Window of fertility not always gauged accurately, researcher finds

Women who are trying to become pregnant may not be using the most accurate predictor of fertility, says a researcher who has studied the best method of gauging the “window of fertility.”

That window is the six-day period during which conception can occur. It consists of the five days before ovulation and the day of ovulation itself.

But the greatest probability of conception results from intercourse one or two days before ovulation, not the day of ovulation as had been thought, says Dr. Joseph B. Stanford, coauthor of a review of fertility detection methods in the December issue of the journal Obstetrics and Gynecology and an associate professor in the department of family and preventive medicine at the University of Utah in Salt Lake City.

Calendar calculations and basal body temperature aren’t as useful as identifying the approximately five days leading up to ovulation. Urine tests for the surge of luteinizing hormone that occurs a day or two before ovulation identify only a small part of the fertile window.

Methods that do reveal the complete window of fertility are those that evaluate changes in vaginal discharge or that assess estrogen levels in urine or saliva.

-- Dianne Partie Lange