Effect of obesity on the effectiveness of hormonal contraceptives: an individual participant data meta-analysis

An overview of contraception in women with obesity

The use of safe and effective contraception is essential for preventing unplanned pregnancy in women of all body sizes. When counseling women with obesity about contraception, it is important to consider the pharmacokinetic alterations of obesity on various modern contraceptive methods. However, evidence is reassuring that most contraceptive methods are safe and effective in women with obesity. Individual countries and the World Health Organization have published Medical Eligibility Criteria to guide contraceptive selection in women with medical issues including obesity. When choosing contraception, specific risks of the method relative to any underlying medical disorders must also be balanced against the risks of unintended pregnancy in this group.

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.

[Contraception in adolescents with obesity and diabetes mellitus]

Today most adolescents have their first sexual experience at the age of 15-19. However, only 44% of girls and young women (15-24 years old) report about contraception at that moment. A decision on pregnancy in adolescence is a difficult choice and any scenario may cause serious medical and social problems. Complications after an artificial abortion have a negative impact on a woman's fertility. Diabetes mellitus type 1 and arterial hypertension accompanied with obesity within the metabolic syndrome are defined by the World Health Organization (WHO) as diseases, which increase risk of an unplanned pregnancy. The article consoders problems of interaction of a doctor and a teenage girl with endocrinopathy, when discussing her sexual health, the analysis of the literature reflecting the influence of contraception on the course of the underlying pathology is presented. The authors formed a list of drugs acceptable for use in diabetes and obesity based on assessment of risks and preferences from the use of different methods of fertility control. The work contains information about the procedure of starting contraception, the rules of future dynamic monitoring of the patient.

Hormonal Contraception: Systemic Estrogen and Progestin Preparations

Combined hormonal contraception (CHC) are short-acting, reversible methods containing both estrogen and progestin. Available CHC methods include combined oral contraceptives, transdermal patches, and vaginal rings. The combined oral contraceptive remains the most commonly used contraceptive method in the United States. The general principles of CHC will be reviewed, including mechanism of action and effectiveness. Unless otherwise stated, these principles apply to all CHCs. When discussing clinical studies and specific considerations related only to pills, patches, or rings, the method(s) will be specified. Words that specify sex are used when discussing studies in which sex was specified.

Variability in Contraceptive Clinical Trial Design and the Challenges in Making Comparisons Across Trials

Clinical trials of contraceptives have often differed in their study designs, making cross-trial comparisons difficult. This brief report outlines some of the technical design features that can vary from trial to trial. For example, the overall number of menstrual cycles in a study has substantial impact on the final efficacy determination; however, the rules related to qualifying cycles can differ based on the length of the study and the statistical analysis plan. In two commonly used methods of calculating efficacy, the Pearl Index and the time-to-event analysis, inclusion of fewer menstrual cycles results in higher calculated failure rates. Statistical analysis plans for contraceptive trials have sometimes excluded menstrual cycles because of an absence of documented vaginal intercourse and the concomitant use of another birth control method. Other design features that have varied between contraceptive trials relate to body mass index inclusion/exclusion criteria and the definition of "on-treatment" pregnancy. In addition, study designs of non-hormonal products can differ from those of hormonal products in their length and rules for qualifying cycles. The Draft Guidance for Hormonal Contraception, published in 2019 by the US Food and Drug Administration (FDA), will hopefully lead to more uniform trial design in the future, particularly for hormonal products. In the meantime, health care providers and patients should be aware of the nuances in trial design that make direct comparisons about relative efficacy challenging.

Determining the Exposure Threshold for Levonorgestrel Efficacy Using an Integrated Model Based Meta-Analysis Approach

