Impact of bodyweight/body mass index on the effectiveness of emergency contraception with levonorgestrel: a pooled-analysis of three randomized controlled trials

Emergency contraception - A review

Emergency contraception (EC), or postcoital contraception, is a therapy aimed at preventing unintended pregnancy after an act of unprotected or under-protected sexual intercourse. Options include both emergency contraceptive pills (most commonly containing levonorgestrel or ulipristal acetate) and insertion of an intrauterine device. The aim of this paper is to summarize current evidence surrounding the use of emergency contraceptives and to present an evidence-based approach to EC provision. Emergency contraception is a safe and effective option in preventing unwanted pregnancy, irrespective of age, weight, or breastfeeding status. Efforts should be made to increase their availability, as well as knowledge of these methods, both among patients and healthcare providers.

Model-Informed Approaches to Support Drug Development for Patients With Obesity: A Regulatory Perspective

Obesity, which is defined as having a body mass index of 30 kg/m2 or greater, has been recognized as a serious health problem that increases the risk of many comorbidities (eg, heart disease, stroke, and diabetes) and mortality. The high prevalence of individuals who are classified as obese calls for additional considerations in clinical trial design. Nevertheless, gaining a comprehensive understanding of how obesity affects the pharmacokinetics (PK), pharmacodynamics (PD), and efficacy of drugs proves challenging, primarily as obese patients are seldom selected for enrollment at the early stages of drug development. Over the past decade, model-informed drug development (MIDD) approaches have been increasingly used in drug development programs for obesity and its related diseases as they use and integrate all available sources and knowledge to inform and facilitate clinical drug development. This review summarizes the impact of obesity on PK, PD, and the efficacy of drugs and, more importantly, provides an overview of the use of MIDD approaches in drug development and regulatory decision making for patients with obesity: estimating PK, PD, and efficacy in specific dosing scenarios, optimizing dose regimen, and providing evidence for seeking new indication(s). Recent review cases using MIDD approaches to support dose selection and provide confirmatory evidence for effectiveness for patients with obesity, including pediatric patients, are discussed. These examples demonstrate the promise of MIDD as a valuable tool in supporting clinical trial design during drug development and facilitating regulatory decision-making processes for the benefit of patients with obesity.

Levonorgestrel emergency contraception and bodyweight: are current recommendations consistent with historic data?

Objective

To assess the consistency between current recommendations that women of body weight (BW) or body mass index (BMI) above a defined threshold should use a double dose of levonorgestrel (LNG) for emergency contraception (EC) and observed frequency of pregnancy in historic studies of single-dose LNG for EC.

Methods

We applied double dose recommendation criteria to individual participant level data from three historic studies of the WHO’s Human Reproductive Program to categorize subjects into single dose-recommended (SDR) and double dose-recommended (DDR) groups and compared the latter to the former using pregnancy risk ratios (RR).

Results

A total of 5859 subjects with 59 pregnancies made up the full dataset. Depending on the recommendation source (USA or UK) and inclusion or exclusion of heavy outlier data, DDR criteria were satisfied by 3.7% to 18.9% of subjects. Pregnancy proportions were mostly lower in DDR than in SDR subjects, with risk ratio estimates ranging from zero to 1.17, exceeding unity only when the USA criterion was used with outliers included. DDR subjects had a significantly lower relative frequency of pregnancy than SDR subjects when the UK criteria were used and outliers excluded (RR = 0.17 [95% CI: 0.04; 0.70], p = .0024).

Conclusions

Our findings are consistent with the notion that there is no real loss of pregnancy control with single-dose LNG-EC in high-BMI and/or high-BW users, and today’s double dose recommendations were prematurely issued and remain questionable.

