Association between efficacy and body weight or body mass index for two low-dose oral contraceptives

Best Practice Contraception Care for Women with Obesity: A Review of Current Evidence

The prevalence of obesity among females of reproductive age is increasing globally. Access to the complete range of appropriate contraceptive options is essential for upholding the reproductive rights of this population group. People with obesity can experience stigma and discrimination when seeking healthcare, and despite limited evidence for provider bias in the context of contraception, awareness for its potential at an individual provider and health systems level is essential. While use of some hormonal contraceptives may be restricted due to increased health risks in people with obesity, some methods provide noncontraceptive benefits including a reduced risk of endometrial cancer and a reduction in heavy menstrual bleeding which are more prevalent among individuals with obesity. In addition to examining systems-based approaches which facilitate the provision of inclusive contraceptive care, including long-acting reversible contraceptives which require procedural considerations, this article reviews current evidence on method-specific advantages and disadvantages for people with obesity to guide practice and policy.

Contraceptive Options Following Gestational Diabetes: Current Perspectives

Gestational diabetes mellitus (GDM) complicates approximately 7% of pregnancies in the United States. Along with risk factors related to pregnancy, women with a history of GDM also have an increased risk of developing type 2 diabetes mellitus later in life. These women require special consideration when discussing contraception and other reproductive health issues. GDM carries a category 1 rating in the US Medical Eligibility Criteria for all contraceptive methods, which supports safety of the various methods but does not account for effectiveness. Contraceptive options differ in composition and mechanisms of action, and concerns have been raised about possible effects of contraception on metabolism. Clinical evidence is limited to suggest that hormonal contraception has significantly adverse effects on body weight, lipid, or glucose metabolism. In addition, the majority of evidence does not suggest a relationship between development of type 2 diabetes mellitus and use of hormonal contraception. Data are limited, so it is challenging to make a broad, general recommendation regarding contraception for women with a history of GDM. A woman’s history of GDM should be considered during contraceptive counseling. Discussion should focus on potential medical comorbidities and the implications of GDM on future health, with special consideration of issues including bone health, obesity, cardiovascular disease, and thrombosis risk. Providers must emphasize the importance of reliable, highly effective contraception for women with GDM, to optimize the timing of future pregnancies. This approach to comprehensive counseling will guide optimal decision-making on contraceptive use, lifestyle changes, and planning of subsequent pregnancies.

Medical Eligibility for Contraception in Women at Increased Risk

BACKGROUND

Most women of child-bearing age want a safe method of contraception. Numerous methods are available, with different modes of application. In situations involving particular risks, the selection of the right method poses a special challenge.

METHODS

Contraceptive methods for use in various situations with increased risk are presented in the light of a selective review of the literature, including the relevant current guidelines.

RESULTS

The current recommendations of the World Health Organization (WHO) can be used to determine whether any particular contraceptive method is applicable. In particular, the use of combined hormonal contraceptives may be contraindicated in the presence of certain risk factors, especially when there is an elevated risk of thromboembolism. Situations of increased risk include a genetic predisposition to thrombophilia, diabetes mellitus, age over 35, and nicotine abuse. Careful attention to the choice of an appropriate contraceptive agent is also necessary for women with hypertension, hepatic tumors, headache (including migraine), and epilepsy. For such patients, good alternatives include the use of a gestagen (=progesterone) single-agent preparation, an intrauterine device, or a pessary.

CONCLUSION

Meticulous history-taking and clinical examination are important components of contraceptive counseling that enable the identification of all potential risk factors. In situations of increased risk, decisions must be taken individually. Depending on the nature of the patient's underlying illness, interdisciplinary collaboration may be advisable. Even in situations of increased risk, an appropriated risk-benefit analysis should make it possible to find a suitable contraceptive method for any woman who needs one.

No. 329-Canadian Contraception Consensus Part 4 of 4 Chapter 9: Combined Hormonal Contraception

OBJECTIVE

To provide guidelines for health care providers on the use of contraceptive methods to prevent pregnancy and on the promotion of healthy sexuality.

