A prospective study of work-related physical exertion and spontaneous abortion

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.

Pregnancy, obstetrical and neonatal outcomes in women exposed to physician-related occupational hazards: a scoping review

OBJECTIVE

Evidence is needed to guide organisational decision making about workplace accommodations for pregnant physicians. Our objective was to characterise the strengths and limitations of current research examining the association between physician-related occupational hazards with pregnancy, obstetrical and neonatal outcomes.

DESIGN

Scoping review.

DATA SOURCES

MEDLINE/PubMed, EMBASE, CINAHL/ EBSCO, SciVerse Scopus and Web of Science/Knowledge were searched from inception to 2 April 2020. A grey literature search was performed on 5 April 2020. The references of all included articles were hand searched for additional citations.

ELIGIBILITY CRITERIA

English language citations that studied employed pregnant people and any 'physician-related occupational hazards', meaning any relevant physical, infectious, chemical or psychological hazard, were included. Outcomes included any pregnancy, obstetrical or neonatal complication.

DATA EXTRACTION AND SYNTHESIS

Physician-related occupational hazards included physician work, healthcare work, long work hours, 'demanding' work, disordered sleep, night shifts and exposure to radiation, chemotherapy, anaesthetic gases or infectious disease. Data were extracted independently in duplicate and reconciled through discussion.

RESULTS

Of the 316 included citations, 189 were original research studies. Most were retrospective, observational and included women in any occupation rather than healthcare workers. Methods for exposure and outcome ascertainment varied across studies and most studies had a high risk of bias in data ascertainment. Most exposures and outcomes were defined categorically and results from different studies could not be combined in a meta-analysis due to heterogeneity in how these categories were defined. Overall, some data suggested that healthcare workers may have an increased risk of miscarriage compared with other employed women. Long work hours may be associated with miscarriage and preterm birth.

CONCLUSIONS

There are important limitations in the current evidence examining physician-related occupational hazards and adverse pregnancy, obstetrical and neonatal outcomes. It is not clear how the medical workplace should be accommodated to improve outcomes for pregnant physicians. High-quality studies are needed and likely feasible.

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.

The impact of occupational shift work and working hours during pregnancy on health outcomes: a systematic review and meta-analysis

BACKGROUD

An increasing number of original studies suggest that exposure to shift work and long working hours during pregnancy could be associated with the risk of adverse pregnancy outcomes, but the results remain conflicting and inconclusive.

OBJECTIVE

To examine the influences of shift work and longer working hours during pregnancy on maternal and fetal health outcomes.

DATA SOURCES

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

METHODS OF STUDY SELECTION

Studies of all designs (except case studies and reviews) were included, which contained information on the relevant population (women who engaged in paid work during pregnancy); exposure (rotating shift work [shifts change according to a set schedule], fixed night shift [typical working period is between 11:00 pm and 11:00 am] or longer working hours [>40 hours per week]);comparator (fixed day shift [typical working period is between 8:00 am and 6:00 pm] or standard working hours [≤40 hours per week]); and outcomes (preterm delivery, low birthweight [birthweight <2500 g], small for gestational age, miscarriage, gestational hypertension, preeclampsia, intrauterine growth restriction, stillbirth, and gestational diabetes mellitus).

TABULATION, INTEGRATION, AND RESULTS

From 3305 unique citations, 62 observational studies (196,989 women) were included. "Low" to "very low" certainty evidence from these studies revealed that working rotating shifts was associated with an increased odds of preterm delivery (odds ratio, 1.13; 95% confidence interval, 1.00-1.28, I² = 31%), an infant small for gestational age (odds ratio, 1.18, 95% confidence interval, 1.01-1.38, I² = 0%), preeclampsia (odds ratio, 1.75, 95% confidence interval, 1.01-3.01, I² = 75%), and gestational hypertension (odds ratio, 1.19, 95% confidence interval, 1.10-1.29, I² = 0%), compared to those who worked a fixed day shift. Working fixed night shifts was associated with an increased odds of preterm delivery (odds ratio, 1.21; 95% confidence interval, 1.03-1.42; I² = 36%) and miscarriage (odds ratio, 1.23; 95% confidence interval, 1.03-1.47; I² = 37%). Compared with standard hours, working longer hours was associated with an increased odds of miscarriage (odds ratio, 1.38; 95% confidence interval, 1.08-1.77; I² = 73%), preterm delivery (odds ratio, 1.21; 95% confidence interval, 1.11-1.33; I² = 30%), an infant of low birthweight (odds ratio, 1.43; 95% confidence interval, 1.11-1.84; I² = 0%), or an infant small for gestational age (odds ratio, 1.16, 95% confidence interval, 1.00-1.36, I² = 57%). Dose-response analysis showed that women working more than 55.5 hours (vs 40 hours) per week had a 10% increase in the odds of having a preterm delivery.