Levonorgestrel emergency contraception and bodyweight

Objectives: Emergency contraception (EC) provides an opportunity to avoid an unwanted pregnancy following unprotected sexual intercourse (UPSI), failure of a regular contraceptive method, or after sexual assault. Two main methods are currently available: oral pills or the copper-T intrauterine device. In recent years there has been some debate regarding the efficacy of oral therapy in obese women. In this brief commentary we review new evidence, published after the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) referral of 2014, relating to the effect of obesity on the pharmacokinetics and clinical efficacy of levonorgestrel EC in light of some of the concerns that have been raised. Methods: A PubMed literature search ("levonorgestrel" and "emergency contraception") was conducted between 1 January 2005 to 31 March 2018; results from the main clinical trials are discussed. Additional literature known to the authors and identified from the reference lists of cited publications was included. Results: Overall, it should be noted that, in studies which determined pregnancy rates across different weight or BMI categories, the overall pregnancy rate was low (1-2%) and there was no direct evidence that lower levonorgestrel plasma levels contributed to an increased pregnancy rate in obese women. This conclusion was reached by the EMA referral in 2014 and they concluded that emergency contraceptive pills (ECPs) could be taken regardless of body weight or BMI, as soon as possible after UPSI. Since the EMA review, additional evidence has been published regarding this topic. This includes PK data (which can neither support, nor deny the previously submitted meta-analyses during the Article 31 Referral procedure), or re-analyses of the previously submitted data. Conclusions: Evidence published since the EMA referral in 2014 does not change the original conclusions of the agency, which recommended that ECPs could be taken regardless of body weight or BMI, as soon as possible after UPSI.

Pharmacokinetics of the 1.5 mg levonorgestrel emergency contraceptive in women with normal, obese and extremely obese body mass index

OBJECTIVE

To assess the pharmacokinetics (PK) of levonorgestrel after 1.5 mg oral doses (LNG-EC) in women with normal, obese and extremely obese body mass index (BMI).

STUDY DESIGN

The 1.5 mg LNG dose was given to healthy, reproductive-age, ovulatory women with normal BMI (mean 22.0), obese (mean 34.4), and extremely obese (mean 46.6 kg/m2) BMI. Total serum LNG was measured over 0 to 96 h by radioimmunoassay while free and bioavailable LNG were calculated. The maximum concentration (Cmax), time to maximum concentration (Tmax), and area under the curve (AUC) of LNG were assessed. Pharmacokinetic parameters calculated included half-life (t1/2), clearance (CL) and volume of distribution (Vss).

RESULTS

Ten normal-BMI, 11 obese-BMI, 5 extremely obese-BMI women were studied. After LNG-EC, mean total LNG metrics were lower in the obese and extremely obese groups compared to normal (Cmax 10.5 and 10.5 versus 16.2 ng/mL, both p<.01; AUC 208 and 197 versus 360 h × ng/mL, both p<.05). Mean bioavailable LNG Cmax was lower in obese (7.03 ng/mL, p<.05) and extremely obese (7.53 ng/ml, p=.198) compared to normal BMI (9.39 ng/mL). Mean bioavailable LNG AUC values were lower in obese and extremely obese compared to normal (131.6 and 127.5 vs 185.0 h × ng/mL, p<.05 for both).

CONCLUSIONS

Obese and extremely obese women were exposed to lower total and bioavailable LNG than normal BMI women.

IMPLICATIONS

Lower 'bioavailable' (free plus albumin bound) LNG AUC in obese women may play a role in the purported reduced efficacy of LNG-EC in obese users.

Use of levonorgestrel as emergency contraception in overweight women

OBJECTIVE

Levonorgestrel (LNG) emergency contraception (EC) may have decreased efficacy for women with body mass indices (BMI)≥26kg/m². This study aims to evaluate the prevalence of LNG EC use and EC counseling among overweight women.

METHODS

The 2013-2015 dataset from the National Survey of Family Growth was analyzed to determine the proportion of women with BMI≥26kg/m² who report recent use of LNG EC and EC counseling.

RESULTS

Overall, 2.4% of respondents reported recent use of LNG EC. Among women using oral LNG for EC, 29.8% of survey participants reported BMI≥26kg/m². Additionally, 40.2% of women with BMI≥26kg/m² using oral LNG EC reported having a doctor or medical provider talk to them about emergency contraception within the last 12 months, compared to 18.3% of LNG EC users with BMI<26kg/m² (p<0.001).

CONCLUSIONS

Despite recent counseling from clinicians and concerns for decreased efficacy, a significant number of overweight women continue to use LNG for EC. Clinicians should counsel women with BMI≥26kg/m² on the potential limitations of oral LNG for EC and offer more effective EC methods, including the copper intrauterine device and oral ulipristal acetate.

Interventions for emergency contraception

BACKGROUND

Emergency contraception (EC) is using a drug or copper intrauterine device (Cu-IUD) to prevent pregnancy shortly after unprotected intercourse. Several interventions are available for EC. Information on the comparative effectiveness, safety and convenience of these methods is crucial for reproductive healthcare providers and the women they serve. This is an update of a review previously published in 2009 and 2012.

