Intended for healthcare professionals

Rapid response to:


The timing of the “fertile window” in the menstrual cycle: day specific estimates from a prospective study

BMJ 2000; 321 doi: (Published 18 November 2000) Cite this as: BMJ 2000;321:1259

Rapid Response:

Prediction of ovulation by home use ClearPlan Fertility Monitor

The well-designed study by Wilcox, Dunson and Baird clearly
demonstrates the variability of the ovulation day in the menstrual cycle.
This information might be of significant relevance for couples trying to
conceive, especially where the male partner has some degree of impaired
fertility, e.g. because of diminished progressive sperm motility
(Nieschlag & Behre, 2000). Optimisation of the timing between sexual
intercourse and ovulation could enhance chances of achieving a pregnancy.

In their introduction Wilcox et al. say that “Reliable methods to
predict ovulation are lacking, therefore predicting the fertile window is
also unreliable.” The method of daily urine sampling and assaying of
hormone concentrations to detect ovulation used in the study by Wilcox et
al. is not suitable for home use. In the December issue of Human
Reproduction we published the results of a prospective study on the
performance of the ClearPlan® Fertility Monitor (CPFM, Unipath Ltd.,
Bedford, U.K.) to predict and detect ovulation (Behre et al. 2000). The
CPFM comprises a hand-held monitor and disposable dual-assay urine test
sticks, which simultaneously detect LH and estrone-3-glucuronide
concentrations in early morning urine. In our study involving 53 women for
up to four consecutive menstrual cycles, ovulation was detected in 91.1%
of cycles during the 2 days of CPFM peak fertility display on the monitor,
and - of similar importance - never occurred before. Home use of CPFM
could help couples who desire pregnancy to time intercourse and may be
applied in the initial treatment of infertility.


Behre HM, Kuhlage J, Gassner C, Sonntag B, Schem C, Schneider HPG,
Nieschlag E. Prediction of ovulation by urinary hormone measurements with
the home use ClearPlan® Fertility Monitor: comparison with transvaginal
ultrasound scans and serum hormone measurements. Human Reproduction 2000

Nieschlag E, Behre HM. Andrology – Male Reproductive Health and
Dysfunction. 2nd edition. Springer, 2000.

Competing interests: No competing interests

10 December 2000
Hermann M Behre
Head of the Andrology Unit
Martin-Luther-University, Halle, Germany