OUTCOMES

Overall efficacy of cited contraceptive methods, assessing reduction in pregnancy rate, safety, and side effects; the effect of cited contraceptive methods on sexual health and general well-being; and the availability of cited contraceptive methods in Canada.

EVIDENCE

Medline and the Cochrane Database were searched for articles in English on subjects related to contraception, sexuality, and sexual health from January 1994 to December 2015 in order to update the Canadian Contraception Consensus published February-April 2004. Relevant Canadian government publications and position papers from appropriate health and family planning organizations were also reviewed.

VALUES

The quality of the evidence is rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care. Recommendations for practice are ranked according to the method described in this report.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Hormonal contraception and obesity

The rising rate of overweight and obesity is a public health crisis in the United States and increasingly around the globe. Rates of contraceptive use are similar among women of all weights, but because contraceptive development studies historically excluded women over 130% of ideal body weight, patients and providers have a gap in understanding of contraceptive efficacy for obese and overweight women. Because of a range of drug metabolism alterations in obesity, there is biologic plausibility for changes in hormonal contraception effectiveness in obese women. However, these pharmacokinetic changes are not linearly related to body mass index or weight, and it is unknown what degree of obesity begins to affect pharmacokinetic or pharmacodynamics processes. Overall, most studies of higher quality do not demonstrate a difference in oral contraceptive pill effectiveness in obese compared with non-obese women. However, data are scant for women in the highest categories of obesity, and differences by progestin type are incompletely understood. Effectiveness of most non-oral contraceptives does not seem to be compromised in obesity. Exceptions to this include the combined hormonal patch and oral levonorgestrel emergency contraception, which may have lower rates of effectiveness in obese women. The purpose of this review is to summarize evidence on contraceptive use in women with obesity, including differences in steroid hormone metabolism, contraceptive effectiveness, and safety, compared with women of normal weight or body mass index using the same methods.

Hormonal contraceptives for contraception in overweight or obese women

BACKGROUND

Obesity has reached epidemic proportions around the world. Effectiveness of hormonal contraceptives may be related to metabolic changes in obesity or to greater body mass or body fat. Hormonal contraceptives include oral contraceptives (OCs), injectables, implants, hormonal intrauterine contraception (IUC), the transdermal patch, and the vaginal ring. Given the prevalence of overweight and obesity, the public health impact of any effect on contraceptive efficacy could be substantial.

OBJECTIVES

To examine the effectiveness of hormonal contraceptives in preventing pregnancy among women who are overweight or obese versus women with a lower body mass index (BMI) or weight.

SEARCH METHODS

Until 4 August 2016, we searched for studies in PubMed (MEDLINE), CENTRAL, POPLINE, Web of Science, ClinicalTrials.gov, and ICTRP. We examined reference lists of pertinent articles to identify other studies. For the initial review, we wrote to investigators to find additional published or unpublished studies.

SELECTION CRITERIA

All study designs were eligible. The study could have examined any type of hormonal contraceptive. Reports had to contain information on the specific contraceptive methods used. The primary outcome was pregnancy. Overweight or obese women must have been identified by an analysis cutoff for weight or BMI (kg/m(2)).

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data. One entered the data into RevMan and a second verified accuracy. The main comparisons were between overweight or obese women and women of lower weight or BMI. We examined the quality of evidence using the Newcastle-Ottawa Quality Assessment Scale. Where available, we included life-table rates. We also used unadjusted pregnancy rates, relative risk (RR), or rate ratio when those were the only results provided. For dichotomous variables, we computed an odds ratio with 95% confidence interval (CI).

