Comparative effects of a contraceptive vaginal ring delivering a nonandrogenic progestin and continuous ethinyl estradiol and a combined oral contraceptive containing levonorgestrel on hemostasis variables

Objective

This study aimed to compare the effects on hemostasis variables of a contraceptive vaginal ring with those of an oral contraceptive.

Study design

Twenty-three and 22 healthy premenopausal women were randomized to the contraceptive vaginal ring (150 μg Nestorone and 15 μg ethinyl estradiol) or Stediril 30 during 3 cycles. Analysis of covariance was performed with baseline values as covariate.

Results

The contraceptive vaginal ring changed most hemostasis variables similarly but raised (95% confidence intervals of percent treatment differences) Factor VIIt (28% to 49%), extrinsic activated protein C resistance (14% to 65%), and sex hormone–binding globulin (117% to 210%) and lowered Protein S (−32% to −16%) and the global activated partial thromboplastin time-based activated protein C resistance (−12% to −2%) more than the oral contraceptive.

Conclusion

The contraceptive vaginal ring affected some measured hemostasis variables and sex hormone–binding globulin differently from the oral contraceptive, most likely because of difference in androgenicity of the progestins. The results suggest that the contraindications for oral contraceptive use would also apply to the tested contraceptive vaginal ring.

Key words: Coagulation, Contraceptive vaginal ring, Nestorone, Oral contraceptives, Venous thromboembolism