CONCLUSION

Pregnant women who work rotating shifts, fixed night shifts, or longer hours have an increased risk of adverse pregnancy outcomes.

Spontaneous and repeat spontaneous abortion risk in relation to occupational characteristics among working Korean women: a cross-sectional analysis of nationally representative data from Korea

Background

The association between spontaneous abortion (SA) and occupational characteristics among working women is not well-studied. This study aimed to assess the risk of SA and occupational factors such as occupational classification, working hours, and work schedules among working Korean women aged > 19 years.

Methods

In this cross-sectional study, 4078 working women were identified from among 25,534 workers in the Korea National Health and Nutrition Examination Surveys V (2010–2012) database, to obtain data on SA history and the number of SAs. Odds ratios (ORs) and 95% confidence intervals (CIs) for SA were calculated using multiple logistic regression models after adjusting for age, education, household income, cigarette smoking, alcohol consumption, and obesity status. The weighted prevalence for the number of SAs was calculated according to occupational characteristics to demonstrate the SA status among working Korean women.

Results

SA occurrence was reported in 5.7% of the study participants. The ORs (95% CIs) for SA were significantly higher in pink-, green-, and blue-collared workers than in white-collared workers. Regarding weekly working hours, compared with ≤50 h spent working, the ORs (95% CIs) for 51–60, 61–70, and > 70 h per week were 1.26 (0.87–1.84), 1.63 (1.04–2.56), and 1.73 (1.10–2.70), respectively. A significantly higher weighted prevalence of repeat SAs was observed in pink- and green-collared workers and in those who worked long hours.

Conclusion

We found a significant association between SA, repeat SA, and occupational characteristics among working Korean women.

Night work and miscarriage: a Danish nationwide register-based cohort study

Objective

Observational studies indicate an association between working nights and miscarriage, but inaccurate exposure assessment precludes causal inference. Using payroll data with exact and prospective measurement of night work, the objective was to investigate whether working night shifts during pregnancy increases the risk of miscarriage.

Methods

A cohort of 22 744 pregnant women was identified by linking the Danish Working Hour Database (DWHD), which holds payroll data on all Danish public hospital employees, with Danish national registers on births and admissions to hospitals (miscarriage). The risk of miscarriage during pregnancy weeks 4–22 according to measures of night work was analysed using Cox regression with time-varying exposure adjusted for a fixed set of potential confounders.

Results

In total 377 896 pregnancy weeks (average 19.7) were available for follow-up. Women who had two or more night shifts the previous week had an increased risk of miscarriage after pregnancy week 8 (HR 1.32 (95% CI 1.07 to 1.62) compared with women, who did not work night shifts. The cumulated number of night shifts during pregnancy weeks 3–21 increased the risk of miscarriages in a dose-dependent pattern.

Conclusions

The study corroborates earlier findings that night work during pregnancy may confer an increased risk of miscarriage and indicates a lowest observed threshold level of two night shifts per week.

Factors associated with spontaneous abortion: a cross-sectional study of Chinese populations

Background

Spontaneous abortion (SA) is one of the prevalent negative reproductive outcomes among women around the world, which is a great challenge faced by maternal health promotion. The present study is aimed to explore the association between SA and socioeconomic status (SES) and provides reference for policy makers to improve strategies on maternal health promotion.

