Effectiveness of Norplant implants through seven years: a large-scale study in China

Drug eluting implants in pharmaceutical development and clinical practice

Introduction: Drug eluting implants offer patient convenience and improved compliance through less frequent dosing, eliminating repeated, painful injections and providing localized, site specific delivery with applications in contraception, ophthalmology, and oncology.Areas covered: This review provides an overview of available implant products, design approaches, biodegradable and non-biodegradable polymeric materials, and fabrication techniques with a focus on commercial applications and industrial drug product development. Developing trends in the field, including expanded availability of suitable excipients, development of novel materials, scaled down manufacturing process, and a wider understanding of the implant development process are discussed and point to opportunities for differentiated drug eluting implant products.Expert opinion: In the future, long-acting implants will be important clinical tools for prophylaxis and treatment of global health challenges, especially for infectious diseases, to reduce the cost and difficulty of treating chronic indications, and to prolong local delivery in difficult to administer parts of the body. These products will help improve patient safety, adherence, and comfort.

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 For the initial review, we wrote to investigators to find additional published or unpublished studies.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.

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.

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.

Can we identify women at risk of pregnancy despite using emergency contraception? Data from randomized trials of ulipristal acetate and levonorgestrel

BACKGROUND

Emergency contraception (EC) does not always work. Clinicians should be aware of potential risk factors for EC failure.

STUDY DESIGN

Data from a meta-analysis of two randomized controlled trials comparing the efficacy of ulipristal acetate (UPA) with levonorgestrel were analyzed to identify factors associated with EC failure.

RESULTS

The risk of pregnancy was more than threefold greater for obese women compared with women with normal body mass index (odds ratio (OR), 3.60; 95% confidence interval (CI), 1.96-6.53; p<.0001), whichever EC was taken. However, for obese women, the risk was greater for those taking levonorgestrel (OR, 4.41; 95% CI, 2.05-9.44, p=.0002) than for UPA users (OR, 2.62; 95% CI, 0.89-7.00; ns). For both ECs, pregnancy risk was related to the cycle day of intercourse. Women who had intercourse the day before estimated day of ovulation had a fourfold increased risk of pregnancy (OR, 4.42; 95% CI, 2.33-8.20; p<.0001) compared with women having sex outside the fertile window. For both methods, women who had unprotected intercourse after using EC were more likely to get pregnant than those who did not (OR, 4.64; 95% CI, 2.22-8.96; p=.0002).

CONCLUSIONS

Women who have intercourse around ovulation should ideally be offered a copper intrauterine device. Women with body mass index >25 kg/m(2) should be offered an intrauterine device or UPA. All women should be advised to start effective contraception immediately after EC.

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.

Impact of obesity on gynecology

Rising obesity rates around the world have had a profound impact on female reproductive health. Childhood obesity is associated with early onset of puberty, menstrual irregularities during adolescence and polycystic ovary syndrome. Women of reproductive age with high BMIs have a higher risk of ovulatory problems and tend to respond poorly to fertility treatment. Strategies for fertility control can also be complex since the efficacy and safety of hormonal contraceptives can be compromised by increased body weight. Obesity can aggravate symptoms of pelvic organ prolapse, stress urinary incontinence and increase the risk of endometrial polyps and symptomatic fibroids. Weight reduction enhances reproductive outcomes, diminishes symptoms of urinary incontinence and reduces morbidity following gynecological surgery. Sustained and substantial weight loss is difficult to achieve with the lifestyle and dietary measures that are currently available. A number of pharmacological treatment options are available, and there are emerging data on reproductive outcomes following surgical treatment for obesity.

Contraceptive use by obese women 1 year postpartum

BACKGROUND

Obese women have higher rates of pregnancy complications, making the prevention of unintended pregnancies in this group of particular importance.

STUDY DESIGN

We performed a secondary analysis of data from Active Mothers Postpartum (AMP), a randomized controlled trial aimed at postpartum weight reduction. We assessed contraceptive use among 361 overweight/obese women 12 months postpartum. Logistic regression was used to model the effect of body mass index (BMI) categories on effective contraceptive use (intrauterine, hormonal or sterilization methods) while adjusting for potential confounders including age, race, parity, breastfeeding, education and chronic illness.

RESULTS

Effective contraceptive use was reported by 45% of women. In the multivariable model, women with a BMI >or=35 kg/m(2) were less likely to use effective contraception than women with a BMI <30 kg/m(2) (OR 0.5, 95% CI 0.3-0.8). There was a trend towards less use of effective contraception among women with a BMI 30-34.9 kg/m(2) as compared to women with a BMI <30 kg/m(2).