MAIN RESULTS

With 8 studies added in this update, 17 met our inclusion criteria and had a total of 63,813 women. We focus here on 12 studies that provided high, moderate, or low quality evidence. Most did not show a higher pregnancy risk among overweight or obese women. Of five COC studies, two found BMI to be associated with pregnancy but in different directions. With an OC containing norethindrone acetate and ethinyl estradiol (EE), pregnancy risk was higher for overweight women, i.e. with BMI ≥ 25 versus those with BMI < 25 (reported relative risk 2.49, 95% CI 1.01 to 6.13). In contrast, a trial using an OC with levonorgestrel and EE reported a Pearl Index of 0 for obese women (BMI ≥ 30) versus 5.59 for nonobese women (BMI < 30). The same trial tested a transdermal patch containing levonorgestrel and EE. Within the patch group, obese women in the "treatment-compliant" subgroup had a higher reported Pearl Index than nonobese women (4.63 versus 2.15). Of five implant studies, two that examined the six-capsule levonorgestrel implant showed differences in pregnancy by weight. One study showed higher weight was associated with higher pregnancy rate in years 6 and 7 combined (reported P < 0.05). In the other, pregnancy rates differed in year 5 among the lower weight groups only (reported P < 0.01) and did not involve women weighing 70 kg or more.Analysis of data from other contraceptive methods indicated no association of pregnancy with overweight or obesity. These included depot medroxyprogesterone acetate (subcutaneous), levonorgestrel IUC, the two-rod levonorgestrel implant, and the etonogestrel implant.

AUTHORS' CONCLUSIONS

The evidence generally did not indicate an association between higher BMI or weight and effectiveness of hormonal contraceptives. However, we found few studies for most contraceptive methods. Studies using BMI, rather than weight alone, can provide information about whether body composition is related to contraceptive effectiveness. The contraceptive methods examined here are among the most effective when used according to the recommended regimen.We considered the overall quality of evidence to be low for the objectives of this review. More recent reports provided evidence of varying quality, while the quality was generally low for older studies. For many trials the quality would be higher for their original purpose rather than the non-randomized comparisons here. Investigators should consider adjusting for potential confounding related to BMI or contraceptive effectiveness. Newer studies included a greater proportion of overweight or obese women, which helps in examining effectiveness and side effects of hormonal contraceptives within those groups.

The influence of partnership on contraceptive use among HIV-infected women accessing antiretroviral therapy in rural Uganda

OBJECTIVE

The objective was to determine individual and dyadic factors associated with effective contraceptive use among human immunodeficiency virus (HIV)-infected women accessing antiretroviral therapy (ART) in rural Uganda.

STUDY DESIGN

HIV-infected women enrolled in the Uganda AIDS Rural Treatment Outcomes cohort completed questionnaires (detailing sociobehavioral characteristics, sexual and reproductive history, contraceptive use, fertility desires) and phlebotomy (October 2011-March 2013). We describe prevalence of effective contraceptive use (i.e., consistent condom use and/or oral contraceptives, injectable hormonal contraception, intrauterine device, female sterilization) in the previous 6 months among sexually active, nonpregnant women (18-40 years). We assessed covariates of contraceptive use using multivariable logistic regression.

RESULTS

A total of 362 women (median values: age 30 years, CD4 count 397 cells/mm(3), 4.0 years since ART initiation) were included. Among 284 sexually active women, 50% did not desire a(nother) child, and 51% had a seroconcordant partner. Forty-five percent (n=127) reported effective contraceptive use, of whom 57% (n=72) used condoms, 42% (n=53) injectables, 12% (n=15) oral contraceptives and 11% (n=14) other effective methods. Dual contraception was reported by 6% (n=8). Only "partnership fertility desire" was independently associated with contraceptive use; women who reported that neither partner desired a child had significantly increased odds of contraceptive use (adjusted odds ratio: 2.40, 95% confidence interval: 1.07-5.35) compared with women in partnerships where at least one partner desired a child.

CONCLUSIONS

Less than half of sexually active HIV-infected women accessing ART used effective contraception, of which 44% (n=56) relied exclusively on male condoms, highlighting a continued need to expand access to a wider range of longer-acting female-controlled contraceptive methods. Association with partnership fertility desire underscores the need to include men in reproductive health programming.

