Elsevier

Obstetrics & Gynecology

Volume 88, Issue 6, December 1996, Pages 939-944
Obstetrics & Gynecology

Myocardial infarction in users of low-dose oral contraceptives*

https://doi.org/10.1016/S0029-7844(96)00351-1Get rights and content

Objective

To determine the relationship between the use of low-dose (less than 50 /mg estrogen) oral contraceptives (OC) and myocardial infarction.

Methods

In this population-based case-control study, all incident myocardial infarctions in women, ages 15–44 years who were members of the Kaiser Permanente Medical Care Program, Northern and Southern California regions were ascertained during a 39-month period from 1991 through 1994. For each woman with myocardial infarction, up to three age- and facility-matched controls were chosen at random from female members. Information about OC use (predominantly low-dose preparations) was obtained in face-to-face interviews.

Results

There were 187 incident cases of myocardial infarction during 3.6 million woman-years of observation (incidence rate, 5.2 per 100,000 woman-years). The prevalence of several risk factors for myocardial infarction was lower in controls who were current users of OCs than in controls who were noncurrent (past and never) users. The odds ratio for myocardial infarction in current OC users compared with noncurrent users was 1.65 (95% confidence interval 0.45, 6.06) after adjustment for major risk factors and for race and ethnicity, corresponding to an excess risk of less than one case per 100,000 woman-years. The study had 80% power to detect a relative risk of 2.3 (one-sided test, α = .05). The odds ratio of myocardial infarction in past OC users was not elevated.

Conclusion

With respect to myocardial infarction, low-dose oral contraceptives can be used safely by women who lack risk factors for coronary heart disease.

References (26)

  • AdamSA et al.

    Oral contraception and myo-cardial infarction revisited: The effects of new preparations and prescribing patterns

    Br J Obstet Gynaecol

    (1981)
  • MaguireMG et al.

    Increased risk of thrombosis due to oral contraceptives: A further report

    Am J Epidemiol

    (1979)
  • KruegerDe et al.

    Fatal myocardial infarction and the role of oral contraceptives

    Am J Epidemiol

    (1980)
  • Cited by (0)

    *

    This research was supported by contract N01-HD-3108 from the National Institute of Child Health and Development.

    View full text