CONCLUSION

At 12 months postpartum, obese women were less likely to use effective contraceptive methods than overweight women. Although certain contraceptive methods may be preferred over others in this population, providers should reinforce the importance of effective contraception to avoid unintended pregnancies in obese women.

The relationship between body mass index and unintended pregnancy: results from the 2002 National Survey of Family Growth

BACKGROUND

The study was conducted to characterize the relationship between body mass index (BMI) and unintended pregnancy, contraceptive use patterns, and perceived fertility.

METHODS

This study employed a cross-sectional, nationally representative database (2002 National Survey of Family Growth). Unintended pregnancy was compared among BMI groups [normal (<25 m/kg(2)), overweight (25-30 m/kg(2)) and obese (>30 m/kg(2))]. Analyses also evaluated the association between demographic, socioeconomic, behavioral and health-related variables and BMI. Multiple logistic regression with adjustment for sampling design was used to measure associations of interest.

RESULTS

BMI data were available from 6690 nonpregnant women. Of these, 3600 (53.6%) were normal weight, 1643 (25%) were overweight and 1447 (21.4%) were obese. Compared to women with normal BMIs, the risk of unintended pregnancy in the last 5 years did not differ among overweight [adjusted OR 0.95 (95% CI 0.77-1.17)] or obese [adjusted OR 0.87 (95% CI 0.70-1.09)] women. There were no differences in contraceptive use patterns or perceived fertility among BMI groups.

CONCLUSION

Data from the 2002 NSFG do not support an association between obesity and unintended pregnancy.

Contraceptive Implants: An Overview and Update

Contraceptive implants are safe, highly effective, and long-term methods of contraception that are widely applicable to any reproductive-aged woman. Implants require minimal user compliance and are cost-effective. The new single-rod system simplifies insertion and removal, making implants more accessible for both providers and patients. Specifically, progestin-only implants are safe options for various women including adolescents, postpartum, breast-feeding, those who are medically complicated, or those who have contraindications to or intolerance of estrogen-containing contraceptives.

Contraception for Women with Chronic Medical Conditions

Chronic medical conditions can complicate maternal and fetal health during pregnancy, making unintended or mistimed pregnancy problematic. The use of highly effective reversible contraceptives is important for women with health issues, yet sometimes those same illnesses make the contraceptives themselves less effective or less safe. We review the evidence surrounding contraceptive use by women with six common medical conditions: systemic lupus erythematosus, diabetes mellitus, anticonvulsant use for epilepsy or mood disorder, HIV infection, migraine headache, and obesity. In some instances it is not possible to make a risk-free contraceptive choice, yet pregnancy may be even riskier. Good clinical judgment and patient counseling must be exercised.

Effective use of hormonal contraceptives: Part II: Combined hormonal injectables, progestogen-only injectables and contraceptive implants

Our objective in this systematic review was to evaluate evidence regarding controversial issues in the clinical management of women using injectable and implantable contraceptives. We searched MEDLINE and EMBASE for reports of primary research, published from 1966 through April 2005 in peer-reviewed journals, related to the initiation of combined or progestogen-only injectables and contraceptive implants, the effects of late contraceptive injections or the duration of levonorgestrel implant effectiveness. Results of the studies we reviewed showed that initiating injectable and implantable contraceptives through day 7 of the menstrual cycle suppresses follicular activity. Time to ovulation after study participants discontinued using injectables varied widely: from 4 to 8 weeks after the last administration of combined injectables, from 15 to 49 weeks after the last injection of depot medroxyprogesterone acetate and from 5 to 19 weeks after the last injection of norethisterone enanthate. Norplant implants left in place for up to seven completed years remained effective among women who weighed <70 kg at the time of implant insertion, but their effectiveness decreased among women weighing >or=70 kg.

The Association Between Body Weight, Unintended Pregnancy Resulting in a Livebirth, and Contraception at the Time of Conception

OBJECTIVES

Annually, 3 million pregnancies in the United States are classified as unintended, with many of these unintended pregnancies occurring to women who use some type of contraceptive. Obesity may be affecting the biological effectiveness of contraceptives. We investigated whether there is an association between body weight and unintended pregnancy and whether this association differs by a woman's contraceptive status at the time of conception.