OBJECTIVES

To determine which EC method following unprotected intercourse is the most effective, safe and convenient to prevent pregnancy.

SEARCH METHODS

In February 2017 we searched CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, Popline and PubMed, The Chinese biomedical databases and UNDP/UNFPA/WHO/World Bank Special Programme on Human Reproduction (HRP) emergency contraception database. We also searched ICTRP and ClinicalTrials.gov as well as contacting content experts and pharmaceutical companies, and searching reference lists of appropriate papers.

SELECTION CRITERIA

Randomised controlled trials including women attending services for EC following a single act of unprotected intercourse were eligible.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. The primary review outcome was observed number of pregnancies. Side effects and changes of menses were secondary outcomes.

MAIN RESULTS

We included 115 trials with 60,479 women in this review. The quality of the evidence for the primary outcome ranged from moderate to high, and for other outcomes ranged from very low to high. The main limitations were risk of bias (associated with poor reporting of methods), imprecision and inconsistency.Comparative effectiveness of different emergency contraceptive pills (ECP)Levonorgestrel was associated with fewer pregnancies than Yuzpe (estradiol-levonorgestrel combination) (RR 0.57, 95% CI 0.39 to 0.84, 6 RCTs, n = 4750, I2 = 23%, high-quality evidence). This suggests that if the chance of pregnancy using Yuzpe is assumed to be 29 women per 1000, the chance of pregnancy using levonorgestrel would be between 11 and 24 women per 1000.Mifepristone (all doses) was associated with fewer pregnancies than Yuzpe (RR 0.14, 95% CI 0.05 to 0.41, 3 RCTs, n = 2144, I2 = 0%, high-quality evidence). This suggests that if the chance of pregnancy following Yuzpe is assumed to be 25 women per 1000 women, the chance following mifepristone would be between 1 and 10 women per 1000.Both low-dose mifepristone (less than 25 mg) and mid-dose mifepristone (25 mg to 50 mg) were probably associated with fewer pregnancies than levonorgestrel (RR 0.72, 95% CI 0.52 to 0.99, 14 RCTs, n = 8752, I2 = 0%, high-quality evidence; RR 0.61, 95% CI 0.45 to 0.83, 27 RCTs, n = 6052, I2 = 0%, moderate-quality evidence; respectively). This suggests that if the chance of pregnancy following levonorgestrel is assumed to be 20 women per 1000, the chance of pregnancy following low-dose mifepristone would be between 10 and 20 women per 1000; and that if the chance of pregnancy following levonorgestrel is assumed to be 35 women per 1000, the chance of pregnancy following mid-dose mifepristone would be between 16 and 29 women per 1000.Ulipristal acetate (UPA) was associated with fewer pregnancies than levonorgestrel (RR 0.59; 95% CI 0.35 to 0.99, 2 RCTs, n = 3448, I2 = 0%, high-quality evidence).Comparative effectiveness of different ECP dosesIt was unclear whether there was any difference in pregnancy rate between single-dose levonorgestrel (1.5 mg) and the standard two-dose regimen (0.75 mg 12 hours apart) (RR 0.84, 95% CI 0.53 to 1.33, 3 RCTs, n = 6653, I2 = 0%, moderate-quality evidence).Mid-dose mifepristone was associated with fewer pregnancies than low-dose mifepristone (RR 0.73; 95% CI 0.55 to 0.97, 25 RCTs, n = 11,914, I2 = 0%, high-quality evidence).Comparative effectiveness of Cu-IUD versus mifepristoneThere was no conclusive evidence of a difference in the risk of pregnancy between the Cu-IUD and mifepristone (RR 0.33, 95% CI 0.04 to 2.74, 2 RCTs, n = 395, low-quality evidence).Adverse effectsNausea and vomiting were the main adverse effects associated with emergency contraception. There is probably a lower risk of nausea (RR 0.63, 95% CI 0.53 to 0.76, 3 RCTs, n = 2186 , I2 = 59%, moderate-quality evidence) or vomiting (RR 0.12, 95% CI 0.07 to 0.20, 3 RCTs, n = 2186, I2 = 0%, high-quality evidence) associated with mifepristone than with Yuzpe. levonorgestrel is probably associated with a lower risk of nausea (RR 0.40, 95% CI 0.36 to 0.44, 6 RCTs, n = 4750, I2 = 82%, moderate-quality evidence), or vomiting (RR 0.29, 95% CI 0.24 to 0.35, 5 RCTs, n = 3640, I2 = 78%, moderate-quality evidence) than Yuzpe. Levonorgestrel users were less likely to have any side effects than Yuzpe users (RR 0.80, 95% CI 0.75 to 0.86; 1 RCT, n = 1955, high-quality evidence). UPA users were more likely than levonorgestrel users to have resumption of menstruation after the expected date (RR 1.65, 95% CI 1.42 to 1.92, 2 RCTs, n = 3593, I2 = 0%, high-quality evidence). Menstrual delay was more common with mifepristone than with any other intervention and appeared to be dose-related. Cu-IUD may be associated with higher risks of abdominal pain than mifepristone (18 events in 95 women using Cu-IUD versus no events in 190 women using mifepristone, low-quality evidence).

