title: Physically demanding work, fetal growth and the risk of adverse birth outcomes. The Generation R Study.
abstract: OBJECTIVE
  Work-related risk factors, such as long work hours, and physically demanding work have been suggested to adversely influence pregnancy outcome. The authors aimed to examine associations between various aspects of physically demanding work with fetal growth in different trimesters during pregnancy and the risks of adverse birth outcomes.
  
  
  METHODS
  Associations between physically demanding work and fetal growth were studied in 4680 pregnant women participating in a population-based prospective cohort study from early pregnancy onwards in The Netherlands (2002-2006). Mothers who filled out a questionnaire during mid-pregnancy (response 77% of enrolment) were included if they conducted paid employment and had a spontaneously conceived singleton live born pregnancy. Questions on physical workload were obtained from the Dutch Musculoskeletal Questionnaire and concerned questions on lifting, long periods of standing or walking, night shifts and working hours. Fetal growth characteristics were repeatedly measured by ultrasound and were used in combination with measurements at birth.
  
  
  RESULTS
  There were no consistent significant associations between physically demanding work nor working hours in relation to small for gestational age, low birth weight or preterm delivery. Women exposed to long periods of standing had lower growth rates for fetal head circumference (HC), resulting in a reduction of approximately 1 cm (3%) of the average HC at birth. Compared with women working <25 h/week, women working 25-39 h/week and >40 h/week had lower growth rates for both fetal weight and HC, resulting in a difference of approximately 1 cm in HC at birth and a difference of 148-198 g in birth weight.
  
  
  CONCLUSIONS
  Long periods of standing and long working hours per week during pregnancy seem to negatively influence intrauterine growth.
authors: The Generation R Study Group, and Department of Public Health, Erasmus Medical Center, Rotterdam, The Netherlands.
authors: Claudia A
authors: CA
authors: Snijder
authors: Teus
authors: T
authors: Brand
authors: Vincent
authors: V
authors: Jaddoe
authors: Albert
authors: A
authors: Hofman
authors: Johan P
authors: JP
authors: Mackenbach
authors: Eric A P
authors: EA
authors: Steegers
authors: Alex
authors: A
authors: Burdorf
mesh_terms: D000328:Adult; D001724:Birth Weight; D004651:Employment; D005260:Female; D047109:Fetal Development; D020567:Fetal Weight; D006257:Head / Q000196:embryology; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D018811:Maternal Exposure; D009035:Mothers; D009068:Movement; D009426:Netherlands / Q000453:epidemiology; D016273:Occupational Exposure; D009790:Occupations; D005082:Physical Exertion; D011247:Pregnancy; D011248:Pregnancy Complications; D011256:Pregnancy Outcome; D011264:Pregnancy Trimesters; D047928:Premature Birth; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D016138:Walking; D014937:Work