The effects of standing, lifting and noise exposure on preterm birth, growth restriction, and perinatal death in healthy low-risk working military women

Noise or sound management in the neonatal intensive care unit for preterm or very low birth weight infants

BACKGROUND

Infants in the neonatal intensive care unit (NICU) are subjected to different types of stress, including sounds of high intensity. The sound levels in NICUs often exceed the maximum acceptable level recommended by the American Academy of Pediatrics, which is 45 decibels (dB). Hearing impairment is diagnosed in 2% to 10% of preterm infants compared to only 0.1% of the general paediatric population. Bringing sound levels under 45 dB can be achieved by lowering the sound levels in an entire unit; by treating the infant in a section of a NICU, in a 'private' room, or in incubators in which the sound levels are controlled; or by reducing sound levels at the individual level using earmuffs or earplugs. By lowering sound levels, the resulting stress can be diminished, thereby promoting growth and reducing adverse neonatal outcomes. This review is an update of one originally published in 2015 and first updated in 2020.

OBJECTIVES

To determine the benefits and harms of sound reduction on the growth and long-term neurodevelopmental outcomes of neonates.

SEARCH METHODS

We used standard, extensive Cochrane search methods. On 21 and 22 August 2023, a Cochrane Information Specialist searched CENTRAL, PubMed, Embase, two other databases, two trials registers, and grey literature via Google Scholar and conference abstracts from Pediatric Academic Societies.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) or quasi-RCTs in preterm infants (less than 32 weeks' postmenstrual age (PMA) or less than 1500 g birth weight) cared for in the resuscitation area, during transport, or once admitted to a NICU or stepdown unit. We specified three types of intervention: 1) intervention at the unit level (i.e. the entire neonatal department), 2) at the section or room level, or 3) at the individual level (e.g. hearing protection).

DATA COLLECTION AND ANALYSIS

We used the standardised review methods of Cochrane Neonatal to assess the risk of bias in the studies. We used the risk ratio (RR) and risk difference (RD), with their 95% confidence intervals (CIs), for dichotomous data. We used the mean difference (MD) for continuous data. Our primary outcome was major neurodevelopmental disability. We used GRADE to assess the certainty of the evidence.

MAIN RESULTS

We included one RCT, which enroled 34 newborn infants randomised to the use of silicone earplugs versus no earplugs for hearing protection. It was a single-centre study conducted at the University of Texas Medical School in Houston, Texas, USA. Earplugs were positioned at the time of randomisation and worn continuously until the infants were 35 weeks' postmenstrual age (PMA) or discharged (whichever came first). Newborns in the control group received standard care. The evidence is very uncertain about the effects of silicone earplugs on the following outcomes. • Cerebral palsy (RR 3.00, 95% CI 0.15 to 61.74)and Mental Developmental Index (MDI) (Bayley II) at 18 to 22 months' corrected age (MD 14.00, 95% CI 3.13 to 24.87); no other indicators of major neurodevelopmental disability were reported. • Normal auditory functioning at discharge (RR 1.65, 95% CI 0.93 to 2.94) • All-cause mortality during hospital stay (RR 2.07, 95% CI 0.64 to 6.70; RD 0.20, 95% CI -0.09 to 0.50) • Weight (kg) at 18 to 22 months' corrected age (MD 0.31, 95% CI -1.53 to 2.16) • Height (cm) at 18 to 22 months' corrected age (MD 2.70, 95% CI -3.13 to 8.53) • Days of assisted ventilation (MD -1.44, 95% CI -23.29 to 20.41) • Days of initial hospitalisation (MD 1.36, 95% CI -31.03 to 33.75) For all outcomes, we judged the certainty of evidence as very low. We identified one ongoing RCT that will compare the effects of reduced noise levels and cycled light on visual and neural development in preterm infants.

AUTHORS' CONCLUSIONS

No studies evaluated interventions to reduce sound levels below 45 dB across the whole neonatal unit or in a room within it. We found only one study that evaluated the benefits of sound reduction in the neonatal intensive care unit for hearing protection in preterm infants. The study compared the use of silicone earplugs versus no earplugs in newborns of very low birth weight (less than 1500 g). Considering the very small sample size, imprecise results, and high risk of attrition bias, the evidence based on this research is very uncertain and no conclusions can be drawn. As there is a lack of evidence to inform healthcare or policy decisions, large, well designed, well conducted, and fully reported RCTs that analyse different aspects of noise reduction in NICUs are needed. They should report both short- and long-term outcomes.

Impact of maternal posture on fetal physiology in human pregnancy: a narrative review

In numerous medical conditions, including pregnancy, gravity and posture interact to impact physiology and pathophysiology. Recent investigations, for example, pertaining to maternal sleeping posture during the third trimester and possible impact on fetal growth and stillbirth risk highlight the importance and potential clinical implications of the subject. In this review, we provide an extensive discussion of the impact of maternal posture on fetal physiology from conception to the postpartum period in human pregnancy. We conducted a systematic literature search of the MEDLINE database and identified 242 studies from 1991 through 2021, inclusive, that met our inclusion criteria. Herein, we provide a synthesis of the resulting literature. In the first section of the review, we group the results by the impact of maternal posture at rest on the cervix, uterus, placenta, umbilical cord, amniotic fluid, and fetus. In the second section of the review, we address the impact on fetal-related outcomes of maternal posture during various maternal activities (e.g., sleep, work, exercise), medical procedures (e.g., fertility, imaging, surgery), and labor and birth. We present the published literature, highlight gaps and discrepancies, and suggest future research opportunities and clinical practice changes. In sum, we anticipate that this review will shed light on the impact of maternal posture on fetal physiology in a manner that lends utility to researchers and clinicians who are working to improve maternal, fetal, and child health.

