The biphasic pattern of end-expiratory carbon dioxide pressure: a method for identification of the fertile phase of the menstrual cycle

D. Hadžiomerović, Kay Moeller, Peter B. Licht, A Hein, Achim Hein, Stephan Veitenhansel, Martina Kusmitsch, L. Wildt
In: Fertility and Sterility · 2007 · vol. 90(3) , pp. 731–736 · doi:10.1016/j.fertnstert.2007.06.078 · PMID:17936278 · W2015651039
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Abstract

ObjectiveTo examine the changes of end-tidal carbon dioxide pressure (P(ET)CO(2)) during the menstrual cycle.DesignControlled clinical study.SettingDepartment of Gynecologic Endocrinology and Reproductive Medicine, Medical University of Innsbruck, Austria.Patient(s)One hundred sixty women with a history of regular menstrual cycles were studied.Intervention(s)The P(ET)CO(2) was determined once daily. Monitoring of the cycles was performed by ultrasonography and determination of E(2), P, and LH in blood or LH in urine samples.Main outcome measure(s)The changes in P(ET)CO(2) during the ovulatory and anovulatory cycles were analyzed.Result(s)The time course of P(ET)CO(2) followed a biphasic pattern with luteal phase values being on average 6.5 +/- 2.5 mm Hg lower than during the follicular phase. The decrease of P(ET)CO(2) started, coincident with the increase of E(2), 1-8 days (median: 4.5 days) before onset of the LH surge. No such changes in P(ET)CO(2) could be observed during the anovulatory cycles. These changes could be mimicked by administration of E(2) or P. The P(ET)CO(2) did not exhibit a circadian rhythm and was not influenced by normal physical activity.Conclusion(s)The P(ET)CO(2) changes in a characteristic way during the menstrual cycle. Determination of P(ET)CO(2) appears to be a promising method for the detection of the fertile phase of the menstrual cycle in the context of natural family planning.

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