Methods

A cross-sectional analysis was conducted with baseline data from a large-scale population-based cohort study of 0.5 million people from 10 geographically diverse areas of China recruited from 2004 to 2008. The study collected data from 84,531 women aged 35–45 years old in the baseline survey of China Kadoorie Biobank. Participants were interviewed using a standardized questionnaire, and information on demographic-socioeconomic as well as reproductive health status was collected. Odds ratios (OR) with 95% CI, estimated by a multistep logistic regression, were used to approximate the associations between SA occurrence and characteristics of SES. A stratification analysis was also applied to find out how SES influenced women’s reproductive health outcomes differently between rural and urban areas. The model was adjusted for age at study date, tea consumption, alcohol consumption, cigarette smoking, and number of induced abortion.

Results

The risk of SA in rural was 1.68 times greater than in urban (AOR = 1.68, 95%CI: 1.54–1.84). Women with high income had a decreased risk of SA when compared with that of women with low income (AOR = 0.90, 95%CI: 0.84–0.97). Compared with women in low educational attainment, women in higher educational attainment had a lower prevalence of SA (AOR = 0.90, 95%CI: 0.82–0.98). The risk of SA only reduced in factory worker (AOR = 0.59, 95%CI: 0.53–0.66) and professional worker (AOR = 0.75, 95%CI: 0.66–0.84) compared with agriculture and related workers. After stratifying by rural/urban, the association between income and SA in urban (AOR = 0.88, 95%CI: 0.78–0.99) was stronger than that in rural (AOR = 0.92, 95%CI: 0.84–1.00). Association between education and SA was found in urban (AOR = 0.66, 95%CI: 0.55–0.78) but not in rural (AOR = 1.05, 95%CI: 0.34–1.17), and there was no difference on how occupation impacted SA among women between the two subgroups.

Conclusions

Generally women with lower SES status had a higher risk of SA. Lower income and educational attainment were inversely associated with the risk of SA. Women with agricultural and related work had a significantly higher prevalence of SA. Interventions could be targeted more on women with low SES to increase both health profits as well as economic gains for health programs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12978-017-0297-2) contains supplementary material, which is available to authorized users.

Exercise and pregnancy in recreational and elite athletes: 2016 evidence summary from the IOC expert group meeting, Lausanne. Part 2-the effect of exercise on the fetus, labour and birth

This is Part 2 of 5 in the series of evidence statements from the IOC expert committee on exercise and pregnancy in recreational and elite athletes. Part 1 focused on the effects of training during pregnancy and on the management of common pregnancy-related symptoms experienced by athletes. In Part 2, we focus on maternal and fetal perinatal outcomes.

Influence of shift work on early reproductive outcomes: a systematic review and meta-analysis

OBJECTIVE

To determine whether an association exists between shift work and early reproductive outcomes.

DATA SOURCES

MEDLINE, Embase, and Web of Science were searched. Additional sources included Google Scholar, the Cochrane Library, online publications of national colleges, the ClinicalTrials.gov, and references of retrieved papers.

METHODS OF STUDY SELECTION

Included studies compared female shift workers (work outside 8:00 AM to 6:00 PM) with nonshift workers with menstrual disruption (cycles less than 25 days or greater than 31 days), infertility (time-to-pregnancy exceeding 12 months), or early spontaneous pregnancy loss (less than 25 weeks).

TABULATION, INTEGRATION, AND RESULTS

Two reviewers extracted adjusted and raw data. Random effect models were used to pool data weighting for the inverse of variance. Assessments of heterogeneity, bias, and subgroup analyses were performed. Sixteen independent cohorts from 15 studies (123,403 women) were subject to analysis. Shift workers had increased rates of menstrual disruption (16.05% [2,207/13,749] compared with 13.05% [7,561/57,932] [n=71.681, odds ratio {OR} 1.22, 95% confidence interval {CI} 1.15-1.29, I 0%]) and infertility (11.3% [529/4,668] compared with 9.9% [2,354/23,811] [OR 1.80, 95% CI 1.01-3.20, I 94%]) but not early spontaneous pregnancy loss (11.84% [939/7,931] compared with 12.11% [1,898/15,673] [n=23,604, OR 0.96, 95% CI 0.88-1.05, I 0%]). Night shifts were associated with increased early spontaneous pregnancy loss (n=13,018, OR 1.29, 95% CI 1.11-1.50, I 0%). Confounder adjustment led to persistent relationships between shift work and menstrual disruption (adjusted OR 1.15, 95% CI 1.01-1.31, I 70%) but not infertility (adjusted OR 1.11 95% CI 0.86-1.44, I 61%). The association between night shifts and early spontaneous pregnancy loss remained (adjusted OR 1.41 95% CI 1.22-1.63, I 0%).