Effect of active-duty military service on neonatal birth outcomes: a systematic review

INTRODUCTION

Increasing numbers of women serve in the armed forces in countries worldwide. Stress experienced during pregnancy is associated with adverse birth outcomes including preterm delivery (PTD) and low birth weight (LBW). Several characteristics of military employment and lifestyle can increase stress acting on active-duty servicewomen (ADSW) and hence may increase the risk of adverse neonatal outcomes. This paper reviews the prevalence of PTD, preterm labour (PTL), LBW and stillbirth in babies born to ADSW in the armed forces.

METHODS

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol. Medline, EMBASE, Web of Science, Global Health and CINAHL Plus databases were searched from inception to July 2021 (November 2023, EMBASE) using subject heading and keyword searches for English language journal articles on babies born to ADSW in any military branch and any country. The Joanna Briggs Institute prevalence critical appraisal tool assessed risk of bias in included papers. Studies were paired with a comparator non-active-duty population to generate a prevalence ratio as the effect measure. A narrative synthesis was conducted.

RESULTS

21 observational studies fulfilled the eligibility criteria. They were all conducted in the US military, involved a total of 650 628 participants, and were published between 1979 and 2023. Their results indicate increased LBW in ADSW compared with non-service women. There was insufficient evidence to conclude or rule out whether ADSW have increased rates of PTD or PTL.

CONCLUSIONS

ADSW may be at increased risk of having an LBW baby. However, caution is needed if seeking to generalise the findings beyond the US context. This review highlights a growing need for female-specific research in other armed forces and, specifically, into reproductive health. Such research is necessary to inform military maternity pathways and policies in ways that safeguard mothers and their babies while enhancing military readiness.

Maternal Occupational Risk Factors and Preterm Birth: A Systematic Review and Meta-Analysis

Objective: This systematic review and meta-analysis aimed to summarize the evidence on the relationship between physical occupational risks (high physical workload, long working hours, shift work, whole-body vibrations, prolonged standing, and heavy lifting) and preterm birth. Methods: A systematic review and meta-analysis was conducted across six databases to investigate the relationship between physical occupational risks and preterm birth. Result: A comprehensive analysis of 37 studies with varying sample sizes found moderate evidence of positive associations between high physical workload, long working hours, shift work, whole-body vibration, and preterm birth. Meta-analysis showed a 44% higher risk (OR 1.44, 95% CI 1.25-1.66) for preterm birth with long working hours and a 63% higher risk (OR 1.63, 95% CI 1.03-2.58) with shift work. Conclusion: Pregnant women in physically demanding jobs, those working long hours or on shifts, and those exposed to whole-body vibration have an increased risk of preterm birth. Employers should establish supportive workplaces, policymakers implement protective measures, healthcare providers conduct screenings, and pregnant women must stay informed and mitigate these job-related risks. Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/], Identifier [CRD42022357045].

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.

Music Therapy Intervention in an Open Bay Neonatal Intensive Care Unit Room Is Associated with Less Noise and Higher Signal to Noise Ratios: A Case-Control Study

BACKGROUND

Noise reduction in the Neonatal Intensive Care Unit (NICU) is important for neurodevelopment, but the impact of music therapy on noise is not yet known.

OBJECTIVE

To investigate the effect of music therapy (MT) on noise levels, and whether individual MT (IMT) or environmental MT (EMT) increases meaningful signal-to-noise ratios (SNR).

STUDY DESIGN

This case-control study was conducted in a level III NICU. Noise levels were recorded simultaneously from two open bay rooms, with a maximum of 10 infants in each room: one with MT and the other without. MT sessions were carried out for approximately 45 min with either IMT or EMT, implemented according to the Rhythm Breath and Lullaby principles. Noise production data were recorded for 4 h on 26 occasions of EMT and IMT, and analyzed using R version 4.0.2 software.

RESULTS

Overall average equivalent continuous noise levels (Leq) were lower in the room with MT as compared to the room without MT (53.1 (3.6) vs. 61.4 (4.7) dBA, p = 0.02, d = 2.1 (CI, 0.82, 3.42). IMT was associated with lower overall Leq levels as compared to EMT (51.2 vs. 56.5 dBA, p = 0.04, d = 1.6 (CI, 0.53, 1.97). The lowest sound levels with MT occurred approximately 60 min after the MT started (46 ± 3.9 dBA), with a gradual increase during the remaining recording time, but still significantly lower compared to the room without MT. The SNR was higher (18.1 vs. 10.3 dBA, p = 0.01, d = 2.8 (CI, 1.3, 3.86)) in the room with MT than in the room without MT.

CONCLUSION

Integrating MT modalities such as IMT and EMT in an open bay NICU room helps reduce noise. Both MT modalities resulted in higher SNR compared to the control room, which may indicate that they are meaningful for the neurodevelopment of preterm infants.

A Scoping Review of Pregnancy, Childbirth, and the Postpartum Period in Active Duty U.S. Military Women

PURPOSE

Women in the U.S. military encounter unique challenges during the perinatal period that are driven by military requirements for mission readiness. The purpose of this scoping review was to systematically examine the extent, range, and nature of the literature on pregnancy, childbirth, and the postpartum period of active duty military women. A secondary aim was to identify leverage points for changes to improve perinatal health of servicewomen.

METHODS

We used a PRISMA-ScR protocol to guide this scoping review of research and non-research articles germane to the perinatal health of servicewomen. In the protocol, we identified the rationale, objectives, eligibility criteria, search strategy, sources of evidence, and data charting processes for the review. We used the social ecological model for military women's health framework to guide the synthesis of results.