IMPLICATIONS STATEMENT

Less than half of sexually active HIV-infected women accessing ART in rural Uganda reported using effective contraception, of whom 44% relied exclusively on the male condom. These findings highlight the need to expand access to a wider range of longer-acting, female-controlled contraceptive methods for women seeking to limit or space pregnancies. Use of contraception was more likely when both the male and female partner expressed concordant desires to limit future fertility, emphasizing the importance of engaging men in reproductive health programming.

Hormonal contraceptives for contraception in overweight or obese women

BACKGROUND

Obesity has reached epidemic proportions around the world. Effectiveness of hormonal contraceptives may be related to metabolic changes in obesity or greater body mass or body fat. Hormonal contraceptives mainly include oral contraceptives, injectables and implants, the transdermal patch, and the vaginal ring. We systematically reviewed the evidence on the effectiveness of hormonal contraceptives among overweight and obese women.

OBJECTIVES

To examine the effectiveness of hormonal contraceptives in preventing unplanned pregnancies among women who are overweight or obese versus women of lower weight or body mass index (BMI).

SEARCH METHODS

Through January 2013, we searched MEDLINE, CENTRAL, POPLINE, ClinicalTrials.gov, and ICTRP. The previous search also included EMBASE. We contacted investigators to identify other trials.

SELECTION CRITERIA

All study designs were eligible. Any type of hormonal contraceptive could have been examined. Reports had to contain information on the specific contraceptive method(s). The primary outcome was pregnancy. Overweight or obese women must have been identified by an analysis cutoff for weight or BMI (kg/m(2)).

DATA COLLECTION AND ANALYSIS

Data were abstracted by two authors. Life-table rates were included where available. For dichotomous variables, we computed an odds ratio with 95% confidence interval (CI). We used reported pregnancy rates or relative risk (RR) when those were the only results provided. The main comparisons were between overweight or obese women and women of lower weight or BMI. We assessed the quality of evidence for this review.

MAIN RESULTS

We found nine reports with data from 13 trials that included a total of 49,712 women. Five reports from 2002 to 2012 compared BMI groups; of those, one reported a higher pregnancy risk for overweight or obese women. In that trial, women assigned to an oral contraceptive containing norethindrone acetate 1.0 mg plus EE 20 µg and having a BMI at least 25 had greater pregnancy risk compared to those with BMI less than 25 (reported RR 2.49; 95% CI 1.01 to 6.13). The comparisons reported in the other four studies were not significantly different for pregnancy. These included studies of a combined oral contraceptive (COC), a transdermal patch, an implant, and an injectable. The COC study showed no trend by BMI or weight. With the transdermal patch, body weight was associated with pregnancy (reported P < 0.001) but BMI was not. The implant study had one pregnancy and the injectable study reported no pregnancies.Four studies from the 1990s used weight alone rather than BMI. Results were mixed. Studies of a vaginal ring (never marketed) and a six-rod implant showed higher pregnancy rates for women weighing at least 70 kg versus those weighing less than 70 kg (reported P values: 0.0013 and < 0.05, respectively). However, two implant studies showed no trend by body weight.

AUTHORS' CONCLUSIONS

The evidence did not generally show an association of BMI with effectiveness of hormonal contraceptives. However, the evidence was limited for any individual contraceptive method. Studies using BMI (rather than weight alone) can provide more information about whether body composition is related to contraceptive effectiveness. The efficacy of subdermal implants and injectable contraceptives may be unaffected by body mass. The contraceptive methods examined here are among the most effective when the recommended regimen is followed.The overall quality of evidence was low for this review. More recent reports provided moderate quality evidence, while the older studies provided evidence of low or very low quality for our purposes. Investigators should consider adjusting for potential confounding related to BMI. Trials should be designed to include sufficient numbers of overweight or obese women to adequately examine effectiveness and side effects of hormonal contraceptives within those groups.