Combined oral contraceptive pills are the most commonly used hormonal contraceptives for the prevention of unintended pregnancies in United States. They consist of a progestin (e.g., levonorgestrel (LNG)) and an estrogen component, typically ethinyl estradiol (EE). In addition to adherence issues, drug-drug interactions (DDIs) and obesity (women with body mass index (BMI) ≥ 30 kg/m² ) are prime suspects for decreased LNG efficacy. Therefore, we developed an integrated physiologically-based pharmacokinetic modeling and model-based meta-analysis approach to determine LNG's efficacy threshold concentrations and to evaluate the impact of DDIs and obesity on the efficacy of LNG-containing hormonal contraceptives (HCs). Based on this approach, co-administration of strong CYP3A4 inducers and LNG-containing HCs (LNG150: LNG 150 µg + EE 30 µg and LNG100: LNG 100 µg + EE 20 µg) resulted in a predicted clinically relevant decrease of LNG plasma exposure (women with BMI < 25 kg/m² : 50-65%; obese women: 70-75%). Following administration of LNG150 or LNG100 in the presence of a CYP3A4 inducer, there was an increase in mean Pearl Index of 1.2-1.30 and 1.80-2.10, respectively, in women with BMI < 25 kg/m² (incidence rate ratios (IRRs): 1.7-2.2), whereas it ranged from 1.6-1.80 and 2.40-2.85 in obese women (IRR: 2.2-3.0), respectively. Our results suggest that the use of backup or alternate methods of contraception is not necessarily required for oral LNG + EE formulations except within circumstances of both obesity and strong CYP3A4 inducer concomitance following administration of LNG100.

Efficacy, safety, and tolerability of a levonorgestrel/ethinyl estradiol transdermal delivery system: Phase 3 clinical trial results

OBJECTIVE

To assess the contraceptive efficacy, safety, and tolerability of a contraceptive transdermal delivery system, (TDS; TWIRLA^Ⓡ) containing levonorgestrel (LNG) and ethinyl estradiol (EE).

STUDY DESIGN

This single-arm, open-label, multicenter, 1-year (13 cycle), phase 3 study enrolled sexually active women ≥18 years old at risk for pregnancy irrespective of body mass index (BMI). Women used patches in 28-day cycles (3 consecutive administrations of 7-day patches followed by 7 days off-treatment/patch-free week). We assessed contraceptive efficacy by the Pearl Index (PI) in women 18 to 35 years, excluding cycles without intercourse or when other contraceptive methods were used.

RESULTS

The study enrolled 2032 demographically diverse women in the US, of which 35.3% had a BMI ≥30 kg/m². In the primary efficacy analysis, the PI (95% confidence interval) was 5.8 (4.5-7.2) pregnancies per 100 woman-years. PIs trended higher as BMI increased; the PI was 4.3 (2.9-5.8) in women with BMI <30 kg/m² and 8.6 (5.8-11.5) in women with BMI ≥30 kg/m². Hormone-related treatment-emergent adverse events included nausea (4.1%) and headache (3.6%); 11% of women discontinued due to adverse events. Four women (all with BMIs ≥30 kg/m²) reported thromboembolic events considered related to treatment.

CONCLUSIONS

The low-dose LNG/EE TDS was effective in preventing pregnancy in a population of women representative of US demographics. Efficacy was reduced in women with BMI ≥30 kg/m². The TDS safety and tolerability profile was consistent with other similar dose combined hormonal contraceptives. Results of this phase 3 study supported the US Food and Drug Administration approval of TWIRLA^Ⓡ for prevention of pregnancy in women with BMI <30 kg/m².

IMPLICATIONS

TDS (120 µg/day levonorgestrel and 30 µg/day ethinyl estradiol) is an effective, low-dose transdermal contraceptive patch with favorable tolerability profile approved for prevention of pregnancy in women with BMI <30 kg/m². TDS has reduced effectiveness in women with BMI ≥30 kg/m².

Obesity and hormonal contraception: an overview and a clinician's practical guide

BACKGROUND

The growing prevalence of obesity among the fertile female population poses a considerable problem to contraceptive providers. Obese women, who are more at risk for venous thromboembolism and cardiovascular events due to their condition, might be at an even higher risk of developing thromboembolic events when on medical contraception. Combined hormonal contraceptives might be less effective in obese women and may lead to unacceptable metabolic side effects for this population. In addition, the lack of safety data for weight loss drugs and the higher risk for complications during and after pregnancy require a close surveillance of the fertility status of obese patients.

OBJECTIVE

The aim of this narrative review is to summarize the available medical contraceptive options and to give the readers a practical guidance for a wise contraceptive choice with regards to obesity.

METHODS

A general literature review of peer-reviewed publications on the topic "obesity and contraception" was performed using the PubMed database.