FINDINGS

Eighty-four articles on the topics of pregnancy, childbirth, and the postpartum period of servicewomen published from 2000 to 2018 were identified. The articles were mainly research studies (n = 76), of which 49 had observational designs. Leverage points to promote workplace safety and support of pregnant women, perinatal screening, recognition of pregnancy and postpartum depression, and maintaining physical fitness during pregnancy and the postpartum period were identified in multiple levels of the social ecological model for military women's health.

CONCLUSIONS

Literature published from 2000 to 2018 is broad in scope, yet generally lacks a robust body of evidence on any one topic. Implementing strategies and military policies that are directed at the identified leverage points could enhance the health of childbearing servicewomen.

First trimester employment, working conditions and preterm birth: a prospective population-based cohort study

Objectives

To explore the association between working conditions during first trimester and total preterm birth (PTB), and subtypes: spontaneous PTB and iatrogenic PTB, additionally to explore the role of hypertension.

Methods

Pregnant women from the Amsterdam Born Children and their Development study, filled out a questionnaire between January 2003 and March 2004, two weeks after first prenatal screening (singleton liveborn, n=7561). Working conditions were working hours/week, standing/walking hours/week, physical work load and job strain.

Results

Prolonged standing/walking during first trimester was associated with an increased risk for total PTB (OR=1.5; 95% CI 1.0–2.3, after adjustments). Other working conditions were not related to total PTB. The separation into spontaneous and iatrogenic PTB revealed that standing/walking was associated with iatrogenic PTB only (OR=2.09; 95% CI 1.00–4.97). The highest risk was found for the combination of a long workweek with high physical work load (OR=3.42; 95% CI 1.04–8.21). Hypertension did not mediate these associations; however, stratified analysis revealed that high physical work load was only related to iatrogenic PTB when pregnancy-induced hypertension was present (OR=6.44; 95% CI 1.21–29.76).

Conclusion

This study provides evidence that high physically demanding work is associated with an increased risk for iatrogenic PTB and not with spontaneous PTB. Pregnancy-induced hypertension may play a role: when present, high physical work load leads to a more severe outcome.

Pregnancy vs. paycheck: a qualitative study of patient's experience with employment during pregnancy at high risk for preterm birth

Background

Pregnant women with a history of preterm birth are at risk for recurrence, often requiring frequent prenatal visits for close monitoring and/or preventive therapies. Employment demands can limit uptake and adherence to recommended monitoring and preterm birth prevention therapies.

Method

We conducted a qualitative descriptive study using in-depth interviews (IDIs) of pregnant women with a history of preterm birth. IDIs were conducted by trained qualitative interviewers following a semi-structured interview guide focused on uncovering barriers and facilitators to initiation of prenatal care, including relevant employment experiences, and soliciting potential interventions to improve prompt prenatal care initiation. The IDIs were analyzed via applied thematic analysis.

Results

We described the interview findings that address women’s employment experiences. The current analysis includes 27 women who are majority self-described as non-Hispanic Black (74%) and publically insured (70%). Participants were employed in a range of professions; food services, childcare and retail were the most common occupations. Participants described multiple ways that being pregnant impacted their earning potential, ranging from voluntary work-hour reduction, involuntary duty hour reductions by employers, truncated promotions, and termination of employment. Participants also shared varying experiences with workplace accommodations to their work environment and job duties based on their pregnancy. Some of these accommodations were initiated by a collaborative employee/employer discussion, others were initiated by the employer’s perception of safe working conditions in pregnancy, and some accommodations were based on medical recommendations. Participants described supportive and unsupportive employer reactions to requests for accommodations.

Conclusions

Our findings provide novel insights into women’s experiences balancing a pregnancy at increased risk for preterm birth with employment obligations. While many women reported positive experiences, the most striking insights came from women who described negative situations that ranged from challenging to potentially unlawful. Many of the findings suggest profound misunderstandings likely exist at the patient, employer and clinical provider level about the laws surrounding employment in pregnancy, safe employment responsibilities during pregnancy, and the range of creative accommodations that often allow for continued workplace productivity even during high risk pregnancy.

Occupational lifting and adverse pregnancy outcome: a systematic review and meta-analysis

This systematic review was conducted to help clarify the effect of lifting at work on pregnancy outcome, by focusing on specific exposure categories. A search in Medline and Embase identified 51 articles reporting association of spontaneous abortion (SA), preterm delivery (PTD) or small-for-gestational-age (SGA) infant with exposure to occupational lifting. A global validity score was assigned to each study and six potential sources of bias were considered in sensitivity analyses. For each exposure–outcome combination, a summary risk estimate (RE) was obtained from all studies and from a subset of studies with high validity score, this latter summary RE was selected as a final result. Statistical heterogeneity was measured with I2 and Q tests and the possibility of a publication bias was also assessed. For each meta-analysis, the strength of evidence was established from explicit criteria. Heavy (or ≥10 kg) loads often (or ≥10x/day) lifted were associated with increased risks of SA (summary RE=1.31, 95% CI 1.17 to 1.47) and PTD (summary RE=1.24, 95% CI 1.07 to 1.43), with good strength of evidence. No association was identified with SGA, nor with lower exposure levels and SA or PTD. These results are reassuring for lower levels of exposure; however, observed associations can guide health professionals’ recommendations aimed at the prevention of SA and PTD for pregnant women who frequently lift (or ≥10x/day) heavy (or ≥10 kg) loads at work.

Résumé

The impact of occupational activities during pregnancy on pregnancy outcomes: a systematic review and metaanalysis

OBJECTIVE

Data: An increasing number of studies suggest that exposure to physically demanding work during pregnancy could be associated with increased risks of adverse pregnancy outcomes, but the results remain conflicted and inconclusive. The purpose of this study was to examine the influence of occupational activities during pregnancy on maternal and fetal health outcomes.