Maternal obesity and pre-pregnancy folic acid supplementation

OBJECTIVE

The purpose of this nested cohort study was to compare the rate of pre-pregnancy supplementation in obese women with that of women with a normal BMI.

METHODS

Pregnant women were enrolled at their convenience in a large university hospital. Weight and height were measured in the first trimester and BMI categorised.

RESULTS

Of the 288 women, 35.1% were in the normal, 29.5% in the overweight and 35.4% in the obese BMI categories. Only 45.1% (n = 46) of the obese women took pre-pregnancy folic acid compared with 60.4% (n = 61) of women with a normal BMI (p < 0.03). The lower incidence of folic acid supplementation in obese women was associated with an unplanned pregnancy in 36.3% of women compared with 22.8% in the normal BMI category (p < 0.04).

CONCLUSIONS

Obese women should take folate supplements whether they are planning to conceive or not.

Ovarian activity in obese and nonobese women treated with three transdermal contraceptive patches delivering three different doses of ethinyl estradiol and levonorgestrel

BACKGROUND

The effect of obesity on ovarian follicular suppression in women using low-estrogen dose contraceptive patches has not been determined.

STUDY DESIGN

A Phase II, parallel-group, multicenter, three-cycle study evaluated three patches containing different ethinyl estradiol (EE) and levonorgestrel (LNG) doses. Serum levels of EE, LNG, sex hormone-binding globulin and progesterone were compared in 41 obese [body mass index (BMI) ≥30] and 75 nonobese (BMI <30) women.

RESULTS

Suppression of ovulation during the luteal phase was dose dependent, with the highest dose (AG200-15) preventing progesterone increases in all women (cycles 2-3). In the follicular phase, the lowest-dose patch had the highest rate of increased progesterone in nonobese subjects. Progesterone levels ≥3.0 ng/mL in the follicular phase were more common in obese than nonobese women.

CONCLUSIONS

AG200-15 suppresses ovulation in obese and nonobese women. All three patches found increased progesterone in the follicular phase, albeit more in obese versus nonobese women.

A chewable low-dose oral contraceptive: a new birth control option?

A new chewable combined oral contraceptive pill containing ethinyl estradiol (EE) 0.025 mg and norethindrone (NE) 0.8 mg in a 24/4 regimen was approved for marketing in December 2010. Each of the four inactive tablets contains 75 mg ferrous fumarate, which has no therapeutic benefit. The tablet can be taken with food but not water as this affects the absorption of EE. The Pearl index based on intention to treat women aged 18-35 years has been reported at 2.01 (confidence interval [CI] 1.21, 3.14) and for the whole population 1.65 (CI 1.01, 2.55). The effect of a body mass index of >35 was not studied. Regular withdrawal bleeding occurred for 78.6% of women in Cycle 1, but by Cycle 13 almost half the women failed to have a withdrawal bleed. This new formulation provides an intermediate dose of an EE/NE combination that will be useful for women experiencing breakthrough bleeding on the lower-dose EE/NE pill. The convenience of a low-dose pill, which can be chewed without the need for water, will be useful to enable women who have forgotten a pill to take one whenever they remember, provided they carry it with them. The advantage of a 24/4 regimen is better suppression of follicular development in the pill-free interval and may be beneficial for women who experience menstrual cycle-related problems, such as heavy bleeding or dysmenorrhea.

Contraceptive choices of overweight and obese women in a publically funded hospital: possible clinical implications

BACKGROUND

Despite the growing obesity epidemic in the United States, family planning for overweight and obese women has been understudied. The aim of this study was to describe the contraception methods selected by normal weight, overweight and obese women.

STUDY DESIGN

We retrospectively reviewed 7262 charts of women who underwent first trimester surgical termination of pregnancy at the John H. Stroger, Jr. Hospital of Cook County between January 1, 2008, and January 1, 2010. We analyzed the relationship between body mass index (BMI) and choice of contraceptive method, after adjusting for age, race, smoking and level of education.