CONCLUSION

This review provides evidence for an association between performing shift work and early reproductive outcomes, consistent with later pregnancy findings. However, there is currently insufficient evidence for clinicians to advise restricting shift work in women of reproductive age.

Occupational lifting, fetal death and preterm birth: findings from the Danish National Birth Cohort using a job exposure matrix

Objective

We examined the association between occupational lifting during pregnancy and risk of fetal death and preterm birth using a job exposure matrix (JEM).

Methods

For 68,086 occupationally active women in the Danish National Birth Cohort, interview information on occupational lifting was collected around gestational week 16. We established a JEM based on information from women, who were still pregnant when interviewed. The JEM provided mean total loads lifted per day within homogeneous exposure groups as informed by job and industry codes. All women were assigned an exposure estimate from the JEM. We used Cox regression models with gestational age as underlying time variable and adjustment for covariates.

Results

We observed 2,717 fetal deaths and 3,128 preterm births within the study cohort. No exposure-response relation was observed for fetal death, but for women with a prior fetal death, we found a hazard ratio (HR) of 2.87 (95% CI 1.37, 6.01) for stillbirth (fetal death ≥22 completed gestational weeks) among those who lifted >200 kg/day. For preterm birth, we found an exposure-response relation for primigravid women, reaching a HR of 1.43 (95% CI 1.13, 1.80) for total loads >200 kg per day. These findings correspond to an excess fraction of 11% for stillbirth and 10% for preterm birth.

Conclusion

We found an increased risk of stillbirth among women with a prior fetal death, who lifted >200 kg/day, and an exposure-response relationship between occupational lifting and preterm birth among primigravid women. The study adds to a large body of prospective studies on occupational lifting and adverse pregnancy outcomes by refined exposure assessment.

Miscarriage and occupational activity: a systematic review and meta-analysis regarding shift work, working hours, lifting, standing, and physical workload

OBJECTIVE

Previous studies have indicated that shift work, long working hours, and prevalent workplace exposures such as lifting, standing, and physical workload increase the risk of miscarriage, but the evidence is conflicting. We conducted a systematic review of original research reports.

METHODS

A search in Medline and EMBASE 1966-2012 identified 30 primary papers reporting the relative risk (RR) of miscarriage according to ≥1 of 5 occupational activities of interest. Following an assessment of completeness of reporting, confounding, and bias, each risk estimate was characterized as more or less likely to be biased. Studies with equivalent measures of exposure were pooled to obtain a weighted common risk estimate. Sensitivity analyses excluded studies most likely to be biased.

RESULTS

Working fixed nights was associated with a moderately increased risk of miscarriage (pooled RR 1.51 [95% confidence interval (95% CI) 1.27-1.78, N=5), while working in 3-shift schedules, working for 40-52 hours weekly, lifting >100 kg/day, standing >6-8 hours/day and physical workload were associated with small risk increments, with the pooled RR ranging from 1.12 (3-shift schedule, N=7) to 1.36 (working hours, N=10). RR for working hours and standing became smaller when analyses were restricted to higher quality studies.

CONCLUSIONS

These largely reassuring findings do not provide a strong case for mandatory restrictions in relation to shift work, long working hours, occupational lifting, standing, and physical workload. Considering the limited evidence base, however, it may be prudent to advise women against work entailing high levels of these exposures and women with at-risk pregnancies should receive tailored individual counseling.

Relationship between handling heavy items during pregnancy and spontaneous abortion: a cross-sectional survey of working women in South Korea

The researchers conducted a cross-sectional survey to determine the relationship between handling heavy items during pregnancy and spontaneous abortion among working women in South Korea. One thousand working women were selected from a database of those eligible for maternity benefits under the National Employment Insurance Plan. Study results showed that handling heavy items during pregnancy was associated with an increased risk of spontaneous abortion after adjusting for general characteristics of the participants and their work environment. A collective effort is needed on the parts of employers, employees, occupational health nurses, and the government to protect working women from lifting heavy items while pregnant.