METHODS

We conducted a case-control study using multistate data from the 1999 Pregnancy Risk Assessment Monitoring System. A total of 18,445 women provided complete information on pregnancy intention, contraceptive use at the time of conception, weight, height, and other covariates. Multivariable logistic regression was used to obtain odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Among contraceptors, overweight and obese women had nearly twice the odds of having an unintended pregnancy as compared to women with normal body mass indices (OR=1.73 [95% CI: 1.20, 2.36] and OR=1.75 [95% CI: 1.21, 2.52], respectively) after adjustment for age, marital status, education, socioeconomic status, Medicaid, race/ethnicity, and parity. No association was found between heavier weight and unintended pregnancy among noncontraceptors.

CONCLUSIONS

Though the observed associations could be the result of selection bias or unmeasured confounding, the findings suggest that the effect of obesity on unintended pregnancy is limited to contraceptive failure. Prospective studies designed specifically to examine a body weight-contraceptive failure association are needed to determine if heavier women should be advised to use contraceptive methods other than hormonal contraceptives to prevent unintended pregnancy.

The Role of Body Weight in Oral Contraceptive Failure: Results from the 1995 National Survey of Family Growth

PURPOSE

Many unintended pregnancies occur in women who use contraception. We conducted this study to determine if increasing body weight is associated with oral contraceptive (OC) failure.

METHODS

This retrospective cohort study consists of the 1916 women who reported using OCs in January 1993 and provided complete covariate information on the 1993 National Health Interview Survey and 1995 National Survey of Family Growth. Body weight and body mass index (BMI) were self-reported in 1993. The outcome was defined to be any conception occurring in women reporting OC use during the month of conception. Cox proportional hazards models were used to model the body weight/BMI-OC failure association.

RESULTS

Women with a BMI >/= 30 had a statistically significant increased risk of having an OC failure as compared to women with BMIs of 20 to 24.9 (HR=1.80, 95% CI, 1.01, 3.20). However, after adjustment for age, marital status, education, poverty, race/ethnicity, parity, and dual method use, this increased risk was attenuated and no longer statistically significant (HR=1.51, 95% CI, 0.81, 2.82). Increasing body weight was not associated with an increased risk of OC failure in the unadjusted or adjusted models.

CONCLUSIONS

We did not find a strong or statistically significant association between increasing body weight/BMI and OC failure among this population of women. Prospective studies specifically designed to examine this association are needed to determine if heavier women should be advised to use a contraceptive method other than OCs to prevent pregnancy.

Role of progestins in contraception

Progestins have been used for contraception for more than 30 years. The main goal was to develop a contraceptive method devoid of the metabolic or clinical side-effects associated with the use of estrogens. The development of new contraceptive methods and formulations is time-consuming and requires devotion, belief, and also strong economical basis. As a result of this endeavor new methods have been developed: oral progestins, implants, injectables, intrauterine hormonal systems, and vaginal rings. Progestin-only contraceptives may be preferable in some situations, which have absolute or relative contraindications to estrogen, side-effects to estrogen containing hormonal contraception, lactation, and comfort and feasibility of formulations for long-term use. At present, emergency contraception is also performed with progestin.

Body Mass Index, Weight, and Oral Contraceptive Failure Risk

OBJECTIVE

To estimate the effect of body mass index (BMI) and weight on risk of pregnancy while using oral contraceptives (OCs).

METHODS

We conducted a case-control study of 248 health maintenance organization enrollees who became pregnant while using OCs between 1998 and 2001 and 533 age-matched enrollees who were nonpregnant OC users during the same period. Using logistic regression we calculated adjusted odds ratios (ORs) to estimate the risk of pregnancy according to BMI and weight quartile.

RESULTS

Among all OC users, when compared with women having a BMI of 27.3 or less, the risk of pregnancy was nearly 60% higher in women with BMI greater than 27.3 (OR 1.58, 95% confidence interval [CI] 1.11-2.24) and over 70% higher in women with BMI greater than 32.2 (OR 1.72, 95% CI 1.04-2.82). Among consistent users (women who missed no pills in reference month), the risk of pregnancy was more than doubled in women with BMI greater than 27.3 (OR 2.17, 95% CI 1.38-3.41) or BMI greater than 32.2 (OR 2.22, 95% CI 1.18-4.20). When compared with women weighing 74.8 kg or less, among consistent OC users the risk of pregnancy was over 70% higher in women weighing more than 74.8 kg (OR 1.71, 95% CI 1.08-2.71) and nearly doubled in women weighing more than 86.2 kg (OR 1.95, 95% CI 1.06-3.67).

