Effect of Past Hormonal Contraceptive Use on Blood, Salivary, and Urinary Progesterone Levels in Young Women

Shoko Konishi, The University of Tokyo
Eleanor Brindle, University of Washington
Kathleen A. O'Connor, University of Washington

We examined the effect of previous hormonal contraceptive use on progesterone levels in dried blood spots, saliva, and urine. Fifty-eight women aged 18-34 years who had not used hormonal contraceptives in the past 3 months collected weekly samples for 4 weeks across the menstrual cycle (N=232 samples matched specimens from blood, saliva, and urine). Progesterone levels determined by ELISA were adjusted for age, BMI, ethnicity, menstrual cycle phase, and repeated measures using a mixed-effects model. Compared to never-users, women who previously used hormonal contraceptives showed similar blood progesterone but lower salivary progesterone, which suggests a higher free fraction of the hormone in blood. Thus, the effects of hormonal contraceptives on hormone binding may persist years after discontinuing use. Urinary progesterone did not differ by past contraceptive use. When applying salivary progesterone in population research, it may be necessary to adjust for past hormonal contraceptive use.