STUDY

Studies of all designs (except case studies and reviews) that contained information on the relevant population (women who engaged in paid work during pregnancy), occupational exposures (heavy lifting, prolonged standing, prolonged walking, prolonged bending, and heavy physical workload), comparator (no exposure to the listed physical work demands), and outcomes (preterm birth, low birthweight, small for gestational age, miscarriage, gestational hypertension, preeclampsia, gestational diabetes mellitus, stillbirth, and intrauterine growth restriction) were included.

STUDY APPRAISAL AND SYNTHESIS METHODS

Five electronic databases and 3 gray literature sources were searched up to March 15, 2019.

RESULTS

Eighty observational studies (N=853,149) were included. Low-to-very low certainty evidence revealed that lifting objects ≥11 kg was associated with an increased odds ratio of miscarriage (odds ratio, 1.31; 95% confidence interval, 1.08-1.58; I²=79%), and preeclampsia (odds ratio, 1.35; 95% confidence interval, 1.07-1.71; I²=0%). Lifting objects for a combined weight of ≥100 kg per day was associated with an increased odds of preterm delivery (odds ratio, 1.31; 95% confidence interval, 1.11-1.56; I²=0%) and having a low birthweight neonate (odds ratio, 2.08; 95% confidence interval, 1.06-4.11; I²=73%). Prolonged standing was associated with increased odds of preterm delivery (odds ratio, 1.11; 95% confidence interval, 1.02-1.22; I²=30%) and having a small-for-gestational-age neonate (odds ratio, 1.17; 95% confidence interval, 1.01-1.35; I²=41%). A heavy physical workload was associated with increased odds of preterm delivery (odds ratio, 1.23; 95% confidence interval, 1.07-1.41; I²=32%) and having a low birthweight neonate (odds ratio, 1.79; 95% confidence interval, 1.11-2.87; I²=87%). All other associations were not statistically significant. Dose-response analysis showed women stand for >2.5 hours per day (vs no standing) had a 10% increase in the odds of having a preterm delivery.

CONCLUSION

Physically demanding work during pregnancy is associated with an increased risk of adverse pregnancy outcomes.

Sound reduction management in the neonatal intensive care unit for preterm or very low birth weight infants

BACKGROUND

Infants in the neonatal intensive care unit (NICU) are subjected to stress, including sound of high intensity. The sound environment in the NICU is louder than most home or office environments and contains disturbing noises of short duration and at irregular intervals. There are competing auditory signals that frequently challenge preterm infants, staff and parents. The sound levels in NICUs often exceed the maximum acceptable level of 45 decibels (dB), recommended by the American Academy of Pediatrics. Hearing impairment is diagnosed in 2% to 10% of preterm infants versus 0.1% of the general paediatric population. Noise may cause apnoea, hypoxaemia, alternation in oxygen saturation, and increased oxygen consumption secondary to elevated heart and respiratory rates and may, therefore, decrease the amount of calories available for growth. Elevated levels of speech are needed to overcome the noisy environment in the NICU, thereby increasing the negative impacts on staff, newborns, and their families. High noise levels are associated with an increased rate of errors and accidents, leading to decreased performance among staff. The aim of interventions included in this review is to reduce sound levels to 45 dB or less. This can be achieved by lowering the sound levels in an entire unit, treating the infant in a section of a NICU, in a 'private' room, or in incubators in which the sound levels are controlled, or reducing the sound levels that reaches the individual infant by using earmuffs or earplugs. By lowering the sound levels that reach the neonate, the resulting stress on the cardiovascular, respiratory, neurological, and endocrine systems can be diminished, thereby promoting growth and reducing adverse neonatal outcomes.

OBJECTIVES

Primary objective To determine the effects of sound reduction on growth and long-term neurodevelopmental outcomes of neonates. Secondary objectives 1. To evaluate the effects of sound reduction on short-term medical outcomes (bronchopulmonary dysplasia, intraventricular haemorrhage, periventricular leukomalacia, retinopathy of prematurity). 2. To evaluate the effects of sound reduction on sleep patterns at three months of age. 3. To evaluate the effects of sound reduction on staff performance. 4. To evaluate the effects of sound reduction in the neonatal intensive care unit (NICU) on parents' satisfaction with the care.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE, EMBASE, CINAHL, abstracts from scientific meetings, clinical trials registries (clinicaltrials.gov; controlled-trials.com; and who.int/ictrp), Pediatric Academic Societies Annual meetings 2000 to 2014 (Abstracts2ViewTM), reference lists of identified trials, and reviews to November 2014.

SELECTION CRITERIA

Preterm infants (< 32 weeks' postmenstrual age (PMA) or < 1500 g birth weight) cared for in the resuscitation area, during transport, or once admitted to a NICU or a stepdown unit.

DATA COLLECTION AND ANALYSIS

We performed data collection and analyses according to the Cochrane Neonatal Review Group.

MAIN RESULTS

One small, high quality study assessing the effects of silicone earplugs versus no earplugs qualified for inclusion. The original inclusion criteria in our protocol stipulated an age of < 48 hours at the time of initiating sound reduction. We made a deviation from our protocol and included this study in which some infants would have been > 48 hours old. There was no significant difference in weight at 34 weeks postmenstrual age (PMA): mean difference (MD) 111 g (95% confidence interval (CI) -151 to 374 g) (n = 23). There was no significant difference in weight at 18 to 22 months corrected age between the groups: MD 0.31 kg, 95% CI -1.53 to 2.16 kg (n = 14). There was a significant difference in Mental Developmental Index (Bayley II) favouring the silicone earplugs group at 18 to 22 months corrected age: MD 14.00, 95% CI 3.13 to 24.87 (n = 12), but not for Psychomotor Development Index (Bayley II) at 18 to 22 months corrected age: MD -2.16, 95% CI -18.44 to 14.12 (n =12).

