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

ObjectivesTo 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.MethodsPregnant 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.ResultsProlonged 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).ConclusionThis 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.

O6C.3 The association between long-term exposure from heavy physical work load and coronary heart disease in middle aged men

ObjectivesPrevious studies have shown conflicting results concerning the association between heavy physical work load and risk of coronary heart disease (CHD). The aim of this study was to investigate the association between long-term exposure to heavy physical work load in middle age and risk of CHD among Swedish men during almost 20 years of follow-up.MethodsThe study is based on a cohort of around 40 000 Swedish males, born 1949–51, with census information on occupation in 1985 and 1990 (at ages 34–41). Aspects of physical workload was estimated from job exposure matrices based on questions concerning heavy lifting, strenuous work postures, and physically strenuous work from the Swedish Work Environment Surveys 1989–97. Mean values for each physical exposure variable were assigned to over 300 occupational titles from the censuses conducted in 1985 and 1990. Only those 29 530 subjects who were in the same quintile of exposure both years were included in the analyses. Information on smoking behavior and body mass index (BMI) was collected at compulsory conscription for military training in 1969/70 (at 18–20 years of age), and follow up data on CHD (1457 cases) between the years 1991–2009.ResultsAn increased relative risk of CHD were found among workers in the quintiles with medium low (HR=1.36 CI95%=1.14–1.62), medium (HR=1.46 CI95%=1.23–1.74), medium-high (HR=1.62 CI95%=1.36–1.91), and high (HR=1.45 CI95%=1.22–1.71) exposure to heavy lifting at work compared with those in the quintile with low exposure to heavy lifting. After adjustment for smoking and BMI the risk estimates were somewhat lower but still significantly increased. Risk estimates of the same magnitude were seen for a number of other aspects of the physical work environment.ConclusionThere was an association between long-term exposure from heavy physical work load and CHD even after adjustement for smoking and BMI.

O8D.6 High physical workload and disability pension: a follow-up study of swedish men until 59 years of age

BackgroundIn Sweden, the proportion of the population that remains in paid employment until normal retirement age of 65 years is less than 50% in blue-collar groups, compared to 60%–75% in white-collar occupations. High physical workload has been associated with early exits from the labor market through disability pensions (DP) in many studies. However, identified risk factors for DP from early life may be more prevalent among men in heavy manual occupations than in others. The aim was to investigate the association between high physical work load in middle age and DP before age 59, adjusting for social background, physical ability, psychological characteristics, lifestyle and education measured before labour market entrance.MethodsThe study is based on a Swedish conscription cohort of 49 321 men born 1949–1951. At enlistment 1969/1970 information was collected about cardiorespiratory fitness, social background, psychological characteristics and health behaviours, e.g. smoking. Physical workload was estimated with a job exposure matrix based on questions concerning heavy lifting, strenuous work postures, repetitive work and physically strenuous work from the Swedish Work Environment Surveys 1989–97. Mean values for men of a composite physical exposure variable were grouped into quartiles; high, medium-high, medium-low and low physical workload, and assigned to occupational titles from the census 1990. The study group was followed regarding DP from age 40 to 59.ResultsExposure to high (HR 2.67, CI 95% 2.42–2.95), medium-high (HR 2.43, CI 95% 2.20–2.69) and medium-low (HR 1.31, CI 95% 1.18–1.47) physical workload, compared with low, were associated with DP up to age 59. The increased risks remained, but were clearly attenuated after adjustments for pre-labour market factors, especially psychological characteristics and education.ConclusionThe results are in line with a major effect of high physical work load on disability pension, even though adjustments for pre-labour market factors clearly attenuated the risks.

To what extent do education and physical work load factors explain occupational differences in disability retirement due to knee OA? A nationwide register-based study in Finland

ObjectivesTo examine the association of education and physical work load factors on the occupational differences in disability retirement due to knee osteoarthritis (OA).DesignLongitudinal study.SettingLinkage of several nationwide registers and a job exposure matrix in Finland.ParticipantsA total of 1 135 654 Finns aged 30–60 years in gainful employment were followed from 2005 to 2013 for full disability retirement due to knee OA.Primary and secondary outcome measuresWe calculated age-adjusted incidence rates and examined the association of occupation, education and physical work load factors with disability retirement using competing risk regression model. Disability retirement due to other causes than knee OA, old-age retirement and death were treated as competing risk.ResultsA total of 6117 persons had disability retirement due to knee OA. Women had a higher age-adjusted incidence rate than men (72 vs 60 per 100 000 person-years, respectively). In men, a very high risk of disability retirement was found among construction workers, electricians and plumbers (HR 16.6, 95% CI 12.5 to 22.2), service workers (HR 12.7, 95% CI 9.2 to 17.4) and in women among building caretakers, cleaners, assistant nurses and kitchen workers (HR 15.5, 95% CI 11.7 to 20.6), as compared with professionals. The observed occupational differences were largely explained by educational level and noticeably mediated by physical work load factors in both genders.ConclusionOur observational study suggests that the risk of disability retirement among manual workers is strongly attributed to the physically heavy work.