Relationship between handling heavy items during pregnancy and spontaneous abortion: a cross-sectional survey of working women in South Korea

The researchers conducted a cross-sectional survey to determine the relationship between handling heavy items during pregnancy and spontaneous abortion among working women in South Korea. One thousand working women were selected from a database of those eligible for maternity benefits under the National Employment Insurance Plan. Study results showed that handling heavy items during pregnancy was associated with an increased risk of spontaneous abortion after adjusting for general characteristics of the participants and their work environment. A collective effort is needed on the parts of employers, employees, occupational health nurses, and the government to protect working women from lifting heavy items while pregnant.

Assessment of time to pregnancy and spontaneous abortion status following occupational exposure to organic solvents mixture

PURPOSE

Due to increasing usage of chemicals in various industries, occupational exposure of women with these materials is unavoidable. Nowadays, some studies indicate adverse effects of exposure to these chemicals, especially organic solvents on the reproductive system of females. This study aimed to assess the relationship between spontaneous abortion and occupational exposure to organic solvents mixture in pharmaceutical industry.

METHODS

This study was carried out in a pharmaceutical factory located in the suburb of Tehran in 2010. During the study, married women who were working in the factory laboratory units and had exposure to mixed organic solvents were compared with married women who were working in the packing units of the factory without occupational exposure to organic solvents in terms of spontaneous abortion frequency and duration of pregnancy using statistical methods.

RESULTS

In this study, the frequency of spontaneous abortion in employees with and without exposure to organic solvents mixture was 10.7 and 2.9% respectively. This study showed that even after adjustment for confounding factors, there was a significant correlation between spontaneous abortion and occupational exposure to organic solvents mixture and this correlation increased with increasing levels of exposure to organic solvents. Also, a significant correlation was observed between occupational exposure to mixed organic solvents and waiting time to become pregnant (TTP). Furthermore, this study showed that even after adjustment for confounding variables, shift workers were significantly more affected by spontaneous abortion compared to daytime workers (P < 0.001). Also, in our study, synergistic effect between shift working and occupational exposure to organic solvents mixture on spontaneous abortion was seen.

CONCLUSIONS

According to the results of this study, since there is probability of spontaneous abortion resulting from occupational exposure to various chemicals including organic solvents, recommendation to review the status of occupational exposure of workers can be helpful in improving fertility consultations and reproductive health.

Maternal sleep deprivation, sedentary lifestyle and cooking smoke: Risk factors for miscarriage: A case control study

AIMS

To determine risk factors for miscarriage.

METHODS

A case control study was carried out at the gynaecological wards and antenatal clinics of the De Soysa Maternity Hospital in Sri Lanka. A case was defined as that of mothers with a confirmed diagnosis of partial or full expulsion of the fetus during the first 28 weeks of gestation. Controls comprised ante-natal clinic attendees whose period of gestation was <28 weeks and carrying a viable fetus. Two hundred and thirty cases and 504 controls were selected. A pre-tested interviewer-administered questionnaire and modified life events inventory were used to gather data. Multivariate logistic regression was applied separately for first and second trimester miscarriages and the results were expressed as odds ratios (OR) and as 95% confidence intervals (95% CI).

RESULTS

Sleeping < or =8 h/day (OR:3.80, 95% CI:1.01-14.3) was found to be a risk factor for first trimester miscarriage controlling for the effect of period of gestation. Sleeping < or =8 h/day (OR:2.04, 95% CI:1.24-3.37), standing < or =3 h/day (OR:1.83, 95% CI:1.08-3.10), exposure to cooking smoke (OR:3.83, 95% CI:1.50-9.90) and physical trauma during the pregnancy (OR:43.2, 95% CI:4.55-411.4) were found to be risk factors for second trimester miscarriage controlling for the effect of period of gestation.

CONCLUSIONS

Sleep deprivation, a sedentary lifestyle, exposure to cooking smoke and physical trauma during pregnancy were risk factors for miscarriage. Most of the risk factors are therefore modifiable.

Physical activity, physical exertion, and miscarriage risk in women textile workers in Shanghai, China

BACKGROUND

Strenuous occupational physical activity and physical demands may be risk factors for adverse reproductive outcomes.