RESULTS

When compared to patients with BMI <25 kg/m², overweight (BMI 25-29.9 kg/m²) and obese patients (BMI ≥30 kg/m²) were more likely to select the intrauterine device (OR 1.3, 95% CI 1.28-1.32 for overweight; OR 1.6, 95% CI 1.59-1.61 for obese), contraceptive ring (OR 1.4, 95% CI 1.28-1.52 for overweight; OR 1.6, 95% CI 1.57-1.63 for obese) and tubal ligation (OR 1.5 95% CI 1.44-1.62 for overweight; OR 2.9, 95% CI 2.79-3.01 for obese). They were less likely to choose injectable contraception (OR 0.7, 95% CI 0.59-0.81 for overweight; OR 0.52, 95% CI 0.48-0.56 for obese). There was no relationship between BMI and choice of condoms, oral contraceptive pills and implantable methods.

CONCLUSION

In our population, the contraceptive choices of overweight and obese women differed from those of normal weight women. These differences in contraceptive selection are important to recognize in light of the potential effect of BMI on the safety and efficacy of different contraceptive methods. Further research is needed to evaluate the contraceptive preferences, risks and benefits for overweight and obese women.

Contraceptive considerations in overweight teens

PURPOSE OF REVIEW

The purpose of this review is to explore the efficacy and safety of contraceptives in overweight adolescents.

RECENT FINDINGS

There are few studies exploring hormonal contraceptive efficacy and safety in overweight and obese adults and almost none addressing these issues in adolescents. Luckily for teens, in terms of safety, many of the comorbidities associated with obesity are yet to transpire and their options for contraception remain relatively unrestricted. Studies of the combined oral contraceptive pill and patch in adults suggest that efficacy may be decreased in overweight adolescents. There is no evidence to suggest that the efficacy of the contraceptive implant or intrauterine device (IUD) is decreased in overweight adolescents. Indeed, these long-acting reversible methods will be the best choice for many adolescents because of their high efficacy. Although the literature is not definitive, there is probably a subset of adolescents who are susceptible to weight gain with use of depot medroxyprogesterone acetate.

SUMMARY

Although there is little research regarding contraceptive efficacy in overweight adolescents, IUDs and implants will be the best methods for many adolescents because of their high efficacy, reversibility, and safety.

Body weight does not impact pregnancy rates during use of a low-dose extended-regimen 91-day oral contraceptive

BACKGROUND

This study evaluated the impact of weight on efficacy during use of an extended oral contraceptive (OC).

STUDY DESIGN

Data were from a Phase 3 clinical trial evaluating the efficacy of a low-dose 91-day extended regimen of 100 mcg levonorgestrel/20 mcg ethinyl estradiol (LNG/EE; 84 days)+10 mcg EE (7 days) for the prevention of pregnancy. Crude pregnancy rates were calculated for weight and body mass index (BMI) deciles.

RESULTS

Of the 1736 women in this analysis, 878 (50.6%) had a BMI greater than 25 kg/m2, and 770 (44.4%) were heavier than 70 kg. Pregnancies occurred in 36 women. Crude pregnancy rates were similar across weight and BMI deciles, with no discernable differences observed between deciles using either classification criterion.

CONCLUSIONS

No evidence of any reduction in the level of contraceptive efficacy was observed with this low-dose extended OC regimen in overweight and obese women.

Types of progestogens in combined oral contraception: effectiveness and side-effects

BACKGROUND

The progestogen component of combined oral contraceptives (COC) has undergone changes since it was first recognised that it's chemical structure could influence the spectrum of minor adverse and beneficial effects. The major determinants of effectiveness are compliance and continuation which may be influenced by cycle control and common side effects. The rationale of this review is to provide a systematic comparison of COCs containing the progestogens currently in use worldwide.

