title: [Preliminary study on measurement of human fecundity applicability of time to pregnancy with Japanese subjects].
abstract: BACKGROUND
  Debate has been continuing whether endocrine disrupting chemicals (EDC) in the environment affect human reproduction. We are planning to use time to pregnancy (TTP) as a measure of human fecundity to relate EDC exposure in a future research. TTP is expressed as the number of non-contracepting menstrual cycles or months required for a couple to conceive. An extended TTP might be considered to reflect an injury to reproductive processes. Since this parameter has never been measured in Japan. the present preliminary study aimed at establishing a Japanese version of the TTP questionnaire and determining if TTP could be reliably measured in Japan.
  
  
  METHODS
  We prepared a self-administered questionnaire that consisted of questions on TTP, sexual life and dietary habits. Women who visited a gynecology clinic in Tokyo for confirmation of pregnancy during the period October 2000 to March 2001 were the subjects asked to fill in the questionnaire. The results were statistically analyzed by chi-square test, t-test and binorminal logistic model after classifying the subjects into two groups: (a) Group I (TTP < or = 6 months; n = 53) (b) Group II (TTP > 6 months; n = 16)
  
  
  RESULTS
  Of the 92 women approached, 69 (75.0%) could report TTP. The distribution of TTP, the mode being around 1-2 months with a positive skew toward longer value, was similar to those reported so far in Western countries. There were statistically significantly more smokers in Group II (smoker 62.5%) than in I (15.6%). Logistic regression analysis indicated prior gravidity and fish and milk consumption, in addition to cigarette smoking, to be related to TTP.
  
  
  CONCLUSIONS
  The present preliminary study indicated that TTP surveys are feasible with Japanese based on the high response rate and plausible distribution of reported value. It also indicated that TTP was related to cigarette smoking, gravidity and dietary habits, again consistent with previous studies.
authors.affiliation: Institute of Environmental Studies, University of Tokyo.
authors.forename: Chikako
authors.initials: C
authors.lastname: Arakawa
authors.forename: Jun
authors.initials: J
authors.lastname: Yoshinaga
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Mizumoto
authors.forename: Masao
authors.initials: M
authors.lastname: Abe
mesh_terms: D000328:Adult; D005247:Feeding Behavior; D005260:Female; D005298:Fertility; D006801:Humans; D008297:Male; D010298:Parity; D011247:Pregnancy / Q000706:statistics & numerical data; D012907:Smoking / Q000453:epidemiology; D011795:Surveys and Questionnaires; D013942:Thymine Nucleotides; D013995:Time
chemical_list: D013942:Thymine Nucleotides; C024157:thymidine 5'-triphosphate