Microdose intravaginal levonorgestrel contraception: a multicentre clinical trial. III. The relationship between pregnancy rate and body weight. World Health Organization. Task Force on Long-Acting Systemic Agents for Fertility Regulation. Contraceptive efficacy and cycle control with the Ortho Evra/Evra transdermal system: the analysis of pooled data. Contraceptive failure rates of etonogestrel subdermal implants in overweight and obese women. Levonorgestrel concentrations during use of levonorgestrel rod (LNG ROD) implants. Association between efficacy and body weight or body mass index for two low-dose oral contraceptives. Effectiveness of Norplant implants through seven years: a large-scale study in China. Pre-introductory clinical trials of Norplant implants: a comparison of seventeen countries' experience. Contraceptive efficacy and safety of DMPA-SC. Body weight does not impact pregnancy rates during use of a low-dose extended-regimen 91-day oral contraceptive.
This paper investigates the relationship between pregnancy rates and body weight of 1005 women using a vaginal ring releasing 20 micrograms levonorgestrel per 24 hours. While the overall pregnancy rate at one year was 3.7%, it was found that women have an increasing risk of pregnancy with increasing body weight. For example, a woman of 40 kg has an estimated pregnancy rate of 1.7% in contrast to 9.8% for a woman of 80 kg weight. To present efficacy and cycle control data pooled from three pivotal studies of the contraceptive patch (Ortho Evra/Evra).
                Three multicenter, open-label, contraceptive studies that included up to 13 treatment cycles.Setting: 183 centers.
                3,319 women.Intervention(s): Three consecutive 7-day patches (21 days) with 1 patch-free week per cycle.
                Contraceptive efficacy and cycle control.
                Overall and method failure life-table estimates of contraceptive failure through 13 cycles were 0.8% (95% CI, 0.3%-1.3%) and 0.6% (95% CI, 0.2%-0.9%), respectively. Corresponding Pearl indices were 0.88 (95% CI, 0.44-1.33) and 0.7 (95% CI, 0.31-1.10). Contraceptive failure among women with a body weight < 90 kg (<198 lb) was low and uniformly distributed across the weight range. A subgroup of women with body weight > or = 90 kg (> or = 198 lb) may have increased risk of pregnancy. The incidence of breakthrough bleeding was low and decreased over time.
                In contraceptive patch users, the overall annual probability of pregnancy was 0.8% and the method failure probability was 0.6%. The efficacy of the patch was high and similar across age and racial groups. Among women < 90 kg (<198 lb), contraceptive failure was low and uniformly distributed across the range of body weights. In women > or = 90 kg (> or = 198 lb), contraceptive failures may be increased. Efficacy and cycle control have been shown to be comparable to an established oral contraceptive. To estimate the contraceptive failure rates of the etonogestrel subdermal contraceptive implant in overweight and obese women and compare failure rates with women of normal weight and women using intrauterine devices (IUDs).
                The Contraceptive CHOICE Project is a large prospective cohort study designed to promote the use of long-acting reversible contraceptive methods to reduce unintended pregnancies in the St Louis region. Participants are provided reversible contraception of their choice at no cost. We collected baseline height and weight of each participant. During each survey, participants were asked about missed menses and possible pregnancies. Any participant who suspected a pregnancy was asked to come in for urine pregnancy testing. Analysis includes the first 8,445 participants enrolled in CHOICE of which 1,168 chose the implant and 4,200 chose the IUD. Student's t test, χ test, and Kaplan-Meier survival curves were used to perform statistical analyses to estimate failure rates in overweight and obese women using the implant and IUDs.
                Of the women choosing the implant, 28% were overweight and 35% were obese. Of the women who chose an IUD, 27% were overweight and 35% were obese. The 3-year cumulative failure rates for implant and IUD users were less than one per 100 women-years and did not vary by body mass index.
                We found no decrease in the effectiveness of the implant in overweight or obese women. The implant may be offered as a first-line contraceptive method to any woman seeking a reversible and reliable birth control method. In a three-year randomized trial that included 398 women, blood samples were collected for the purpose of assaying levonorgestrel concentrations in women using a new two-rod contraceptive implant system or an earlier implant formulation, Norplant-2 implants. Sample collection was at 1, 3, 6, 9, and 12 months after placement and semiannually thereafter through three years. Resulting assays and analyses showed that levonorgestrel concentrations of each implant formulation decreased significantly with time after placement, with increasing body weight, and with ponderal index. In the third year, several measures indicated that concentrations of the contraceptive drug were higher in women using the LNG ROD implants than in users of the original formulation. No pregnancies occurred among women in either group in the three years. This study provides evidence that the minimum levonorgestrel concentration needed to protect against pregnancy is below 200 pg/ml, and possibly is below 175 pg/ml. This analysis investigated the association of oral contraceptive efficacy with body weight and body mass index (BMI) for hypothesis-generating purposes.