AUTHORS' CONCLUSIONS

To date, only 34 infants have been enrolled in a randomised controlled trial (RCT) testing the effectiveness of reducing sound levels that reach the infants' ears in the NICU. Based on the small sample size of this single trial, we cannot make any recommendations for clinical practice. Larger, well designed, conducted and reported trials are needed.

History of the establishment of the Preterm Birth international collaborative (PREBIC)

INTRODUCTION

The primary aim of PREBIC is to assess the underlying mechanisms and developing strategies for preterm birth (PTB) prevention.

MATERIALS AND METHODS

We used concept mapping and logic models to track goals. This paper reviews our progress over 13 years using working group activities, research developments, guest speakers, and publications.

RESULTS

Using interactions between genetics, environment, and behaviors we identified complex interactions between biological systems. PREBIC determined that epidemiology and biomarkers should be an initial focus. In 2005, we initiated presentations by young investigators, yearly satellite meetings, working groups including nutrition and inflammation, assessment of clinical trials, and accepted an invitation by the WHO to begin yearly meetings in Geneva.

DISCUSSION

PREBIC used epidemiology to identify PTB factors and complex pathways. Candidate genes are associated with the environment, behavior (stress), obesity, inflammation and insulin resistance. Epigenetic changes and production of proteins can be used as biomarkers to define risk. Subsequently, we found risk factors for PTB that were also associated with the risk of cardiovascular disease (CVD) of the mother. Tanz et al. (2017) found that a history of PTB is independently predictive of CVD later in life and suggested that a modest proportion of PTB-CVD association was accounted by CVD risk factors, many of which have been identified in this paper.

CONCLUSION

Our findings support a relationship between genes, environment, behaviors and risk of CVD in women. The next several years must assess which factors are modifiable early in life and before pregnancy to prevent PTB.

Full-time exposure to occupational noise during pregnancy was associated with reduced birth weight in a nationwide cohort study of Swedish women

Noise is a common exposure in the occupational work environment. Earlier studies of occupational noise and pregnancy outcome are few and show mixed results. To investigate if objectively assessed exposure to occupational noise during pregnancy is associated with reduced intrauterine growth and/or preterm birth a nationwide cohort study of 857,010 single births was initiated. Individual information on occupation and risk factors was retrieved from prenatal care interviews at pregnancy week 10. Occupational noise was classified into three exposure categories <75, 75-85, >85 dBA by a job exposure matrix. Odds ratios were adjusted for BMI, smoking, parity, education, physically strenuous work and low job control. Exposure to high (>85 dBA) levels of occupational noise throughout the pregnancy (full time workers) was associated with an increased risk of the child being born small for gestational age, OR 1.44 (95% CI 1.01 to 2.03) compared to noise exposure <75 dBA. A similar increase was seen for low birth weight OR 1.36 (95% CI 1.03 to 1.80) for high levels of noise. No clear association was seen for preterm birth. No consistent effects on birth outcome was observed in women who had worked part-time or were on leave of absence >21 days (median). In summary, full-time exposure to high levels of noise during pregnancy was associated with a slightly reduced fetal growth but not with preterm birth. The effect of intermediate occupational noise exposure (75-85 dBA) showed a small, but statistically increased risk for all studied birth outcomes. The study strengthens the evidence that pregnant women should not be long-term exposed to high levels >85 dBA of occupational noise during pregnancy. Intermediate exposure should be studied further.

Traffic noise exposure in relation to adverse birth outcomes and body mass between birth and adolescence

BACKGROUND

There is growing evidence that traffic noise exposure is associated with adiposity among adults but data in children are limited.

OBJECTIVE

This longitudinal study examined whether pre- and postnatal noise exposure is associated with body mass index (BMI) between birth and adolescence or with adverse birth outcomes.

METHODS

The study was conducted using data from the BAMSE birth cohort, which included 4089 children born in Stockholm County, Sweden. Data on BMI from birth to adolescence were collected via questionnaires, clinical examinations and health care records. A national register provided information on birth outcomes. Road traffic noise levels at the most exposed façade were estimated for all residences of the children during follow-up, as well as of their mothers during pregnancy, and time-weighted average exposure was calculated for different time windows. Maternal occupational noise exposure was obtained from a job-exposure-matrix. Logistic- and quantile regression models were used to estimate associations between noise exposure and health outcomes.

RESULTS

We found residential road traffic noise exposure to be associated with increases in BMI from school age to adolescence, but not at earlier ages. In the age groups 8-11 years and 12-16 years the BMI increments were 0.11 kg/m² per 10 dB L_den (95% CI 0.08-0.13) and 0.20 kg/m² per 10 dB L_den (95% CI 0.17-0.22), respectively. Maternal noise exposure during pregnancy was generally unrelated to adverse birth outcomes and BMI from birth to adolescence in the children, however, traffic noise exposure was associated with a decreased risk of preterm birth CONCLUSION: Residential road traffic noise exposure was associated with BMI increases from school age to adolescence, but not at earlier ages. Maternal occupational noise exposure or exposure from road traffic during pregnancy were not consistently related to birth outcomes or BMI from birth to adolescence.