OBJECTIVES

To compare currently available low-dose COCs containing ethinyl estradiol and different progestogens in terms of contraceptive effectiveness, cycle control, side effects and continuation rates.

SEARCH STRATEGY

A search of PubMed, LILACS, EMBASE, Popline, CINAHL and the Cochrane Central Register of Controlled Trials databases was conducted in September 2010 to update the 2004 review.

SELECTION CRITERIA

Randomised trials reporting clinical outcomes were considered for inclusion. We excluded studies comparing monophasic with multiphasic pills, crossover trials, trials in which the difference in total content of ethinyl estradiol between preparations exceeded 105 µg per cycle and those comparing continuous dosing regimens.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed methodological quality, applied inclusion criteria and extracted data.

MAIN RESULTS

Thirty trials with a total of 13,923 participants were included, generating 16 comparisons. Overall the quality of trials was low. Only four trials were double-blind. At least twenty-three trials were sponsored by pharmaceutical companies. There was less discontinuation with second-generation compared with first-generation monophasic progestogens (3 trials, 2,709 women, Relative Risk (RR) 0.76, 95% Confidence Interval (CI) 0.67-0.86); this remained significant when only double-blind trials were considered (812 women, RR 0.79, 95% CI 0.66-0.94).Women using monophasic COC's containing third-generation progestogens were less likely to discontinue than the second-generation group (3 trials, 1,815 women, RR 0.77, 95% CI 0.60-0.98) but this was not significant when only double-blind trials were considered (RR 0.79, 95% CI 0.50-1.26]. Women in the third-generation group experienced less intermenstrual bleeding than the second-generation group (one double-blind trial, 456 women, RR 0.71, 95% CI 0.55-0.91).Compared to desogestrel (DSG), women in the drospirenone (DRSP) group were more likely to complain of breast tenderness (5 trials, 4,258 women, RR 1.39, 95% CI 1.04-1.86) and nausea (6 trials, 4,701 women, RR 1.46, 95% CI 0.96-2.21].Pregnancy rates overall were comparable but the trials had insufficient power to find potentially important differences.

AUTHORS' CONCLUSIONS

Women using COCs containing second-generation progestogens may be less likely to discontinue than those using COCs containing first-generation progestogens. Based on one small double-blind trial, third-generation progestogens may be preferable to second-generation preparations with regard to bleeding patterns but further evidence is needed. Without blinding as to treatment group, comparisons between the various "generations" of progestogens used in COCs cannot be made. Until this widespread methodological flaw is overcome in better trials conducted according to CONSORT guidelines and internationally accepted definitions, no further conclusions can be drawn.

Hormonal contraceptives for contraception in overweight or obese women

BACKGROUND

Obesity has reached epidemic proportions around the world. Metabolic changes in obesity and greater body mass may lead to reduced effectiveness of hormonal contraceptives, such as the skin patch, vaginal ring, implants, and injectables. We systematically reviewed the evidence on the effectiveness of hormonal contraceptives among overweight and obese women.

OBJECTIVES

To examine the effectiveness of hormonal contraceptives in preventing unplanned pregnancies among women who are overweight or obese versus women of lower weight or body mass index (BMI).

SEARCH STRATEGY

We searched MEDLINE, CENTRAL, POPLINE, EMBASE, ClinicalTrials.gov, and ICTRP. We also contacted investigators to identify other trials.

SELECTION CRITERIA

All study designs were eligible. Any type of hormonal contraceptive could have been examined. The primary outcome was pregnancy. Overweight or obese women must have been identified by an analysis cutoff for weight or BMI (kg/m).

DATA COLLECTION AND ANALYSIS

Data were abstracted by two authors; life-table rates were included where available. For dichotomous variables, we computed an odds ratio with 95% (CI). The main comparisons were between overweight or obese women of lower weight or BMI.

