title: Lactose metabolism and time to pregnancy.
abstract: OBJECTIVE
  To investigate whether, in the absence of galactosemia, relatively high intestinal lactase activity or low activity of an enzyme involved in galactose catabolism reduces fertility, as it does in the presence of galactosemia.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Healthy women selected from the community.
  
  
  METHODS
  Fifty-three married women.
  
  
  METHODS
  Urinary galactose after an oral lactose challenge (a measure of intestinal lactase activity), erythrocyte galactose-1-phosphate uridyltransferase (transferase) activity, and transferase polymorphisms by isoelectric focusing.
  
  
  METHODS
  Pregnancy rate (number of pregnancies divided by number of months at risk) in the 12 months after stopping use of birth control to become pregnant.
  
  
  RESULTS
  Relatively high urinary galactose was not related to a decreased rate of pregnancy during the first 12 months (> or = 24.6 compared with < or = 14.3 mg: relative risk [RR] = 1.9; 95% confidence interval [CI] = 0.86 to 4.0). Relatively high transferase activity was not related to an increased rate of pregnancy (> or = 19.5 compared with < or = 17.2 mumol/h per g hemoglobin: RR = 1.1; 95% CI = 0.56 to 2.4). Low-activity transferase polymorphisms were not related to a decreased rate (RR = 1.2; 95% CI = 0.58 to 2.5).
  
  
  CONCLUSIONS
  Our study does not support the hypothesis that the biologic variation in galactose metabolism that exists in the general population influences infertility.
authors: University of Washington, Fred Hutchinson Cancer Research Center, Seattle, USA. ljh@dor.kaiser.org.us
authors: L J
authors: LJ
authors: Herrinton
authors: R N
authors: RN
authors: Lemaitre
authors: S A
authors: SA
authors: Beresford
authors: J L
authors: JL
authors: Stanford
authors: D M
authors: DM
authors: Wolfla
authors: Z
authors: Z
authors: Feng
authors: C R
authors: CR
authors: Scott
authors: N S
authors: NS
authors: Weiss
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D004912:Erythrocytes / Q000201:enzymology; D005260:Female; D005298:Fertility / Q000502:physiology; D005690:Galactose / Q000378:metabolism / Q000502:physiology / Q000652:urine; D006801:Humans; D007422:Intestines / Q000201:enzymology; D007785:Lactose / Q000378:metabolism* / Q000502:physiology / Q000652:urine; D008875:Middle Aged; D011110:Polymorphism, Genetic; D011247:Pregnancy / Q000378:metabolism* / Q000502:physiology; D018873:Pregnancy Rate; D012189:Retrospective Studies; D013997:Time Factors; D014166:Transferases / Q000097:blood / Q000235:genetics; D001616:beta-Galactosidase / Q000032:analysis
chemical_list: D014166:Transferases; D001616:beta-Galactosidase; D007785:Lactose; D005690:Galactose