A detailed description of the short-term musculoskeletal and cognitive effects of prolonged standing for office computer work

Due to concerns about excessive sedentary exposure for office workers, alternate work positions such as standing are being trialled. However, prolonged standing may have health and productivity impacts, which this study assessed. Twenty adult participants undertook two hours of laboratory-based standing computer work to investigate changes in discomfort and cognitive function, along with muscle fatigue, movement, lower limb swelling and mental state. Over time, discomfort increased in all body areas (total body IRR [95% confidence interval]: 1.47[1.36-1.59]). Sustained attention reaction time (β = 18.25[8.00-28.51]) deteriorated, while creative problem solving improved (β = 0.89[0.29-1.49]). There was no change in erector spinae, rectus femoris, biceps femoris or tibialis anterior muscle fatigue; low back angle changed towards less  lordosis, pelvis movement increased, lower limb swelling increased and mental state decreased. Body discomfort was positively correlated with mental state. The observed changes suggest replacing office work sitting with standing should be done with caution. Practitioner Summary: Standing is being used to replace sitting by office workers; however, there are health risks associated with prolonged standing. In a laboratory study involving 2 h prolonged standing discomfort increased (all body areas), reaction time and mental state deteriorated while creative problem-solving improved. Prolonged standing should be undertaken with caution.

Biomechanical and organisational stressors and associations with employment withdrawal among pregnant workers: evidence and implications

The distribution of exposure to biomechanical and organisational job stressors (BOJS) and associations with employment withdrawal (antenatal leave, unemployment) was examined in a case-control study of 1114 pregnant workers in California. We performed descriptive and multivariate logistic and multinomial regression analyses. At pregnancy onset, 57% were exposed to one or more biomechanical stressors, including frequent bending, heavy lifting and prolonged standing. One-third were simultaneously exposed to BOJS. Exposure to biomechanical stressors declined as pregnancy progressed and cessation often (41%) coincided with employment withdrawal (antenatal leave and unemployment). In multivariate modelling, whether we adjusted for or considered organisational stressors as coincident exposures, results showed that pregnant workers exposed to biomechanical stressors had increased employment withdrawal compared to the unexposed. Work schedule accommodations moderate this association. Paid antenatal leave, available to few US women, was an important strategy for mitigating exposure to BOJS. Implications for science and policy are discussed. Practitioner Summary: This case-control study showed that exposure to biomechanical stressors decline throughout pregnancy. Antenatal leave was an important strategy used for mitigating exposure among sampled California women with access to paid benefits. Employment withdrawal among workers exposed to BJOS may be reduced by proactive administrative and engineering efforts applied early in pregnancy.

Impact of air pollution and temperature on adverse birth outcomes: Madrid, 2001-2009

BACKGROUND/OBJECTIVES

Low birth weight (<2500 g) (LBW), premature birth (<37 weeks of gestation) (PB), and late foetal death (<24 h of life) (LFD) are causes of perinatal morbi-mortality, with short- and long-term social and economic health impacts. This study sought to identify gestational windows of susceptibility during pregnancy and to analyse and quantify the impact of different air pollutants, noise and temperature on the adverse birth outcomes.

METHODS

Time-series study to assess the impact of mean daily PM_2.5, NO₂ and O₃ (μg/m³), mean daily diurnal (Leqd) and nocturnal (Leqn) noise levels (dB(A)), maximum and minimum daily temperatures (°C) on the number of births with LBW, PB or LFD in Madrid across the period 2001-2009. We controlled for linear trend, seasonality and autoregression. Poisson regression models were fitted for quantification of the results. The final models were expressed as relative risk (RR) and population attributable risk (PAR).

RESULTS

Leqd was observed to have the following impacts in LBW: at onset of gestation, in the second trimester and in the week of birth itself. NO₂ had an impact in the second trimester. In the case of PB, the following: Leqd in the second trimester, Leqn in the week before birth and PM_2.5 in the second trimester. In the case of LFD, impacts were observed for both PM_2.5 in the third trimester, and minimum temperature. O₃ proved significant in the first trimester for LBW and PB, and in the second trimester for LFD.

CONCLUSIONS

Pollutants concentrations, noise and temperature influenced the weekly average of new-borns with LBW, PB and LFD in Madrid. Special note should be taken of the effect of diurnal noise on LBW across the entire pregnancy. The exposure of pregnant population to the environmental factors analysed should therefore be controlled with a view to reducing perinatal morbi-mortality.

Sound reduction management in the neonatal intensive care unit for preterm or very low birth weight infants

BACKGROUND

Infants in the neonatal intensive care unit (NICU) are subjected to stress, including sound of high intensity. The sound environment in the NICU is louder than most home or office environments and contains disturbing noises of short duration and at irregular intervals. There are competing auditory signals that frequently challenge preterm infants, staff and parents. The sound levels in NICUs often exceed the maximum acceptable level of 45 decibels (dB), recommended by the American Academy of Pediatrics. Hearing impairment is diagnosed in 2% to 10% of preterm infants versus 0.1% of the general paediatric population. Noise may cause apnoea, hypoxaemia, alternation in oxygen saturation, and increased oxygen consumption secondary to elevated heart and respiratory rates and may, therefore, decrease the amount of calories available for growth. Elevated levels of speech are needed to overcome the noisy environment in the NICU, thereby increasing the negative impacts on staff, newborns, and their families. High noise levels are associated with an increased rate of errors and accidents, leading to decreased performance among staff. The aim of interventions included in this review is to reduce sound levels to 45 dB or less. This can be achieved by lowering the sound levels in an entire unit, treating the infant in a section of a NICU, in a 'private' room, or in incubators in which the sound levels are controlled, or reducing the sound levels that reaches the individual infant by using earmuffs or earplugs. By lowering the sound levels that reach the neonate, the resulting stress on the cardiovascular, respiratory, neurological, and endocrine systems can be diminished, thereby promoting growth and reducing adverse neonatal outcomes.