                Data were from a randomized, parallel-group trial of 180/215/250 mcg of norgestimate (NGM)/25 mcg of ethinyl estradiol (EE) (given to 1671 women) and 1 mg of norethindrone acetate (NETA)/20 mcg of EE (given to 1139 women). Pregnancies were evaluated across BMI deciles and by BMI and body weight dichotomies. A Pearl index was calculated for each treatment group. The relative risk (RR) of pregnancy was calculated with a Cox proportional hazards model.
                The Pearl index for women who received NGM/EE was 2.36 [95% confidence interval (CI)=1.33-3.40]; for those who received NETA/EE, the Pearl index was 3.29 (95% CI=1.81-4.77). Consistent, weak positive associations between weight and pregnancy risk were found. Overall, for women with a BMI >or=25 kg/m(2) (compared with women with a BMI <25 kg/m(2)), the RR of pregnancy was 1.84 (95% CI=0.98-3.45); that for women who received NGM/EE was 1.39 (95% CI=0.57-3.40), whereas that for women who received NETA/EE was 2.49 (95% CI=1.01-6.13). For women with a body weight >or=70 kg (compared with women with a body weight <70 kg), the RR was 1.25 (95% CI=0.63-2.46); that for women who received NGM/EE was 1.41 (95% CI=0.56-3.54), whereas that for women who received NETA/EE was 1.12 (95% CI=0.40-3.12).
                Women in the higher body weight or BMI category showed a small increase in the risk of pregnancy with these oral contraceptives, but this increase was not statistically significant overall or for either formulation studied. The effectiveness of Norplant implants over a seven year period of continuous use was studied in a multicenter trial. Pregnancy rates were 0.4 per 100 in both year six and year seven. More than 3,600 women completed 6 years and more than 2,400 women completed 7 years. Pregnancy rates increased with weight (p < .05) and decreased with age, but in years 6 and 7 combined, the pregnancy rate neither reached nor exceeded 1 per 100 woman years in any 5 year age group or in any 10 kg weight group. This report summarizes the data collected in pre-introductory Norplant implants clinical trials in 17 countries in Latin America, Asia and Africa that were coordinated by either the Population Council or Family Health International (FHI) between 1984 and 1991. A total of 16,282 women between the ages of 18 and 40 years participated in the studies with semi-annual or annual follow-up visits for up to 5 years. Gross cumulative pregnancy rates were < 0.6 per 100 women in the first year and < 1.5 in the second year in all countries. Significant differences in cumulative 5-year pregnancy rates were observed between weight groups 40-49 and 50-59 kg and between 50-59 and 60-69 kg body weight but not between 60-69 kg and those > or = 70 kg. Total cumulative discontinuation rates after five years of Norplant implants use ranged from 35.8 to 60.0 per 100 women. Younger age and low parity were associated with a higher discontinuation rate. Cumulative discontinuation rates for menstrual reasons more than doubled between the end of the first year and second year of use in 13 of 17 countries. This analysis and one previous review provide the only comparison of Norplant contraceptive system study results across a wide diversity of countries; thus allowing an appreciation of the range of clinical experience with Norplant implants and the regional differences in that experience. DMPA-SC 104 mg/0.65 mL is a new, low-dose subcutaneous (SC) formulation of Depo-Provera contraceptive injection (150 mg/mL medroxyprogesterone acetate injectable suspension) that provides efficacy, safety and immediacy of onset equivalent to Depo-Provera intramuscular (IM) injection. Two large, open-label, Phase 3 studies assessed the 1-year contraceptive efficacy, safety and patient satisfaction with DMPA-SC administered every 3 months (12-13 weeks). Zero pregnancies were reported in both studies, which included a total of 16,023 woman-cycles of exposure to DMPA-SC and substantial numbers of overweight or obese women. DMPA-SC was well-tolerated and adverse events were similar to those reported previously with Depo-Provera IM. Thus, DMPA-SC offers women a new, highly effective and convenient long-acting contraceptive option.
                Copyright 2004 Elsevier Inc. This study evaluated the impact of weight on efficacy during use of an extended oral contraceptive (OC).
                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.
                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.
                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.
                Copyright © 2012. Published by Elsevier Inc.
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.