title: The effects of work-related maternal risk factors on time to pregnancy, preterm birth and birth weight: the Generation R Study.
abstract: OBJECTIVE
  To investigate the influence of maternal working conditions on fertility and pregnancy outcomes.
  
  
  METHODS
  8880 women were enrolled in a large prospective birth cohort during early (76%), mid (21%) or late pregnancy (3%) (61% participation). Complete questionnaire information was available for 6302 women (71% response). Outcomes were prolonged time to pregnancy (TTP) (> 6 months), preterm birth (< 37 weeks) and decreased birth weight (< 3000 g). Self-reported exposure to chemical agents was based on a limited list of chemicals. Physical load questions concerned manual materials handling, prolonged sitting and long periods of standing. A job-exposure matrix (JEM) linked reported job title to workplace chemical exposure within jobs according to expert judgement. Associations between maternal occupational exposure and fertility and pregnancy outcomes, adjusted for age, education, minority, parity, smoking and alcohol use, were studied using logistic regression analysis.
  
  
  RESULTS
  Women in jobs with regular handling of loads ≥ 5 kg had better fertility and pregnancy outcomes. No self-reported exposure to chemicals was associated with any outcomes and self-assessments had very low reliability compared with JEM-based assessments. JEM-based maternal occupational exposure to phthalates was associated with prolonged TTP (OR 2.16, 95% CI 1.02 to 4.57) and exposure to pesticides was associated with decreased birth weight (OR 2.42, 95% CI 1.10 to 5.34). The population attributable fractions were small at 0.7% for phthalates and 0.7% for pesticides.
  
  
  CONCLUSIONS
  This birth cohort study presents evidence of health-based selection into the workforce and adverse effects of maternal occupational exposure to phthalates and pesticides on fertility and pregnancy outcomes.
authors.affiliation: Department of Public Health, Erasmus MC, University Medical Center Rotterdam, PO Box 2040, 3000 CA Rotterdam, The Netherlands. a.burdorf@erasmusmc.nl
authors.forename: A
authors.initials: A
authors.lastname: Burdorf
authors.forename: T
authors.initials: T
authors.lastname: Brand
authors.forename: V W
authors.initials: VW
authors.lastname: Jaddoe
authors.forename: A
authors.initials: A
authors.lastname: Hofman
authors.forename: J P
authors.initials: JP
authors.lastname: Mackenbach
authors.forename: E A P
authors.initials: EA
authors.lastname: Steegers
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D001724:Birth Weight; D015986:Confounding Factors, Epidemiologic; D004522:Educational Status; D004812:Epidemiologic Methods; D005260:Female; D005298:Fertility; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D008875:Middle Aged; D009043:Motor Activity; D009426:Netherlands / Q000453:epidemiology; D009784:Occupational Diseases / Q000453:epidemiology / Q000209:etiology; D016273:Occupational Exposure / Q000009:adverse effects*; D010575:Pesticides / Q000633:toxicity; D010795:Phthalic Acids / Q000633:toxicity; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000453:epidemiology*; D047928:Premature Birth / Q000453:epidemiology / Q000209:etiology; D013997:Time Factors; D055815:Young Adult
chemical_list: D010575:Pesticides; D010795:Phthalic Acids