RESULTS

Nowadays, there are many useful tools that help clinicians in choosing among the wide range of therapeutic possibilities, such as the World Health Organization (WHO) Medical Eligibility Criteria for contraceptive use. Furthermore, the great diversity of hormonal contraceptive formulations (combined hormonal formulations; progestin-only methods) and active substances (different estrogens and progestins) allow physicians to tailor therapies to patients' clinical peculiarities.

CONCLUSION

Long-acting reversible contraceptives [progestin-only implants, levonorgestrel-intra-uterine devices (IUDs) and copper IUDs] and progestin-only methods in general are excellent options for many categories of patients, including obese ones.

LEVEL OF EVIDENCE

V, narrative review.

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.

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 contraceptive use in Australian women: Who is using what?

BACKGROUND

In Australia many hormonal contraceptives are not Pharmaceutical Benefits Scheme (PBS) supported, hence the use of different formulations have not been quantified.

OBJECTIVES

To document the use of hormonal contraceptives and factors associated with their use.

MATERIALS AND METHODS

Cross-sectional, online questionnaire-based study of 6986 Australian women, aged 18-39 years, recruited by email invitation from two large, representative databases. Main outcome measures were the prevalence of use of hormonal contraceptives and associated socio-demographic characteristics.

RESULTS

Of the 6600 potential hormone contraceptive users, 43.2% were current users. Most (63.6%) reported using a combined oral contraceptive (COC) of which 30.9% were non-PBS-supported anti-androgenic progestin-containing COCs. Use of long-acting reversible contraceptives (LARC) or an injectable contraceptive was reported by 26.8%. Education beyond secondary school, being Australian born, rural residency, normal body mass index, age <25 years and nulliparity were significantly associated with hormonal contraceptive use. Women who reported polycystic ovary syndrome or acne were more likely to be taking a third or fourth generation COC (P < 0.0001) and endometriosis was significantly associated with intrauterine system (IUS) use. Third or fourth generation COC use was reported by 12.1% of obese, current smokers.

CONCLUSION

An estimated one-third of Australian women aged 18-39 are taking a non-PBS-supported anti-androgenic progestin COC, highlighting inequity in access to COC options. That hormonal contraceptive use is higher in rural areas is a novel finding and the proportion of LARC or injectable use suggests that uptake in Australia is higher than previously reported.

A Systematic Approach for Post Hoc Subgroup Analyses With Applications in Clinical Case Studies

BACKGROUND

The analysis of subgroups in clinical trials is essential to assess differences in treatment effects for distinct patient clusters, that is, to detect patients with greater treatment benefit or patients where the treatment seems to be ineffective.

METHODS

The software application subscreen (R package) has been developed to analyze the population of clinical trials in minute detail. The aim was to efficiently calculate point estimates (eg, hazard ratios) for multiple subgroups to identify groups that potentially differ from the overall trial result. The approach intentionally avoids inferential statistics such as P values or confidence intervals but intends to encourage discussions enriched with external evidence (eg, from other studies) about the exploratory results, which can be accompanied by further statistical methods in subsequent analyses. The subscreen application was applied to 2 clinical study data sets and used in a simulation study to demonstrate its usefulness.

RESULTS

The visualization of numerous combined subgroups illustrates the homogeneity or heterogeneity of potentially all subgroup estimates with the overall result. With this, the application leads to more targeted planning of future trials.

CONCLUSION

This described approach supports the current trend and requirements for the investigation of subgroup effects as discussed in the EMA draft guidance for subgroup analyses in confirmatory clinical trials (EMA 2014). The lack of a convenient tool to answer spontaneous questions from different perspectives can hinder an efficient discussion, especially in joint interdisciplinary study teams. With the new application, an easily executed but powerful tool is provided to fill this gap.

Altered pharmacokinetics of combined oral contraceptives in obesity - multistudy assessment

OBJECTIVE

The objective was to evaluate the pharmacokinetics (PKs) of levonorgestrel (LNG)-containing combined oral contraceptives (COCs) in obese women.

STUDY DESIGN

We pooled and reanalyzed data from 89 women with different body mass index (BMI) categories from four clinical studies. The LNG and ethinyl estradiol (EE) PKs were analyzed utilizing a zero-order absorption (K0), two-compartment PK model to evaluate key PK parameters in relation to a range of weights, BMI and body surface area (BSA).

