A study of the vaginal contraceptive sponge used with and without the fertility awareness method

Fertility awareness-based methods for contraception: systematic review of randomized controlled trials

CONTEXT

Fertility awareness-based (FAB) methods of family planning estimate the fertile days of the menstrual cycle whether by observing fertility signs such as cervical secretions and basal body temperature or by monitoring cycle days. The efficacy and acceptability of these methods are unclear.

METHODS

We retrieved and analyzed all randomized controlled trials that examined any FAB method used for contraception.

RESULTS

Because of poor methods and reporting, pregnancy rates could not be determined. A trial in Colombia found similar numbers of pregnancies among women randomized to the ovulation and symptothermal methods, but a trial in Los Angeles observed more pregnancies in the group assigned to the ovulation method. In the two American trials, recruitment of participants was unexpectedly difficult. Continuation rates were poor.

CONCLUSION

Despite intensive training and ongoing support, most participants in these trials discontinued prematurely. The comparative efficacy of these methods remains unknown. However, with the ovulation and symptothermal methods, pregnancies appear to be common; method continuation rates are low.

Fertility awareness-based methods for contraception

BACKGROUND

"Fertility awareness-based methods" (FAB) of family planning "involve identification of the fertile days of the menstrual cycle, whether by observing fertility signs such as cervical secretions and basal body temperature, or by monitoring cycle days. FAB methods can be used in combination with abstinence or barrier methods during the fertile time" (WHO 2000). Several names have been used to describe this approach to contraception, including "rhythm," "natural family planning" and "periodic abstinence." Fertility awareness-based methods can be used with abstinence from sexual intercourse. Alternatively, they can be used with barrier contraceptives or withdrawal during presumed fertile times.

OBJECTIVES

We retrieved and analyzed all randomized controlled trials that examined any fertility awareness-based methods used for contraception.

SEARCH STRATEGY

We searched the computerized databases Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, POPLINE, EMBASE, and LILACS (each from its inception to January, 2004) for randomized controlled trials of fertility awareness-based methods. We examined the reference list of each trial as well as that of review articles.

SELECTION CRITERIA

We included all randomized controlled trials in any language that compared any fertility awareness-based methods for contraception with a placebo; another method, including an alternative fertility awareness-based method; or fertility awareness-based methods used in conjunction with another contraceptive.

DATA COLLECTION AND ANALYSIS

We assessed all titles and abstracts found for inclusion. We evaluated the methodological quality of the trials for potential biases by qualitatively assessing the study design; randomization method; allocation concealment; blinding; premature discontinuation rates; and loss to follow-up rates. Because of methodological weaknesses, we could not enter the trial results in RevMan, calculate measures of association, or aggregate data.

MAIN RESULTS

Because of poor methods and reporting, pregnancy rates could not be determined. A trial in Colombia found similar numbers of pregnancies among women randomized to the ovulation and symptothermal methods. In contrast, a companion trial in Los Angeles observed more pregnancies in the group assigned to the ovulation method. In the two U.S. trials, recruitment of participants was unexpectedly difficult; this aspect was not mentioned in the report from Colombia. Continuation rates were poor. In the two larger trials, most participants discontinued their assigned method before entering the observation phase of the trial.

REVIEWERS' CONCLUSIONS

The comparative efficacy of fertility awareness-based methods of contraception remains unknown. Despite intensive training and ongoing support, most participants in these trials discontinued prematurely. Contraceptive methods should be properly evaluated, preferably in randomized controlled trials, before adoption and dissemination.

Sponge versus diaphragm for contraception

BACKGROUND

The contraceptive vaginal sponge was developed as an alternative to the contraceptive diaphragm. The sponge, made of polyurethane impregnated with nonoxynol-9 (1g), releases 125 mg of the spermicide over 24 h of use. Unlike the diaphragm, the sponge can be used for more than one coital act within 24 h without the insertion of additional spermicide, and the sponge does not require fitting or a prescription from a physician. How the sponge compares with the diaphragm in terms of efficacy and continuation is not clear.

OBJECTIVES

To compare the efficacy and continuation rates of the sponge compared with the diaphragm (used with nonoxynol-9 as a spermicide). Our a priori hypothesis was that the sponge would have a higher failure rate and higher discontinuation rates than the diaphragm.

SEARCH STRATEGY

We searched the computerized databases MEDLINE, EMBASE, Popline, LILACS, and the Cochrane Controlled Trials Register. In addition, we searched the reference lists of all potentially relevant articles and book chapters. We also contacted investigators involved with both trials identified to seek other published or unpublished trials.

SELECTION CRITERIA

We included randomized controlled trials comparing the vaginal contraceptive sponge (Today; Collatex) with any diaphragm used with nonoxynol-9 to prevent pregnancy.

DATA COLLECTION AND ANALYSIS

We examined the studies identified through the literature searches for possible inclusion and evaluated their methodological quality using the Cochrane guidelines. We contacted an author involved with both published trials for supplementary information about randomization and allocation concealment. We entered data into RevMan 4.1 and calculated Peto odds ratios for overall pregnancy and 12-month discontinuation using numbers of women as the denominator. We also abstracted 12-month cumulative life-table ratios for these same outcomes, but were unable to aggregate these data.

MAIN RESULTS

The sponge was statistically significantly less effective in both trials in preventing overall pregnancy than was the diaphragm. The 12-month cumulative life-table termination rates per 100 women for overall pregnancy were 17.4 for the sponge versus 12.8 for the diaphragm in the larger U.S. trial and 24.5 for the sponge and 10.9 for the diaphragm in the U.K. trial. Similarly, discontinuation rates at 12 months were higher with the sponge than with the diaphragm (odds ratio 1.3; 95% CI 1.1-1.6). Allergic-type reactions were more common with the sponge in both trials, although the frequency of discontinuation for discomfort differed in the two trials.

REVIEWER'S CONCLUSIONS

The sponge was less effective than the diaphragm in preventing pregnancy. Discontinuation rates were higher at 12 months as well. Other randomized controlled trials will be needed to resolve the role of spermicides in preventing sexually transmitted infections or in causing adverse effects.

Sexual behavior of natural family planning users in Germany and its changes over time

For 10 years, a prospective study has been taking place in Germany to examine the use of natural family planning (NFP). As natural methods are behavioral methods, use-effectiveness, acceptability and continuation rates are very much influenced by patterns of sexual behavior. Therefore we performed an analysis of the sexual behavior of NFP users. Out of the data base of 1211 clients and 12,591 cycles we could identify a group of 300 women, all NFP beginners, with 5900 contraceptive cycles, who contributed at least 12 cycles with reliable recording of their sexual activity. Different groups were analyzed with methods of analysis of variance and regression models to find out significant differences in their sexual behavior with respect to sociodemographic structure and time of use. Nearly half of all the women systematically combine the fertility awareness part of NFP with other family planning methods. They use barriers in more than 60% of their cycles. The other half never or only in about 7% of their cycles use additional barrier methods. The latter show a clear decrease in barrier use in the course of time, whereas the frequent barrier users constantly combine the advantages of two family planning methods. Regarding the frequency of intercourse they are the sexually more active ones and show distinct sociodemographic characteristics. We could confirm the existence of three groups of NFP users, which differ significantly in their use of NFP as a family planning method. Despite these differences the low pregnancy rates indicate the conscious and risk-related sexual behavior of the group members.