title: Variability in the hormonally estimated fertile phase of the menstrual cycle.
abstract: The purpose of this study was to determine the variability in length of the fertile phase of the menstrual cycle with 140 participants who produced 1,060 cycles with an electronic hormonal fertility monitor. The length of the fertile phase, as defined by the first day with a threshold level of urinary E3G and ending with a second day above a threshold of LH, varied from <1 to >7 days, with the most frequent length being 3 days.
authors.affiliation: College of Nursing, Institute for Natural Family Planning, Marquette University, Milwaukee, Wisconsin 53201-1881, USA. Richard.fehring@marquette.edu
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Fehring
authors.forename: Mary
authors.initials: M
authors.lastname: Schneider
mesh_terms: D000293:Adolescent; D000328:Adult; D004967:Estrogens / Q000032:analysis*; D004970:Estrone / Q000031:analogs & derivatives* / Q000652:urine; D005260:Female; D046910:Fertile Period / Q000378:metabolism*; D005298:Fertility / Q000502:physiology*; D006801:Humans; D007986:Luteinizing Hormone / Q000032:analysis*; D010061:Ovulation Detection / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D004967:Estrogens; C015856:estrone-3-glucuronide; D004970:Estrone; D007986:Luteinizing Hormone