Determination of the fertile window: reproductive competence of women--European cycle databases.

Objectives. The objective of the present paper is to review the main results of recent European cycle databases on ovulation detection and determination of the fertile window performed by the women themselves.Methods. The ongoing German Long-term Cycle Database currently comprises 32 788 prospectively collected cycle charts of 1551 women, the I European Cycle Database (10 countries) 1328 women/19 048 cycles, the II European Cycle Database (six countries) 782 women/6724 cycles, and the World Health Organization Database (one European country) 234 women/2808 cycles. The women record cycle parameters (cervical mucus changes, temperature rise, etc.), family planning intention and sexual behavior.Results. With the symptothermal method of natural family planning it has become possible to determine the fertile window in order to avoid pregnancy with a method effectiveness of 0.3%. According to a small sub-study, the ovulation time observed by the women themselves correlates closely with ovulation detected by ult...