Research
General gynecology
Oral contraceptive effectiveness according to body mass index, weight, age, and other factors

Presented as a poster at the 55th Annual Clinical Meeting of the American College of Obstetricians and Gynecologists, San Diego, CA, May 5-9, 2007.
https://doi.org/10.1016/j.ajog.2009.03.017Get rights and content

Objective

The purpose of this study was to assess the use-effectiveness of oral contraceptives (OCs) in Europe according to body mass index (BMI), weight, age, and other factors.

Study Design

In a planned secondary analysis, we used data from the European Active Surveillance Study on Oral Contraceptives, which was a prospective active cohort surveillance study of 59,510 OC users, to assess the effectiveness of OCs overall and by BMI, weight, age, duration of use, ethinylestradiol dose, regimen type, starting/switching status, and parity. Self-reported unplanned pregnancies during OC use were confirmed by interview.

Results

An analysis of OC effectiveness (112,659 women-years of exposure and 545 unplanned pregnancies) found little variation in effectiveness by BMI/weight. Failure rates decreased after 30 years of age and with an increasing duration of use.

Conclusion

OC users in Europe reported high contraceptive effectiveness with “typical use.” Failure rates decreased with age and duration of use. BMI and weight had little, if any, influence on effectiveness.

Section snippets

Study design

EURAS-OC was a large-scale, prospective, active cohort surveillance study conducted between 2000 and 2005 that characterized and compared the short- and long-term risks of both drospirenone-containing and other progestin-containing OCs in a large cohort of OC users in Europe. The main clinical outcome of interest in EURAS-OC was the occurrence of cardiovascular events (ie, the occurrence of venous thromboembolism, myocardial infarction, stroke, arrhythmia, and sudden death). Secondary a

Results

A total of 59,510 women were enrolled in EURAS-OC. Of these, 836 women were excluded because of protocol violations (failure to sign an informed consent form, enrolled ≥2 times by ≥1 study center, continued use of an existing OC, or failure to initiate treatment). Overall, 58,674 women were observed for 142,475 WYs. The maximum individual duration of follow-up evaluation was up to 5 years (mean, 2.4 years). Overall, 1401 women (2.4%) were lost to follow-up during the study (Figure 1).

The

Comment

The results of the current analysis, which was conducted in a large cohort of women from several European countries and based on a total OC exposure of 112,659 WYs, showed that OCs are associated with high contraceptive effectiveness during routine use in women in Europe. Both increasing age (for age groups of >24 years) and increasing duration of use were associated with lower contraceptive failure rates. Although BMI and absolute weight had little, if any, influence on the contraceptive

Acknowledgments

We thank Lyndal McMillan and Danielle Turner from Wolters Kluwer Health for writing assistance during the preparation of this article.

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    Cite this article as: Dinger JC, Cronin M, Möhner S, et al. Oral contraceptive effectiveness according to body mass index, weight, age, and other factors. Am J Obstet Gynecol 2009;201:263.e1-9.

    Financial support was provided by Bayer Schering Pharma AG, Berlin, Germany.

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