Typical-use Pregnancy Rate Research Articles

Pregnancy Risk Among Oral Contraceptive Pill, Injectable Contraceptive, and Condom Users in Uganda, Zimbabwe, and Thailand

To estimate the probability of pregnancy for oral contraceptive pill (OCP), injectable contraceptive, and condom users in Uganda, Thailand, and Zimbabwe. This study is a secondary analysis of 5,224 women who participated in a prospective study evaluating the association between hormonal contraception and human immunodeficiency virus (HIV) acquisition. The overall 12-month cumulative probability of pregnancy of injectable contraceptive users was 0.6% (95% confidence interval [CI] 0.3-1.0), with similar risks in Uganda (0.3%, 95% CI 0-0.7), Thailand (0.6%, 95% CI 0-1.2), and Zimbabwe (1.0%, 95% CI 0.3-1.7). The 12-month cumulative probability of pregnancy for OCP users was 9.5% (95% CI 8.1-11.0%), with similar risks of pregnancy in Uganda and Zimbabwe (14.6%, 95% CI 11.7-17.4; and 10.2%, 95% CI 8.0-12.5, respectively) but substantially lower risk in Thailand (0.5%, 95% CI 0-1.2). The overall 12-month cumulative probability of pregnancy for women intending to use a given method at baseline was 2.0% (95% CI 1.4-2.6%) for injectable contraceptives, 15.7% (95% CI 14.1-17.3%) for OCPs, and 25.8% (95% CI 23.2-28.4) for condoms. Women in Thailand experienced lower pregnancy risk with condoms (18.4%, 95% CI 11.1-25.7) than in Uganda (29.5%, 95% CI 25.7-33.4), and Zimbabwe (23.3%, 95% CI 19.4-27.2). The overall risk of pregnancy for injectable contraceptive users was substantially lower than for oral contraceptive pill users. However, Thai participants had similarly low cumulative pregnancy probabilities for both methods. Women receiving contraceptive counseling should be informed that their experience with a given method may differ from the average or typical-use pregnancy rates often discussed during contraceptive counseling. Tailored counseling is necessary for women to make informed choices. II.

Effectiveness of the male latex condom: combined results for three popular condom brands used as controls in randomized clinical trials

Background Although public health programs invest heavily in the male latex condom, its efficacy in preventing pregnancy and sexually transmitted disease has been based primarily on in vitro and retrospective studies. Methods We combine the results from two randomized, controlled contraceptive efficacy trials that used commercial latex condoms brands (Ramses Sensitol™, LifeStyles™, Trojan-Enz™) in the control arms. Combining data from the two studies, we obtained longitudinal data covering 3526 menstrual cycles contributed by approximately 800 couples who used latex condoms exclusively for up to six menstrual cycles. Both trials also collected 3715 detailed breakage and slippage reports from the first five study condom uses. The second trial also tested 243 postcoital vaginal samples collected after the first study condom use for the presence of prostate-specific antigen (PSA) and spermatazoa. Results The combined clinical breakage rate for the first five condom uses was 0.4% for the three latex brands and the combined clinical slippage rate was 1.1%. The combined six-cycle typical-use pregnancy rate for the latex condoms was 7.0% (95% confidence interval 5.0–9.0). The combined six-cycle consistent-use pregnancy rate was 1.0% (95% confidence interval 0.0–2.1). PSA was detected in only 1.2% of postcoital vaginal samples collected after the first use of an intact study condom. There were no differences in performance or efficacy among the three latex brands tested. Conclusions The male latex condoms rarely broke or slipped off during intercourse and provided high contraceptive efficacy, especially when used consistently. Risk of semen leakage from intact condoms was very low.

The importance of screening and monitoring: the Standard Days Method and cycle regularity

The Standard Days Method™ is a simple fertility awareness-based method of family planning with a correct-use pregnancy rate of 4.8 at 1 year and a typical-use pregnancy rate of 12. The protocol for providing the method includes guidelines for screening potential users for cycle regularity. There also are guidelines for monitoring users to determine continued method eligibility. This article explores the importance of these screening and monitoring procedures. A large existing dataset from a World Health Organization study of the Ovulation Method was used to estimate the theoretical probability of pregnancy using the Standard Days Method, with and without screening and monitoring. We used data from the efficacy study of the Standard Days Method to examine the effectiveness of current screening and monitoring procedures. Results suggest that current screening and monitoring procedures are useful in identifying women for whom the Standard Days Method is less effective. Strict adherence to these procedures is ideal, but even women who do not meet the cycle-regularity guidelines would have a relatively low probability of pregnancy.

Evaluation of the Efficacy of a Nonlatex Condom: Results from a Randomized, Controlled Clinical Trial

CONTEXT : To reduce unintended pregnancy and HIV infection, it is critical to develop reliable male condoms that will attract consumers who reject conventional latex condoms. METHODS : In a prospective clinical trial conducted in 1998-2000, 830 monogamous couples were randomized in equal numbers to use either a nonlatex condom or a commercial natural latex condom for six months as their only method of birth control. Couples completed detailed reports for the first five condom uses and recorded intercourse and condom use in coital diaries. Pregnancy rates associated with typical and consistent condom use were calculated using life-table analysis. Rates of clinical failure (condom breakage or slippage) were determined for the first five condom uses. RESULTS : During the first five uses, the nonlatex condom had a higher frequency of breakage or slippage during intercourse or withdrawal (4.0%) than latex condoms (1.3%); the breakage rate for the nonlatex condom was about eight times that of latex condoms. The six-cycle typical-use pregnancy rate did not differ significantly between users of non-latex (10.8%) and latex condoms (6.4%). The six-cycle consistent-use pregnancy rate was higher for nonlatex condom users than for latex condom users (4.9% vs. 1.0%). CONCLUSIONS : The data present strong indirect support for public health messages that promote the use of latex condoms and, for individuals who cannot or are unwilling to use latex condoms, the use of nonlatex condoms for prevention of pregnancy and disease.

Measuring contraceptive effectiveness: A conceptual framework

We present a conceptual model that outlines the four measures of how well a contraceptive method works: 1) efficacy, 2) effectiveness, 3) perfect-use pregnancy rate, and 4) typical-use pregnancy rate. Moreover, we illustrate how four variables influence these measures: 1) capacity to conceive, 2) frequency and timing of intercourse, 3) degree of compliance, and 4) inherent protection of the method. Because of inter-individual as well as intra-individual variability of the first three variables, generalizing results from a contraceptive clinical trial to other populations is problematic. There is a hierarchy of generalizability of the four outcome measures, with the typical-use pregnancy rate the least generalizable but the easiest to measure, and efficacy the most generalizable but the most difficult to measure. These four variables should be considered in the design and analysis of future contraceptive clinical trials. Finally, this article illustrates why the terms "pregnancy rate" and "failure rate" are not synonymous and why we recommend that the latter term not be used.

Standardized protocols for condom breakage and slippage trials: a proposal.

In the absence of well-controlled studies on the clinical effectiveness of condoms against pregnancy and sexually transmitted diseases, breakage and slippage data may provide the best indication of the protection offered by condom use. According to the recent literature, condom breakage rates range from 0% to 12%, with many US studies falling in the 2% to 5% range. Few studies have collected slippage data. In addition to discussing methodological issues associated with these studies, we propose a standardized protocol for future condom breakage and slippage trials and discuss how results may be used to estimate perfect-use and typical-use pregnancy rates.