title: Occupational lifting during pregnancy and risk of fetal death in a large national cohort study.
abstract: OBJECTIVE
  The aim of the present study was to examine the association between occupational lifting and the risk of fetal death according to gestational age.
  
  
  METHODS
  We used data from the Danish National Birth Cohort (1996-2002). Among 71,500 occupationally active women, 2886 experienced a fetal death. Information on lifting and relevant covariates was collected in interviews around week 16 of pregnancy. The majority of fetal losses (N=2032) happened before the scheduled interview, and exposure data were collected retrospectively from these women. We analyzed early miscarriage (≤12 weeks), late miscarriage (13-21 weeks), and stillbirth (≥22 weeks), using Cox-regression models with gestational age as the underlying time variable.
  
  
  RESULTS
  The adjusted early miscarriage risk increased with frequency of daily lifts and total burden lifted per day. For example, the hazard ratio was 1.38 [95% confidence interval (95% CI) 1.10-1.74] for a total weight load per day of 101-200 kg and 2.02 (95% CI 1.23-3.33) for a daily load >1000 kg as compared to non-lifters (P for trend <0.0001). Late miscarriage was associated with total daily weight load (P for trend=0.0073) but not with number of lifts per day. There was no association between occupational lifting and stillbirth.
  
  
  CONCLUSIONS
  In the present study, the risk of miscarriage increased with the number of lifts and total burden lifted per day at work. There may be a case for advising pregnant women against heavy lifting in particular during early pregnancy.
authors.affiliation: Section of Social Medicine, Department of Public Health, University of Copenhagen, Copenhagen, Denmark. metjuhl@gmail.com
authors.forename: Mette
authors.initials: M
authors.lastname: Juhl
authors.forename: Katrine
authors.initials: K
authors.lastname: Strandberg-Larsen
authors.forename: Pernille Stemann
authors.initials: PS
authors.lastname: Larsen
authors.forename: Per Kragh
authors.initials: PK
authors.lastname: Andersen
authors.forename: Susanne Wulff
authors.initials: SW
authors.lastname: Svendsen
authors.forename: Jens Peter
authors.initials: JP
authors.lastname: Bonde
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Nybo Andersen
mesh_terms: D000328:Adult; D003718:Denmark; D005260:Female; D005313:Fetal Death; D006801:Humans; D017770:Lifting; D016272:Occupational Health; D011247:Pregnancy; D016016:Proportional Hazards Models; D012307:Risk Factors