RESULTS

Increasing of body habitus metrics is correlated with decreasing Cmax (p<.0001) and AUCτ (p<.05) for both LNG and EE, but no correlation was found for Cmin (p≥.17). Increasing weight and BMI were associated with a modest increase (p≤.056) of clearance (CL) and appreciable increases of central volume (V1, p<.05), distribution clearance (CLd, p≤.001) and peripheral volume (V2, p<.0001) for LNG. For EE, increases in CL (p≤.009) were found with greater weight, BMI and BSA. Values of V1, CLd and V2 also increased (p<.0001) in obese subjects. The half-life and steady-state volume were greater among obese women (p<.0001) for both LNG and EE. LNG and EE PK parameters correlated well (p≤.006 for all), indicating that individual subject physiology affected both drugs similarly.

CONCLUSIONS

The primary effects of obesity on LNG and EE were a modest increase in CL and a marked increase in distribution parameters. We observed no obesity-related differences in trough LNG and EE concentrations.

IMPLICATIONS

This population PK analysis demonstrated reduced systemic exposure to LNG/EE oral contraceptives in obese subjects (Cmax and AUCτ); these particular differences are unlikely to lower contraceptive effectiveness among obese women who are correctly using LNG-containing contraceptives.

FDA Public Meeting Report on "Drug Interactions With Hormonal Contraceptives: Public Health and Drug Development Implications"

Potential drug interactions with hormonal contraceptives are an important public health concern. A public meeting on "Drug Interactions With Hormonal Contraceptives: Public Health and Drug Development Implication" was hosted by the United States Food and Drug Administration (FDA). The meeting endeavored to provide an opportunity for the FDA to seek input from experts on the public health concerns associated with the use of hormonal contraceptives and interacting drugs that might affect efficacy and safety, including pharmacokinetic/pharmacodynamic considerations, in the design of drug interaction studies of hormonal contraceptives for drug development and approaches to translating the results of drug interaction information into informative labeling and communication. The input received could be used to refine FDA's thinking on hormonal contraceptives drug interaction study design and interpretation and labeling communication of drug interaction risk. This meeting benefited from strong and diverse participation from the Center for Drug Evaluation and Research at the FDA, Centers for Disease Control and Prevention, National Institutes of Health, Swedish Medical Products Agency, pharmaceutical industry, and representatives of academia. This report provides a summary of the key discussion based on the presentations and panel discussion.

Contraceptive Care of Obese Women

Importance

In the United States, 27% of reproductive-aged women are overweight, and 35% are obese. Until recently, contraceptive research excluded women greater than 130% of their ideal body weight. Gaps in data limit evidence-based decision making for effective contraceptive counseling and management in this rapidly growing population.

Objectives

The aims of this summary are to review the benefits, adverse effects, and risk factors associated with contraceptive methods in obese women, with special attention to effectiveness, and provide contraceptive management and counseling recommendations for best clinical practice.

Evidence Acquisition

We performed a thorough search of PubMed for current literature, including original research articles, review articles, and guidelines on contraceptive counseling and management in obese women in the United States. We reviewed the body of evidence with special attention to studies published since recent Cochrane and systematic reviews on this topic.

Conclusions

Contraceptive use is safer than pregnancy, especially for obese women who have increased pregnancy risks. Baseline health is compromised by obesity, but contraceptive risks remain low. Long-acting, reversible contraceptive methods offer superior effectiveness, minimal risk, and numerous noncontraceptive benefits across body mass index groups. No substantial evidence supports ineffectiveness of any method in obese women except oral emergency contraception and the patch. Pharmacokinetic changes of obesity associated with other oral methods do not seem to result in clinically significant declines in effectiveness. Future contraceptive efficacy studies should include obese women to better discuss their contraceptive needs.

Relevance

This review is beneficial for all providers caring for reproductive-aged women wanting to avoid unintended pregnancy.

Are hormonal contraceptives less effective in overweight and obese women?

Loss of efficacy of hormonal contraceptives is of particular concern for women who are overweight or obese. Only recently have clinical trials started to include overweight and obese women in their study populations, limiting the data available on which to make the best prescribing decisions for hormonal contraceptives for these patients. Other methods, such as the copper or levonorgestrel-containing intrauterine device, the etonogestrel implant, and depot medroxyprogesterone acetate, are preferred over combined oral contraceptives, the transdermal patch, and the vaginal ring.