OBJECTIVES

Primary objectiveTo determine the effects of sound reduction on growth and long-term neurodevelopmental outcomes of neonates. Secondary objectives1. To evaluate the effects of sound reduction on short-term medical outcomes (bronchopulmonary dysplasia, intraventricular haemorrhage, periventricular leukomalacia, retinopathy of prematurity).2. To evaluate the effects of sound reduction on sleep patterns at three months of age.3. To evaluate the effects of sound reduction on staff performance.4. To evaluate the effects of sound reduction in the neonatal intensive care unit (NICU) on parents' satisfaction with the care.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library), MEDLINE, EMBASE, CINAHL, abstracts from scientific meetings, clinical trials registries (clinicaltrials.gov; controlled-trials.com; and who.int/ictrp), Pediatric Academic Societies Annual meetings 2000 to 2014 (Abstracts2View(TM)), reference lists of identified trials, and reviews to November 2014.

SELECTION CRITERIA

Preterm infants (< 32 weeks' postmenstrual age (PMA) or < 1500 g birth weight) cared for in the resuscitation area, during transport, or once admitted to a NICU or a stepdown unit.

DATA COLLECTION AND ANALYSIS

We performed data collection and analyses according to the Cochrane Neonatal Review Group.

MAIN RESULTS

One small, high quality study assessing the effects of silicone earplugs versus no earplugs qualified for inclusion. The original inclusion criteria in our protocol stipulated an age of < 48 hours at the time of initiating sound reduction. We made a deviation from our protocol and included this study in which some infants would have been > 48 hours old. There was no significant difference in weight at 34 weeks postmenstrual age (PMA): mean difference (MD) 111 g (95% confidence interval (CI) -151 to 374 g) (n = 23). There was no significant difference in weight at 18 to 22 months corrected age between the groups: MD 0.31 kg, 95% CI -1.53 to 2.16 kg (n = 14). There was a significant difference in Mental Developmental Index (Bayley II) favouring the silicone earplugs group at 18 to 22 months corrected age: MD 14.00, 95% CI 3.13 to 24.87 (n = 12), but not for Psychomotor Development Index (Bayley II) at 18 to 22 months corrected age: MD -2.16, 95% CI -18.44 to 14.12 (n =12).

AUTHORS' CONCLUSIONS

To date, only 34 infants have been enrolled in a randomised controlled trial (RCT) testing the effectiveness of reducing sound levels that reach the infants' ears in the NICU. Based on the small sample size of this single trial, we cannot make any recommendations for clinical practice. Larger, well designed, conducted and reported trials are needed.

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.

Physically demanding work and preterm delivery: a systematic review and meta-analysis

OBJECTIVE

Physically demanding work may increase the risk of preterm delivery (PTD), defined as delivery before 37 weeks. We assessed the available evidence.

METHODS

A systematic search in Medline, Embase and Nioshtic for the period 1990 to June 2012 for observational and intervention studies on physically demanding work (prolonged standing, heavy lifting, physical exertion, occupational fatigue and demanding posture) and PTD. Selected studies were assessed for their risk of bias and pooled using a random effects model. Results of case-control and cohort studies were reported separately in subgroups.

RESULTS

We found 10 studies with low risk of bias and seven studies with moderate risk of bias. Standing and walking at work during pregnancy for more than 3 h per day was associated with an increased risk for PTD [OR 1.3 (95% CI 1.1-1.6)], just as lifting and carrying >5 kg [OR 1.3 (95% CI 1.05-1.6)] or lifting and carrying in the third trimester of the pregnancy [OR 1.3 (95% CI 1.01-1.8)]. Jobs that required physical effort or physical exertion were associated with an increased risk of PTD [OR 1.4 (95% CI 1.19-1.66)]. Working during pregnancy in jobs with a combination of two or more physical tasks, physical effort or occupational fatigue was also associated with an increased risk of PTD [OR 1.5 (95% CI 1.1-2.0)].

CONCLUSIONS

Physically demanding work during pregnancy is associated with an increased risk of PTD, especially in jobs with a combination of tasks with physical effort. In general, only small to moderate elevations of risks were found.

Clinical guidelines for occupational lifting in pregnancy: evidence summary and provisional recommendations

Empirically based lifting criteria established by the National Institute for Occupational Safety and Health (NIOSH) to reduce the risk of overexertion injuries in the general US working population were evaluated for application to pregnant workers. This report proposes criteria to guide decisions by medical providers about permissible weights for lifting tasks performed at work over the course of an uncomplicated pregnancy. Our evaluation included an extensive review of the literature linking occupational lifting to maternal and fetal health. Although it has been 29 years since the American Medical Association's Council on Scientific Affairs published its report on the Effects of Pregnancy on Work Performance, these guidelines continue to influence clinical decisions and workplace policies. Provisional clinical guidelines derived from the NIOSH lifting criteria that account for recent evidence for maternal and fetal health are presented and aim to improve the standard of care for pregnant workers.

Work activities and risk of prematurity, low birth weight and pre-eclampsia: an updated review with meta-analysis

OBJECTIVES

We assessed the evidence relating preterm delivery (PTD), low birth weight, small for gestational age (SGA), pre-eclampsia and gestational hypertension to five occupational exposures (working hours, shift work, lifting, standing and physical workload). We conducted a systematic search in Medline and Embase (1966 to 2011), updating a previous search with a further 6 years of observations.

METHODS

As before, combinations of keywords and medical subject headings were used. Each relevant paper was assessed for completeness of reporting and potential for important bias or confounding, and its effect estimates abstracted. Where similar definitions of exposure and outcome existed we calculated pooled estimates of relative risk (RR) in meta-analysis.