AUTHORS' CONCLUSIONS

Levonorgestrel and mid-dose mifepristone (25 mg to 50 mg) were more effective than Yuzpe regimen. Both mid-dose (25 mg to 50 mg) and low-dose mifepristone(less than 25 mg) were probably more effective than levonorgestrel (1.5 mg). Mifepristone low dose (less than 25 mg) was less effective than mid-dose mifepristone. UPA may be more effective than levonorgestrel.Levonorgestrel users had fewer side effects than Yuzpe users, and appeared to be more likely to have a menstrual return before the expected date. UPA users were probably more likely to have a menstrual return after the expected date. Menstrual delay was probably the main adverse effect of mifepristone and seemed to be dose-related. Cu-IUD may be associated with higher risks of abdominal pain than ECPs.

Interventions for emergency contraception

BACKGROUND

Emergency contraception (EC) is using a drug or copper intrauterine device (Cu-IUD) to prevent pregnancy shortly after unprotected intercourse. Several interventions are available for EC. Information on the comparative effectiveness, safety and convenience of these methods is crucial for reproductive healthcare providers and the women they serve. This is an update of a review previously published in 2009 and 2012.

OBJECTIVES

To determine which EC method following unprotected intercourse is the most effective, safe and convenient to prevent pregnancy.

SEARCH METHODS

In February 2017 we searched CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, Popline and PubMed, The Chinese biomedical databases and UNDP/UNFPA/WHO/World Bank Special Programme on Human Reproduction (HRP) emergency contraception database. We also searched ICTRP and ClinicalTrials.gov as well as contacting content experts and pharmaceutical companies, and searching reference lists of appropriate papers.

SELECTION CRITERIA

Randomised controlled trials including women attending services for EC following a single act of unprotected intercourse were eligible.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures recommended by Cochrane. The primary review outcome was observed number of pregnancies. Side effects and changes of menses were secondary outcomes.