Obesity and gynaecological and obstetric conditions: umbrella review of the literature

Objective To study the strength and validity of associations between adiposity and risk of any type of obstetric or gynaecological conditions.Design An umbrella review of meta-analyses.Data sources PubMed, Cochrane database of systematic reviews, manual screening of references for systematic reviews or meta-analyses of observational and interventional studies evaluating the association between adiposity and risk of any obstetrical or gynaecological outcome.Main outcomes Meta-analyses of cohort studies on associations between indices of adiposity and obstetric and gynaecological outcomes.Data synthesis Evidence from observational studies was graded into strong, highly suggestive, suggestive, or weak based on the significance of the random effects summary estimate and the largest study in the included meta-analysis, the number of cases, heterogeneity between studies, 95% prediction intervals, small study effects, excess significance bias, and sensitivity analysis with credibility ceilings. Interventional meta-analyses were assessed separately.Results 156 meta-analyses of observational studies were included, investigating associations between adiposity and risk of 84 obstetric or gynaecological outcomes. Of the 144 meta-analyses that included cohort studies, only 11 (8%) had strong evidence for eight outcomes: adiposity was associated with a higher risk of endometrial cancer, ovarian cancer, antenatal depression, total and emergency caesarean section, pre-eclampsia, fetal macrosomia, and low Apgar score. The summary effect estimates ranged from 1.21 (95% confidence interval 1.13 to 1.29) for an association between a 0.1 unit increase in waist to hip ratio and risk endometrial cancer up to 4.14 (3.61 to 4.75) for risk of pre-eclampsia for BMI >35 compared with <25. Only three out of these eight outcomes were also assessed in meta-analyses of trials evaluating weight loss interventions. These interventions significantly reduced the risk of caesarean section and pre-eclampsia, whereas there was no evidence of association with fetal macrosomia.Conclusions Although the associations between adiposity and obstetric and gynaecological outcomes have been extensively studied, only a minority were considered strong and without hints of bias.

Safety of hormonal contraception for obese women

INTRODUCTION

Obese women have special safety requirements for contraceptive choice, but the evidence supporting such decision is dispersed and sometimes conflicting. Despite being effective, well tolerated and safe for most women, hormonal contraceptives are underused by obese women due to fear of contraceptive failure, weight gain and venous thrombosis. Areas covered: We performed a comprehensive literature search to identify studies about hormonal contraception in overweight and obese women, including safety concerns. We considered the safety of hormonal contraceptives for otherwise healthy obese women and for those with comorbidities such as hypertension, diabetes, vascular disease, or a history of deep venous thrombosis. Expert opinion: Over time there is no convincing evidence that obesity increases the risk of contraceptive failure. Hormonal contraceptive users may have a modest weight gain that is comparable to that of non-users. Current evidence supports the safe use of combined hormonal contraceptives by obese women after detailed clinical screening to exclude comorbidities that may contraindicate the use of estrogens. Progestin-only methods are generally safe, and long-acting reversible contraceptives hold the best combination of efficacy, safety and convenience for this group, although individualization is advisable.

Healthcare Provider Attitudes Regarding Contraception for Women with Obesity

BACKGROUND

Whether providers who regularly provide family planning services consider contraceptive methods as unsafe for women with obesity is unknown.

METHODS

We analyzed questionnaire responses received from December 2009 to March 2010 from 635 office-based physicians and 1323 Title X clinic providers delivering family planning services, who were randomly sampled (response rate 65%) before the release of national evidence-based contraception guidelines. We examined provider and clinical setting characteristics and clinic patient demographics for association with provider misconceptions about safety of combined oral contraceptives (COCs), depot medroxyprogesterone acetate (DMPA), or intrauterine devices (IUDs) for women with obesity. If providers considered methods as unsafe or do not know, we categorized those responses as misconceptions. We used multivariable logistic regression to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs).

RESULTS

A substantial proportion of respondents had misconceptions about the safety of COCs (31%), DMPA (24%), copper (Cu) (18%), and levonorgestrel (LNG)-IUDs (16%) for women with obesity. Provider type was associated with increased odds of misconceptions for all four methods compared with office-based obstetrician/gynecologists. Not having the method available onsite was associated with safety misconceptions of DMPA (aOR 1.90, 95% CI 1.07-3.36), Cu-IUD (aOR 4.19, 95% CI 1.51-11.61), and LNG-IUD (aOR 5.25, 95% CI 1.67-16.49).