MAIN RESULTS

We found 7 reports with data from 11 trials that included 39,531 women. One of three studies using BMI found a higher pregnancy risk for overweight or obese women. In the trial of two combination oral contraceptives, women with BMI >=25 had greater pregnancy risk compared to those with BMI <25 (OR 1.91; 95% CI 1.01 to 3.61). Among skin patch users, body weight was associated with pregnancy (reported P<.001) but BMI was not. Studies of a vaginal ring (never marketed) and a six-rod implant showed higher pregnancy rates for women weighing >=70 kg versus those weighing <70 kg (reported P values: 0.0013 and <0.05, respectively). However, two implant studies showed no trend by body weight, and trials of an injectable had no pregnancies.

AUTHORS' CONCLUSION

Body weight addresses overall body size, while BMI generally reflects the amount of fat. Only one of three studies using BMI found a higher pregnancy risk for overweight women. The efficacy of implants and injectable contraceptives may be unaffected by body mass. The field could use trials of contraceptive methods with groups stratified by BMI. The current evidence on effectiveness by BMI is limited. However, the contraceptive methods examined here are still among the most effective when recommended regimen is followed.

Hormonal contraceptives for contraception in overweight or obese women

BACKGROUND

Obesity has reached epidemic proportions around the world. Metabolic changes in obesity and greater body mass may lead to reduced effectiveness of hormonal contraceptives, such as the skin patch, vaginal ring, implants, and injectables. We systematically reviewed the evidence on the effectiveness of hormonal contraceptives among overweight and obese women.

OBJECTIVES

To examine the effectiveness of hormonal contraceptives in preventing unplanned pregnancies among women who are overweight or obese versus women of lower weight or body mass index (BMI).

SEARCH STRATEGY

We searched MEDLINE, CENTRAL, POPLINE, EMBASE, ClinicalTrials.gov, and ICTRP. We also contacted investigators to identify other trials.

SELECTION CRITERIA

All study designs were eligible. Any type of hormonal contraceptive could have been examined. The primary outcome was pregnancy. Overweight or obese women must have been identified by an analysis cutoff for weight or BMI (kg/m(2)).

DATA COLLECTION AND ANALYSIS

Data were abstracted by two authors; life-table rates were included where available. For dichotomous variables, we computed an odds ratio with 95% confidence interval. The main comparisons were between overweight or obese women and women of lower weight or BMI.

MAIN RESULTS

We found 7 reports with data from 11 trials that included 39,531 women. One of three studies using BMI found a higher pregnancy risk for overweight or obese women. In the trial of two combination oral contraceptives, women with BMI >= 25 had greater pregnancy risk compared to those with BMI < 25 (OR 1.91; 95% CI 1.01 to 3.61). Among skin patch users, body weight was associated with pregnancy (reported P < 0.001) but BMI was not. Studies of a vaginal ring (never marketed) and a six-rod implant showed higher pregnancy rates for women weighing >= 70 kg versus those weighing < 70 kg (reported P values: 0.0013 and < 0.05, respectively). However, two implant studies showed no trend by body weight, and trials of an injectable had no pregnancies.

AUTHORS' CONCLUSIONS

Body weight addresses overall body size, while BMI generally reflects the amount of fat. Only one of three studies using BMI found a higher pregnancy risk for overweight women. The efficacy of implants and injectable contraceptives may be unaffected by body mass. The field could use trials of contraceptive methods with groups stratified by BMI. The current evidence on effectiveness by BMI is limited. However, the contraceptive methods examined here are still among the most effective when the recommended regimen is followed.

Why do women experience untimed pregnancies? A review of contraceptive failure rates

Contraceptive failure contributes to a substantial proportion of unintended pregnancy, particularly in the developed world. A number of socio-demographic factors seem to impact on the risk of a woman experiencing contraceptive failure. Many of the issues exist across cultural boundaries and are complex to address. In discussing the failure rates for individual contraceptive methods, this article will highlight the advantage of improving uptake of long-acting reversible methods of contraception which have a high efficacy and are less user-dependent than many of the other available methods.