CONCLUSION

Our results suggest that being overweight may increase the risk of becoming pregnant while using OCs. If causal, this association translates to an additional 2-4 pregnancies per 100 woman-years of use among overweight women, for whom consideration of additional or effective alternative contraceptive methods may be warranted.

Manipulation of the pill-free interval in oral contraceptive pill users: the effect on follicular suppression

OBJECTIVE

The purpose of this study was to compare follicular suppression that was produced by 3 different oral contraceptive regimens that differ by treatment in the pill-free interval.

STUDY DESIGN

In a university setting, 54 women were assigned randomly to receive either 20 microg ethinyl estradiol+100 microg levonorgestrel followed by 7 pill-free days, 20 microg ethinyl estradiol+150 microg desogestrel followed by 2 days of placebo then 10 microg ethinyl estradiol for 5 days, or 28 days of 20 microg ethinyl estradiol plus 150 microg desogestrel. Follicular suppression was evaluated by serial ultrasound scans and by serum and urinary hormone levels during a 2-month study period. Data were analyzed by nonparametric statistical tests.

RESULTS

There was a significant difference in follicle count among the 3 groups (P=.005). Women who were treated with a 7-day pill-free interval experienced the least suppression. Estrogen levels were more variable and led to an observation that overweight (body mass index, >25 kg/m(2)) was associated with reduced follicle suppression (relative risk, 1.6; 95% CI, 1.0, 2.7) and higher estrogen levels (relative risk, 5.3; 95% CI, 1.3, 21).

CONCLUSION

Contraceptive pill users who were treated with a 7-day pill-free interval demonstrated less follicular suppression than women who were supplemented with either estrogen alone or estrogen plus progestin. Overweight women were less suppressed than women of normal weight.

Expanded clinical trial of emergency contraception with 10 mg mifepristone

We conducted a clinical single-arm trial to evaluate the effectiveness of 10 mg mifepristone for emergency contraception (EC) in a large population in China. The participating centers were 31 family-planning clinics and hospitals in the following 19 provinces or municipalities in China: Beijing, Shanghai, Tianjin, Harbin, Changchun, Shengyang, Shijiazhuang, Zhengzhou, Taiyuan, Nanjing, Jinan, Hangzhou, Guangzhou, Wuhan, Changsha, Chongqing, Guiyang, Chengdu, Kunming. A total of 4945 women requesting EC within 120 h after a single act of unprotected intercourse were recruited and treated with 10 mg mifepristone. A total of 28 women were lost to follow-up, and 4917 women were included in the analysis, of whom, 69 became pregnant. The combined pregnancy rate was 1.4 [95% confidence interval (CI): 1.0-1.9] and the percentage of pregnancies prevented was 82.2% (95% CI: 77.5-86.2%). There was a significant inverse trend in pregnancy rate with body mass index that disappeared when adjusted for other variables. The pregnancy risk was double among nulliparous women compared to parous women (2.3% compared to 1.0%), and it increased by a factor of 1.5 when the treatment was administered at 25-48 h and at 49-72 h compared to administration within 24 h, although this association was not significant. The risk of pregnancy was higher if intercourse took place during the follicular or preovulatory phase of the cycle. Women having repeated intercourse after treatment without any contraceptive methods had a dramatic increase in the risk of pregnancy, while those who used contraceptives had similar risk to those without acts. Side effects were mild and present in only small proportions of women: nausea and vomiting in 9% and other side effects in 2-3%. Delay of menstruation of 7 days or more occurred in 6.5% of women. The expanded study confirmed the high efficacy and safety of 10 mg mifepristone for EC.

Risks and benefits, advantages and disadvantages of levonorgestrel-releasing contraceptive implants