MAIN RESULTS

We included 115 trials with 60,479 women in this review. The quality of the evidence for the primary outcome ranged from moderate to high, and for other outcomes ranged from very low to high. The main limitations were risk of bias (associated with poor reporting of methods), imprecision and inconsistency. Comparative effectiveness of different emergency contraceptive pills (ECP)Levonorgestrel was associated with fewer pregnancies than Yuzpe (estradiol-levonorgestrel combination) (RR 0.57, 95% CI 0.39 to 0.84, 6 RCTs, n = 4750, I2 = 23%, high-quality evidence). This suggests that if the chance of pregnancy using Yuzpe is assumed to be 29 women per 1000, the chance of pregnancy using levonorgestrel would be between 11 and 24 women per 1000.Mifepristone (all doses) was associated with fewer pregnancies than Yuzpe (RR 0.14, 95% CI 0.05 to 0.41, 3 RCTs, n = 2144, I2 = 0%, high-quality evidence). This suggests that if the chance of pregnancy following Yuzpe is assumed to be 25 women per 1000 women, the chance following mifepristone would be between 1 and 10 women per 1000.Both low-dose mifepristone (less than 25 mg) and mid-dose mifepristone (25 mg to 50 mg) were probably associated with fewer pregnancies than levonorgestrel (RR 0.72, 95% CI 0.52 to 0.99, 14 RCTs, n = 8752, I2 = 0%, high-quality evidence; RR 0.61, 95% CI 0.45 to 0.83, 27 RCTs, n = 6052, I2 = 0%, moderate-quality evidence; respectively). This suggests that if the chance of pregnancy following levonorgestrel is assumed to be 20 women per 1000, the chance of pregnancy following low-dose mifepristone would be between 10 and 20 women per 1000; and that if the chance of pregnancy following levonorgestrel is assumed to be 35 women per 1000, the chance of pregnancy following mid-dose mifepristone would be between 16 and 29 women per 1000.Ulipristal acetate (UPA) was associated with fewer pregnancies than levonorgestrel (RR 0.59; 95% CI 0.35 to 0.99, 2 RCTs, n = 3448, I2 = 0%, high-quality evidence). Comparative effectiveness of different ECP dosesIt was unclear whether there was any difference in pregnancy rate between single-dose levonorgestrel (1.5 mg) and the standard two-dose regimen (0.75 mg 12 hours apart) (RR 0.84, 95% CI 0.53 to 1.33, 3 RCTs, n = 6653, I2 = 0%, moderate-quality evidence).Mid-dose mifepristone was associated with fewer pregnancies than low-dose mifepristone (RR 0.73; 95% CI 0.55 to 0.97, 25 RCTs, n = 11,914, I2 = 0%, high-quality evidence). Comparative effectiveness of Cu-IUD versus mifepristoneThere was no conclusive evidence of a difference in the risk of pregnancy between the Cu-IUD and mifepristone (RR 0.33, 95% CI 0.04 to 2.74, 2 RCTs, n = 395, low-quality evidence). Adverse effectsNausea and vomiting were the main adverse effects associated with emergency contraception. There is probably a lower risk of nausea (RR 0.63, 95% CI 0.53 to 0.76, 3 RCTs, n = 2186 , I2 = 59%, moderate-quality evidence) or vomiting (RR 0.12, 95% CI 0.07 to 0.20, 3 RCTs, n = 2186, I2 = 0%, high-quality evidence) associated with mifepristone than with Yuzpe. levonorgestrel is probably associated with a lower risk of nausea (RR 0.40, 95% CI 0.36 to 0.44, 6 RCTs, n = 4750, I2 = 82%, moderate-quality evidence), or vomiting (RR 0.29, 95% CI 0.24 to 0.35, 5 RCTs, n = 3640, I2 = 78%, moderate-quality evidence) than Yuzpe. Levonorgestrel users were less likely to have any side effects than Yuzpe users (RR 0.80, 95% CI 0.75 to 0.86; 1 RCT, n = 1955, high-quality evidence). UPA users were more likely than levonorgestrel users to have resumption of menstruation after the expected date (RR 1.65, 95% CI 1.42 to 1.92, 2 RCTs, n = 3593, I2 = 0%, high-quality evidence). Menstrual delay was more common with mifepristone than with any other intervention and appeared to be dose-related. Cu-IUD may be associated with higher risks of abdominal pain than mifepristone (18 events in 95 women using Cu-IUD versus no events in 190 women using mifepristone, low-quality evidence).

AUTHORS' CONCLUSIONS

Levonorgestrel and mid-dose mifepristone (25 mg to 50 mg) were more effective than Yuzpe regimen. Both mid-dose (25 mg to 50 mg) and low-dose mifepristone(less than 25 mg) were probably more effective than levonorgestrel (1.5 mg). Mifepristone low dose (less than 25 mg) was less effective than mid-dose mifepristone. UPA was more effective than levonorgestrel.Levonorgestrel users had fewer side effects than Yuzpe users, and appeared to be more likely to have a menstrual return before the expected date. UPA users were probably more likely to have a menstrual return after the expected date. Menstrual delay was probably the main adverse effect of mifepristone and seemed to be dose-related. Cu-IUD may be associated with higher risks of abdominal pain than ECPs.

The not so over-the-counter status of emergency contraception in Ontario: A mixed methods study with pharmacists

Introduction: In Canada, the progestin-only dedicated pill is the most widely used method of emergency contraception (EC). This method gained over-the-counter status in Ontario in 2008. Our mixed methods study explored the progestin-only EC knowledge, attitudes, and provision practices of Ontario pharmacists.

Methods: From June 2015 to October 2015, we collected 198 mailed surveys from Ontarian pharmacy representatives and conducted 17 in-depth interviews with a subset of respondents. We analyzed these data using descriptive statistics and for content and themes.

Results: Results from our English/French bilingual survey indicate that respondents’ knowledge is generally accurate, but confusion persists about the mechanism of action and the number of times the drug can be used in one menstrual cycle. Nearly half (49%) of our survey respondents indicated that progestin-only EC pills are only available behind the counter. Interviewees strongly supported the introduction and promotion of more effective methods of EC in Ontario.