CONCLUSION

While the majority of providers considered all four contraceptive methods safe for women with obesity, substantial proportions had misconceptions about safety of COCs, DMPA, and IUDs. Provider education, particularly among certain specialties, is needed to increase knowledge regarding moderate and highly effective contraceptive methods among this patient population.

Safety and effectiveness data for emergency contraceptive pills among women with obesity: a systematic review

OBJECTIVE

This study aims to determine whether emergency contraceptive pills (ECPs) are less safe and effective for women with obesity compared with those without obesity.

STUDY DESIGN

We searched PubMed for articles through November 2015 regarding the safety and effectiveness of ECPs [ulipristal acetate (UPA), levonorgestrel (LNG) and combined estrogen and progestin] among obese users. We assessed study quality using the United States Preventive Services Task Force evidence grading system.

RESULTS

We identified four pooled secondary analyses (quality: poor to fair), two of which examined UPA and three examined LNG formulations. Three analyses pooled overlapping data from a total of three primary studies and demonstrated significant associations between obesity and risk of pregnancy after ECP use. One analysis reported a 4-fold increased risk of pregnancy among women with obesity (BMI≥30kg/m2) compared with women within normal/underweight categories (BMI<25kg/m2) after use of LNG ECPs [odds ratio (OR) 4.4; 95% confidence interval (CI) 2.0-9.4]. Further analysis of the same LNG data found that, at an approximate weight of 80 kg, the rate of pregnancy rose above 6%, which is the estimated pregnancy probability without contraception; at weights less than 75 kg, the rate of pregnancy was less than 2%. Two analyses examining UPA suggested an approximate 2-fold increased risk of pregnancy among women with obesity compared with either normal/underweight women or nonobese (BMI<30kg/m2) women (OR 2.6; 95% CI 0.9-7.0 and OR 2.1; 95% CI 1.0-4.3, respectively), but CIs were wide. Finally, the fourth secondary analysis pooled data from three separate randomized controlled trials on LNG ECPs and found no increase in pregnancy risk with increasing weight or BMI and found no consistent association between pregnancy and both factors when adjusted for other covariates.

CONCLUSION

While data are limited and poor to fair quality, findings suggest that women with obesity experience an increased risk of pregnancy after use of LNG ECP compared with those normal/underweight. Women with obesity may also experience an increased risk of pregnancy compared with women without obesity after use of UPA ECP, though differences did not reach statistical significance. Providers should counsel all women at risk for unintended pregnancy, including those with obesity, about the effectiveness of the full range of emergency contraception options in order for them to understand their options, to receive advanced supplies of emergency contraception as needed and to understand how to access an emergency copper intrauterine device if desired.

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.

Clarification of contraceptive drug pharmacokinetics in obesity

Related to concerns about the role of obesity in the efficacy of contraceptive drugs, a review of the literature was carried out in regard to the pharmacokinetics of ethinyl estradiol and various progestins given by various routes of administration. Most studies show that obese women exhibit modestly lower plasma concentrations of these drugs (circa 30%) when given the same doses as normal-weight women. While the mechanism is uncertain, precedence in the literature suggests that this is due to body weight-related differences in metabolism rates. Confusing in some of the literature is that a few studies have reported erroneously calculated pharmacokinetic parameters after multiple dosing of oral contraceptives. A demonstration of appropriate pharmacokinetic methodology is provided.

Do women aged over 40 need different counseling on combined hormonal contraception?

There is still a risk of pregnancy during the menopause transition, for most women after the age of 40, as occasional, spontaneous ovulation can occur. Women in this age group may therefore consider using contraception and want appropriate counseling. Aging is accompanied by changes that can increase the risks associated with the use of combined hormonal contraceptives (CHCs), but we do not have sufficient evidence to determine whether age alone increases the risks of using CHCs or whether there are additional risks if CHC use begins at an earlier age. Another issue is whether we can differentiate between initiator versus continuation influences on risk. The objective of this article is to review the risks associated with CHC to determine whether there is a need for more appropriate contraceptive counseling for women aged over 40.