METHODS

A retrospective study in the Shanghai, China textile industry study collected women's self-reported reproductive history. Occupational physical activity assessment linked complete work history data to an industry-specific job-exposure matrix. Odds ratios (OR) and 95% confidence intervals (CI) were estimated by multivariate logistic regression for the first pregnancy outcome and utilized generalized estimating equations to consider all pregnancies per woman.

RESULTS

Compared with women employed in sedentary jobs, a reduced risk of miscarriage was found for women working in jobs with either light (OR 0.18, 95% CI: 0.07, 0.50) or medium (OR 0.24, 95% CI: 0.08, 0.66) physical activity during the first pregnancy and over all pregnancies (light OR 0.32, 95% CI: 0.17, 0.61; medium OR 0.43, 95% CI: 0.23, 0.80). Frequent crouching was associated with elevated risk (OR 1.82, 95% CI: 1.14, 2.93; all pregnancies per woman).

CONCLUSIONS

Light/medium occupational physical activity may have reduced miscarriage risk, while specific occupational characteristics such as crouching may have increased risk in this cohort.

Employment in the Ecuadorian cut-flower industry and the risk of spontaneous abortion

BACKGROUND

Research on the potentially adverse effects of occupational pesticide exposure on risk of spontaneous abortion (SAB) is limited, particularly among female agricultural workers residing in developing countries.

METHODS

Reproductive histories were obtained from 217 Ecuadorian mothers participating in a study focusing on occupational pesticide exposure and children's neurobehavioral development. Only women with 2+ pregnancies were included in this study (n = 153). Gravidity, parity and frequency of SAB were compared between women with and without a history of working in the cut-flower industry in the previous 6 years. Logistic regression analysis was conducted to assess the relation between SAB and employment in the flower industry adjusting for maternal age.

RESULTS

In comparison to women not working in the flower industry, women working in the flower industry were significantly younger (27 versus 32 years) and of lower gravidity (3.3 versus 4.5) and reported more pregnancy losses. A 2.6 (95% CI: 1.03-6.7) fold increase in the odds of pregnancy loss among exposed women was observed after adjusting for age. Odds of reporting an SAB increased with duration of flower employment, increasing to 3.4 (95% CI: 1.3, 8.8) among women working 4 to 6 years in the flower industry compared to women who did not work in the flower industry.

CONCLUSION

This exploratory analysis suggests a potential adverse association between employment in the cut-flower industry and SAB. Study limitations include the absence of a temporal relation between exposure and SAB, no quantification of specific pesticides, and residual confounding such as physical stressors (i.e., standing). Considering that approximately half of the Ecuadorian flower laborers are women, our results emphasize the need for an evaluating the reproductive health effects of employment in the flower industry on reproductive health in this population.

Occupational physical activities, working hours and outcome of pregnancy: findings from the Southampton Women's Survey

OBJECTIVES

To investigate risks of physical activity at work by pregnancy trimester, including the effects on head and abdominal circumference.

METHOD

At 34 weeks of gestation we interviewed 1327 mothers from the prospective Southampton Women's Survey (SWS); we asked about their activities (working hours, standing/walking, kneeling/squatting, trunk bending, lifting and night shifts) in jobs held at each of 11, 19 and 34 weeks of gestation, and subsequently ascertained four birth outcomes (preterm delivery, small for gestational age (SGA) and reduced head or abdominal circumference) blinded to employment history.

RESULTS

Risk of preterm delivery was elevated nearly threefold in women whose work at 34 weeks entailed trunk bending for >1 h/day. Small head circumference was more common in babies born to women who worked for >40 h/week. However, no statistically significant associations were found with SGA or small abdominal circumference, and preterm delivery showed little association with long working hours, lifting, standing or shift work.

CONCLUSIONS

There is a need for more research on trunk bending late in pregnancy, and on the relationship of work to reduced head circumference. Our findings on several other occupational exposures common among pregnant workers are reassuring.

The influence of the environment and other exogenous agents on spontaneous abortion risk

It is estimated that close to 30% of all pregnancies end in spontaneous abortion. Although about 60% of spontaneous abortions are thought to be due to genetic, infectious, hormonal, and immunological factors, the role of the environment remains poorly understood. Pregnancy involves a delicate balance of hormonal and immunological functions, which may be affected by environmental substances. Many toxic substances that are persistent in the environment and accumulate in the fatty tissues may disrupt this equilibrium. This overview addresses known risk factors for spontaneous abortions and examines the role, if any, that environmental factors (chemical and physical) may play in the etiology of this adverse health outcome.

