were studied retrospectively. The cases were taken from all infants diagnosed with cardiovascular malformations born in Finland during 1982 and 1983. The controls were randomly selected from all normal births in the country during the same period. All mothers were interviewed approximately 3 months after delivery by a midwife, using a structured questionnaire. Maternal overall exposure to chemicals at work was more prevalent among the case group (35.8%) than the control group (26.2%, P less than 0.01). Among the specific chemical groups, maternal exposure to dyes, lacquers, or paints was significantly associated with the risk of congenital heart disease. Exposure to organic solvents during the first trimester seemed to increase to risk of ventricular septal defect (P less than 0.05). Work at video display terminals was slightly more prevalent among the case group (6.3%) than among the control group (5.0%). The mothers' education level, regular exposure to passive smoking at work, or temperature at the workplace were not risk factors for congenital heart disease in the offspring, neither was maternal exposure to microwave ovens, disinfectants, pesticides, or anesthetic gases. It is concluded that many maternal exposures at work seem not to have a teratogenic effect on the fetal heart, although the limited power of this investigation needs to be borne in mind.