title: Use of time to pregnancy in environmental epidemiology and surveillance.
abstract: BACKGROUND
  Potential sources of environmental pollution, such as incinerators or landfill sites, can adversely affect reproduction and/or development. Time to pregnancy (TTP) is a validated measure of biological fertility that can be studied with relatively small populations.
  
  
  METHODS
  Pregnant local residents living within 3 km of a landfill site ('exposed' group, n = 200) or elsewhere in the Rhondda valleys ('unexposed' group, n = 400) were interviewed by health visitors or midwives. The response rate was 83%.
  
  
  RESULTS
  No difference was found in the TTP distributions between the exposed and unexposed groups. Relationships of TTP with covariates were consistent with the literature.
  
  
  CONCLUSIONS
  In a context of public and scientific concern about possible reproductive toxicity, an interview study of TTP was highly acceptable to local women. A large enough sample to generate stable TTP distributions was readily achieved.
authors.affiliation: Department of Epidemiology and Public Health, Imperial College, St Mary's Campus, Norfolk Place, London W2 1PF, UK. m.joffe@imperial.ac.uk
authors.forename: Mike
authors.initials: M
authors.lastname: Joffe
authors.forename: Shantini
authors.initials: S
authors.lastname: Paranjothy
authors.forename: Hilary
authors.initials: H
authors.lastname: Fielder
authors.forename: Ronan
authors.initials: R
authors.lastname: Lyons
authors.forename: Stephen
authors.initials: S
authors.lastname: Palmer
mesh_terms: D000328:Adult; D004781:Environmental Exposure / Q000009:adverse effects*; D004784:Environmental Monitoring / Q000379:methods; D004785:Environmental Pollutants / Q000506:poisoning*; D004812:Epidemiologic Methods; D062665:Epidemiological Monitoring; D005260:Female; D005298:Fertility / Q000187:drug effects*; D006801:Humans; D007247:Infertility, Female / Q000139:chemically induced* / Q000453:epidemiology; D011247:Pregnancy / Q000706:statistics & numerical data*; D017584:Reproductive History; D012959:Socioeconomic Factors; D013997:Time Factors; D014852:Wales
chemical_list: D004785:Environmental Pollutants