Work Schedule During Pregnancy and Spontaneous Abortion

BACKGROUND

There is inconsistent evidence as to whether work schedule (including rotating shifts and night work) can affect reproductive outcomes.

METHODS

We investigated the association between work schedule and risk of spontaneous abortion in U.S. nurses. The Nurses' Health Study II is a prospective cohort study established in 1989. In 2001, information about occupational activities and exposures during pregnancy was collected from female nurses for the most recent pregnancy since 1993. Of 11,178 eligible respondents, 9547 (85%) indicated willingness to participate in the occupational study, and 8461 of those (89%) returned the questionnaire, for an overall participation rate of 76%. Of these, 7688 women had pregnancies that were eligible for analysis.

RESULTS

Participants reported 6902 live births and 786 (10%) spontaneous abortions. Compared with women who reported usually working "days only" during their first trimester, women who reported usually working "nights only" had a 60% increased risk of spontaneous abortion (RR = 1.6; 95% confidence interval [CI] = 1.3-1.9). A rotating schedule, with or without night shifts, was not associated with an increase in risk (RR = 1.2 [CI = 0.9-1.5] and 1.0 [CI = 0.8-1.2], respectively). Women who reported working more than 40 hours per week during the first trimester were also at increased risk of spontaneous abortion (1.5; 1.3-1.7) compared with women working 21-40 hours, even after adjustment for work schedule.

CONCLUSIONS

Nightwork and long work hours may be associated with an increased risk of spontaneous abortion. Further studies are needed to determine whether hormonal disturbances attributed to night work affect pregnancy outcome.

Risk factors for first trimester miscarriage--results from a UK-population-based case-control study

OBJECTIVE

The aim of this study was to examine the association between biological, behavioural and lifestyle risk factors and risk of miscarriage.

DESIGN

Population-based case-control study.

SETTING

Case-control study nested within a population-based, two-stage postal survey of reproductive histories of women randomly sampled from the UK electoral register.

POPULATION

Six hundred and three women aged 18-55 years whose most recent pregnancy had ended in first trimester miscarriage (<13 weeks of gestation; cases) and 6116 women aged 18-55 years whose most recent pregnancy had progressed beyond 12 weeks (controls).

METHODS

Women were questioned about socio-demographic, behavioural and other factors in their most recent pregnancy.

MAIN OUTCOME MEASURE

First trimester miscarriage.

RESULTS

After adjustment for confounding, the following were independently associated with increased risk: high maternal age; previous miscarriage, termination and infertility; assisted conception; low pre-pregnancy body mass index; regular or high alcohol consumption; feeling stressed (including trend with number of stressful or traumatic events); high paternal age and changing partner. Previous live birth, nausea, vitamin supplementation and eating fresh fruits and vegetables daily were associated with reduced risk, as were feeling well enough to fly or to have sex. After adjustment for nausea, we did not confirm an association with caffeine consumption, smoking or moderate or occasional alcohol consumption; nor did we find an association with educational level, socio-economic circumstances or working during pregnancy.

CONCLUSIONS

The results confirm that advice to encourage a healthy diet, reduce stress and promote emotional wellbeing might help women in early pregnancy (or planning a pregnancy) reduce their risk of miscarriage. Findings of increased risk associated with previous termination, stress, change of partner and low pre-pregnancy weight are noteworthy, and we recommend further work to confirm these findings in other study populations.

Shift work, job stress, and late fetal loss: The National Birth Cohort in Denmark

OBJECTIVE

The Danish National Birth Cohort (DNBC) was used to examine whether shift work or job stress correlate with late fetal loss.

METHODS

We identified 33,694 pregnancies of daytime workers and 8,075 pregnancies of shift workers in women recruited to the DNBC between 1998 and 2001. Pregnancy outcomes were obtained by linkages to the national registers. Hazard ratios of fetal loss were calculated by using Cox regressions with left truncation.