RESULTS

Analysis was based on 86 reports (32 cohort investigations, 57 with usable data on PTD, 54 on birth weight and 11 on pre-eclampsia/gestational hypertension); 33 reports were new to this review. For PTD, findings across a substantial evidence base were generally consistent, effectively ruling out large effects (eg, RR>1.2). Larger and higher quality studies were less positive, while meta-estimates of risk were smaller than in previous analyses and best estimates pointed to modest or null effects (RR 1.04 to 1.18). For SGA, the position was similar but meta-estimates were even closer to the null (eight of nine RRs ≤ 1.07). For pre-eclampsia/gestational hypertension the evidence base remains insufficient.

CONCLUSIONS

The balance of evidence is against large effects for the associations investigated. As the evidence base has grown, estimates of risk in relation to these outcomes have become smaller.

A literature review of air medical work hazards and pregnancy

An increased percentage of miscarriages among coworkers at one air medical transport company in 2008 prompted a literature review of selected hazards relevant to the profession of rotor wing air medical flight crew. Because of a lack of known research specific to this population, relevant studies from 1990 to 2008 were chosen to investigate pregnancy risks associated with exposure to vibration, jet fuel, noise, altitude, and fatigue in other occupations. Findings were summarized and recommendations made for future research.

A pregnancy wellness guide to enhance care through self-assessment, personal reflection, and self-referral

OBJECTIVE

To develop a tool and evaluate its content validity and utility. The tool was designed to be used by women to assess lifestyle and psychosocial factors that could impact their pregnancies and unborn babies. It also provided resources for self-help.

DESIGN

Methodological study in 4 phases.

SETTING

Alberta Health Services, Calgary area and community.

PARTICIPANTS

Thirty-five experts and 375 pregnant women.

METHODS

Pregnant women and new mothers participated in focus groups to establish content validity; prenatal class attendees completed the self-assessment and a questionnaire, and women from the community completed a questionnaire on the instrument's utility.

RESULTS

Responses from experts and participants in all 4 phases led to changes in the content, wording, and format of the tool. Survey responses indicated that it contained useful information that prompted a number of women to make positive changes during their pregnancies.

CONCLUSION

The Pregnancy Wellness Guide is a simple tool that can help pregnant women assess their knowledge and health behaviors and self-refer to helpful resources. It will be widely distributed throughout the health region in the urban and rural Calgary area, and its use is anticipated to result in better health outcomes in pregnancy.

Evaluation of preterm births and birth defects in liveborn infants of US military women who received smallpox vaccine

BACKGROUND

Women serving in the US military have some unique occupational exposures, including exposure to vaccinations that are rarely required in civilian professions. When vaccinations are inadvertently given during pregnancy, such exposures raise special concerns. These analyses address health outcomes, particularly preterm births and birth defects, among infants who appear to have been exposed to maternal smallpox vaccination in pregnancy.

METHODS

This retrospective cohort study included 31,420 infants born to active-duty military women during 2003-2004. We used Department of Defense databases to define maternal vaccination and infant health outcomes. Multivariable regression models were developed to describe associations between maternal smallpox vaccination and preterm births and birth defects in liveborn infants.

RESULTS

There were 7,735 infants identified as born to women ever vaccinated against smallpox, and 672 infants born to women vaccinated in the first trimester of pregnancy. In multivariable modeling, maternal smallpox vaccination in pregnancy was not associated with preterm or extreme preterm delivery. Maternal smallpox vaccination in the first trimester of pregnancy was not significantly associated with overall birth defects (OR 1.40; 95% CI: 0.94, 2.07), or any of seven specific defects individually modeled.

CONCLUSIONS

Results may be reassuring that smallpox vaccine, when inadvertently administered to pregnant women, is not associated with preterm delivery or birth defects in liveborn infants.

Risk of prematurity, low birthweight and pre-eclampsia in relation to working hours and physical activities: a systematic review

BACKGROUND

Occupational activities are suspected of having an adverse impact on outcomes of pregnancy.

AIM

To assess the evidence relating three major adverse outcomes (preterm delivery, low birthweight (LBW) and pre-eclampsia/gestational hypertension) to five common occupational exposures (prolonged working hours, shift work, lifting, standing and heavy physical workload).

METHODS

A systematic search of Medline and Embase (1966-December 2005) using combinations of keywords and medical subject heading terms was conducted. For each relevant paper, standard details were abstracted that were then used to summarise the design features of studies, to rate their methodological quality (completeness of reporting and potential for important bias or confounding) and to provide estimates of effect. For studies with similar definitions of exposure and outcome, pooled estimates of relative risk (RR) in meta-analysis were calculated.

RESULTS

53 reports were identified-35 on preterm delivery, 34 on birth weight and 9 on pre-eclampsia or gestational hypertension. These included 21 cohort investigations. For pre-term delivery, extensive evidence relating to each of the exposures of interest was found. Findings were generally consistent and tended to rule out a more than moderate effect size (RR >1.4). The larger and most complete studies were less positive, and pooled estimates of risk pointed to only modest or null effects. For small-for-gestational age, the position was similar, but the evidence base was more limited. For pre-eclampsia and gestational hypertension, it was too small to allow firm conclusions.

CONCLUSIONS

The balance of evidence is not sufficiently compelling to justify mandatory restrictions on any of the activities considered in this review. However, given some uncertainties in the evidence base and the apparent absence of important beneficial effects, it may be prudent to advise against long working hours, prolonged standing and heavy physical work, particularly late in pregnancy. Our review identifies several priorities for future investigation.