title: Reduced fertilization rates in older men when cervical mucus is suboptimal.
abstract: OBJECTIVE
  Cervical mucus is vital in the regulation of sperm survival and transport through the reproductive tract. The goal of this study is to assess whether the lowered fertility for men in their late 30s and early 40s is related to the nature of cervical mucus on the day of intercourse.
  
  
  METHODS
  In a prospective study of 7 European family planning centers, 782 couples not using birth control recorded daily observations of intercourse and the nature of cervical mucus. Using data from 1,459 menstrual cycles, 342 ending in pregnancy, we estimate day-specific conception probabilities in relation to mucus and male and female age.
  
  
  RESULTS
  On days where cervical mucus was not evident, intercourse for men in their late 30s and early 40s was 50% less likely to result in a clinical pregnancy, adjusting for intercourse timing and female age. As secretions become more conducive to sperm transport, the effect of male age diminishes steadily from 21% on days with damp secretions, to 11% on days with thick mucus, to only 4% on days with most fertile-type mucus.
  
  
  CONCLUSIONS
  The effect of male age on fecundability can be minimized by timing intercourse on days with optimal secretions.
  
  
  METHODS
  II-2.
authors.affiliation: National Institute of Environmental Health Sciences, U.S. National Institutes of Health, Research Triangle Park, North Carolina 27709, USA. dunson1@niehs.nih.gov
authors.forename: David B
authors.initials: DB
authors.lastname: Dunson
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Bigelow
authors.forename: Bernardo
authors.initials: B
authors.lastname: Colombo
mesh_terms: D000328:Adult; D000375:Aging; D002582:Cervix Mucus / Q000502:physiology*; D003075:Coitus; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008597:Menstrual Cycle; D011247:Pregnancy; D018873:Pregnancy Rate; D011446:Prospective Studies; D013081:Sperm Motility / Q000502:physiology*