RESULTS

Fixed night work was associated with fetal loss (hazard ratio = 1.85, 95% confidence interval = 1.00-3.42). No high risk of fetal loss was seen for other types of shift work. Job stress, as measured in our study, was not associated with fetal loss.

CONCLUSIONS

Our results suggest that fixed night work during pregnancy increases the risk of late fetal loss.

Vaginal bleeding in the first 20 weeks of pregnancy

The first and foremost diagnosis to exclude in the pregnant patient presenting with vaginal bleeding is ectopic pregnancy. Once ectopic pregnancy is ruled out, miscarriage should be considered as a clinical spectrum. Its management is directed according to the integrity of the internal cervical os and patient hemodynamic status. Treatment with anti-D immune globulin is warranted for all Rh-negative patients. Urgent obstetric consultation is necessary for most miscarriage presentations.

Strenuous work, nutrition and adverse pregnancy outcomes: a brief review

This brief review explores the available epidemiologic data to investigate the question of whether strenuous work by women during pregnancy in developing countries influences micronutrient status and thereby increase risks of adverse pregnancy outcomes. Some data exist on the potential relationship between strenuous work or physical activity and nutrient compromise, strenuous work or physical activity and adverse reproductive outcomes and micronutrient intakes or status and adverse reproductive outcomes. No substantial body of data exists that has directly investigated the potential causal path of whether strenuous work during pregnancy alters micronutrient status leading to adverse reproductive outcome. Search of the literature identified only a few papers from developing countries that provided even remotely related data on the topic. Thus, the available data are insufficient for drawing firm inferences that strenuous work, in a developing country, alters a pregnant woman's nutritional status and therefore affects her risk of an adverse pregnancy outcome. Effects on nutritional status, micronutrients in particular, of pregnant women from strenuous physical activities at work or in other lifestyle events require further study in developing countries.

Occupational physical activity and pregnancy outcome

OBJECTIVE

To determine the effect of occupational physical activities on the outcome of pregnancy.

METHODS

A case control study included two groups; the first one included 562 patients with spontaneous abortion as a case group, while the second one included 1200 ladies with full term deliveries as a matched control group. Occupational physical activity has been evaluated through the energy expenditure (fatigue score and intensity score) and the biomechanic load (abdominal pressure intensity score, relative chronic pressure and peak pressure scores) in both groups.

RESULTS

The group of spontaneous abortion had a significant higher intensity score, fatigue score, unfavourable working hours and high working speed than the group of favourable pregnancy outcome. The study showed a significantly higher biomechanic load among the group of spontaneous abortion represented by higher peak pressure score, chronic pressure score, lifting and bending activities. The group of spontaneous abortion had a significant (P<0.05) higher housekeeping working hours per day than that of the control group. Also they had a significant larger family size and had a significant lower helping in housekeeping activities than the group of favourable outcome.

CONCLUSION

Excessive occupational physical activity has a definite detrimental effect on the outcome of pregnancy.

Workplace reproductive problems

Occupational exposures can harm reproductive processes in men or women. Exposures may affect fertility, pregnancy outcomes or the child's health after delivery. The goal of patient management is to provide counseling at an appropriate level. Over-restricting the patient should be avoided while hazardous exposures should be identified and reduced. The occupational history can be used to estimate the magnitude of each exposure. If the exposure is a known reproductive hazard and the exposure level appears significant, there are several options for making the job safer. Modifications in work practices can be accomplished by advising the patient about changing work practices, writing formal work restrictions and talking with the employer. Temporary job transfers may be available. In some cases, a medical leave is needed. The primary care provider can play a key role in assisting patients to reduce reproductive risks.

Spontaneous abortion and physical strain around implantation: a follow-up study of first-pregnancy planners

Existing studies of physical strain and spontaneous abortion are mainly retrospective or based only on pregnancies that have survived the first trimester. Furthermore, almost all studies have relied on averaged measures of physical strain, which tend to blur an effect if peak values during short time periods are the relevant measure. We followed a cohort of first pregnancy planners from termination of birth control until pregnancy for a maximum of six menstrual cycles. The analyses include 181 pregnancies, of which 32 were subclinical pregnancies detected by hCG analysis only. During early pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later spontaneous abortion. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date of ovulation was 2.5 (95% CI = 1.3-4.6).