Oral contraceptives and antithrombin III: Variations by dosage and ABO blood group

Ronald T. Burkman, William R. Bell, Howard A. Zacur, Allyn W. Kimball

Research output: Contribution to journalArticle

Abstract

A randomized clinical trial of oral contraceptives evaluated 67 women on a regimen of 50 μg ethinyl estradiol and 1.0 mg norethindrone, 61 women on a regimen of 35 Kg ethinyl estradiol and 1.0 mg norethindrone, and 64 women on a regimen of 35 μg ethinyl estradiol and 0.5 mg norethindrone. ABO blood group type was determined in all women. At baseline and at 3, 6, and 9 months, plasma antithrombin III levels, by both an immunologic and an activity method, and selected plasma levels of the contraceptive steroids were measured. Antithrombin III levels for all oral contraceptive groups combined decreased from baseline by 19.7% and 28.8% for the immunologic and activity methods, respectively. Analysis of interrelationships among antithrombin III by activity method, oral contraceptive type, and ABO blood group showed larger declines in antithrombin III for type O women using the highest estrogen dose preparation (31.6%) and for non-type O women using the lowest progestin dose preparation (38.9%). Plasma levels of contraceptive steroids also were related to changes in the most extreme levels of antithrombin III.

Original languageEnglish (US)
Pages (from-to)1453-1460
Number of pages8
JournalAmerican journal of obstetrics and gynecology
Volume164
Issue number6 PART 1
DOIs
StatePublished - Jun 1991

Keywords

  • ABO blood group
  • Oral contraceptives
  • antithrombin 111

ASJC Scopus subject areas

  • Obstetrics and Gynecology

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