Conclusion: Continuing education focusing on both the regulatory status of progestin-only EC and information about the medication appears warranted. Health Canada’s recent approval of ulipristal acetate for use as a post-coital contraceptive may provide a window of opportunity for engaging with health service providers, including pharmacists, about all available modalities of EC in Canada.

Pharmacokinetics of levonorgestrel and ulipristal acetate emergency contraception in women with normal and obese body mass index

OBJECTIVE

This study compares the pharmacokinetics (PK) of levonorgestrel (LNG) emergency contraceptive (EC) and ulipristal acetate (UPA)-EC between normal-body mass index (BMI) and obese-BMI women.

STUDY DESIGN

This prospective, randomized crossover study evaluates the PK of women after single doses of LNG-EC (1.5mg) and UPA-EC (30mg). Study procedures took place during clinical research unit admissions, where participants received a standardized meal and each study drug, in random order, during two separate 24-h admissions. Study staff collected 14 blood specimens (0, 0.5, 1.0, 1.5, 2, 3, 4, 6, 8, 10, 12, 16, 24 and 48h). We evaluated serum concentrations of LNG and UPA using liquid chromatography-tandem mass spectroscopy and estimated the PK parameters of both drugs using noncompartmental analysis. The main outcome of this study was a comparison of between-group differences in AUC_0-24.

RESULTS

Thirty-two women completed the study (16 in each group). Among normal-BMI and obese-BMI participants, the mean BMIs were 22.0 (range 18.8-24.6) and 34.3 (range 30.6-39.9), respectively. After LNG-EC, mean AUC_0-24 and maximum concentration (C_max) were 50% lower among obese-BMI women than among normal-BMI women (AUC_0-24 100.8 vs. 208.5ng*h/mL, IQR_obese-BMI 35.8, IQR_normal-BMI 74.2, p≤.01; C_max 10.8 vs. 18.2ng/mL, p=.01). After UPA-EC, AUC_0-24 and C_max were similar between obese-BMI and normal-BMI women (AUC_0-24 362.5 vs. 293.5ng*h/mL, IQR_obese-BMI 263.2, IQR_normal-BMI 112.5, p=.15; C_max 95.6 vs. 89.3ng/mL, p=.70).

CONCLUSION

After a single dose of EC, obese-BMI women are exposed to lower concentrations of LNG and similar concentrations of UPA, when compared to normal-BMI women.

IMPLICATIONS

Differences in LNG-EC PK by BMI group may underlie and account for the lower LNG-EC efficacy reported among obese-BMI women, but modest differences in UPA-EC PK by BMI group provide less support for variable efficacy. A pharmacodynamic study may be able to clarify whether these PK differences account for observed differences in LNG-EC and UPA-EC efficacy.

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 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.

Effect of BMI and body weight on pregnancy rates with LNG as emergency contraception: analysis of four WHO HRP studies

Objective

To estimate the effect of increased body weight and body mass index (BMI) on pregnancy rates with levonorgestrel (LNG) 1.5 mg used as emergency contraception (EC).

Methods

The study reviewed data from 6873 women in four WHO-HRP randomized trials on EC conducted between 1993 and 2010. Participants took either 1.5 mg of LNG as a single dose or in two doses 12 h apart, up to 120 h of unprotected intercourse. Contraceptive efficacy (pregnancy rates) at different weight and BMI categories was evaluated.

Results

Overall pregnancy rate was low at 1.2%. Pregnancy rates were also low in women weighing over 80 kg (0.7%) and who were obese (BMI over 30 kg/m²) (2.0%). The pooled analyses for pregnancy demonstrated that BMI over 30 kg/m² decreased efficacy significantly (odds ratio 8.27, 95% confidence interval = 2.70–25.37) when compared to women in lower BMI categories, mainly influenced by pregnancies in obese women from one study site. Sensitivity analyses excluding that site showed that obesity was no longer a risk factor; however, the other studies included too few obese women in the sample to exclude a substantial decrease in efficacy.

Conclusions

Pregnancy rates with use of LNG 1.5 mg for EC were low at less than 3% across different weight and BMI categories. Pooled analyses showed an increase in pregnancy rates among obese women (BMI more than 30 kg/m²) compared to women with normal BMI levels, influenced by pregnancies all coming from one study site.

Implications

Access to LNG as EC should still be promoted to women who need them, and not be restricted in any weight or BMI category, with additional attention for counselling and advice for obese women.