Levonorgestrel-releasing implants are long acting contraceptives, approved for 5 years of continuous use. Two marketed systems, the six capsule Norplant use of tradenames is for product identification purposes only and does not imply endorsement. and the two rod Jadelle, have essentially equal rates of drug release, pregnancy and adverse events over 5 years of use. Randomised clinical trials and controlled cohort observations indicate that for the first 3 years, when pregnancy rates are at or almost zero, no other contraceptive system is more effective, although etonogestrel implants provide equal effectiveness. Annual pregnancy rates rise in the fifth year of continuous use but remain below 1 per 100 women. Annual pregnancy rates of Norplant users remain below 1 per 100 throughout 7 years of continuous use. Levonorgestrel implants provide low progestogen doses; 40-50 microg/day at 1 year of use, decreasing to 25-30 microg/day in the fifth year. Serum levels of levonorgestrel at 5 years are 60-65% of those levels measured at 1 month of use. Adverse effects with levonorgestrel implants are similar to those observed with progestogen only and combined oral contraceptives. Risks of ectopic pregnancy, other pregnancy complications and pelvic inflammatory disease are reduced in comparison with those of women using copper or non-medicated intrauterine devices. Risks of developing gallbladder disease and hypertension or borderline hypertension, although small, are about 1.5 and 1.8 times greater, respectively, in women using levonorgestrel implants than in women not using hormonal contraception. Other serious diseases have not been found to occur significantly more frequently in levonorgestrel implant users than in women not using hormonal contraception. The great majority of levonorgestrel implant users experience menstrual problems, but serious bleeding problems are not more frequent than in controls. Other health problems reported more frequently by levonogestrel implant users than by women not using hormonal contraception in a study of 16000 women included skin conditions, headache, upper limb neuropathies, dizziness, nervousness, malaise, minor visual disturbances, respiratory conditions, arthropathies, weight change, anxiety and non-clinical depression. Clinical depression is not more frequent in women using implants compared with those not using hormonal contraception (i.e. using intrauterine devices, sterilisation). Removal problems occur less frequently with Jadelle than with Norplant. The mean removal time for Jadelle is half that of Norplant. Levonorgestrel implants in nationally representative scientific samples, in randomised trials, and in controlled cohort studies have continuation rates as high as or higher than any other reversible contraceptive over a duration of 5 years. This would imply that the satisfaction women derive from the contraceptive effectiveness of levonorgestrel implants greatly outweighs the dissatisfaction that may accompany menstrual disturbances and other adverse effects associated with implants.

Characteristics of menstrual problems associated with Norplant discontinuation: results of a multinational study

This paper presents a secondary analysis of 3419 Norplant users from 11 countries throughout Asia, Africa and Latin America. The main objective was to identify the menstrual problems associated with a high risk of early discontinuation of Norplant use. Eligible participants were divided into two groups: those who continued use (n = 2667) for the first 3 years and those who discontinued use because of bleeding or pain (n = 752) during the first 3 years of use. Menstrual characteristics of the women were compared between groups using a logistic regression model with generalized estimating equations. Flow duration of more than 7 days, excessive amount of flow, dysmenorrhea and intermenstrual bleeding for more than 7 days were associated with a significant risk of discontinuation. The highest risk was observed in association with flow duration of more than 7 days (adjusted odds ratios of 1.85, 2.01 and 2.20 at 1, 2 and 3 years, respectively). The appropriate management of prolonged or excessive bleeding, namely by continuous counseling, is essential for successful Norplant use.

Metabolic effects of implantable steroid contraceptives for women

The metabolic impact of progestin-only contraceptives is less than that of combined oral contraceptives. Subdermal contraceptive implant systems that provide a sustained release of low levels of progestins are now becoming widely available. This review evaluates the metabolic effects of currently available products that release the progestins levonorgestrel (Norplant, Jadelle, and their Chinese equivalents); etonogestrel (Implanon); nomegestrol acetate (Uniplant); and Nestorone, formally called ST-1435 (Nestorone implant/Elcometrine). Data on liver, kidney, and renal function; carbohydrates and insulin release; hemostasis; blood pressure; and lipids are considered. The metabolic effects reported for these methods as a whole were minimal. Any changes were generally within the normal range for the populations studied and, therefore, are unlikely to be of clinical significance. However, all published studies have been conducted in healthy populations of women. To inform clinical practice, the field would be well served to have additional empiric data from well-designed, well-implemented, and well-reported trials in women who are deemed to be at elevated risk for certain diseases including cardiovascular disease and diabetes.

Implantable contraceptives for women: effectiveness, discontinuation rates, return of fertility, and outcome of pregnancies

Progestogen-only contraceptive implants are highly effective. In most studies, 5-year cumulative pregnancy rates are less than 1.5/100 women for Norplant and Norplant II. No study has yet reported any failures with Implanon. Weight over 70 kg and age at insertion under 25 years both increase the failure rate of Norplant and Norplant II; however, data are as yet lacking for Implanon. The effectiveness of other progestogen-only implants for which there are as yet few data are unlikely to be any different. Continuation rates are high compared with other hormonal methods and with the intrauterine device. In most cohorts at least 35% of women, and often many more, are still using Norplant by the end of 5 years. Rates vary according to a number of factors, including population studied, age, and parity. Menstrual disturbance is by far the most common reason for discontinuation, with headache, acne, weight gain, and desire for pregnancy accounting for other common reasons for implant removal. Fertility returns rapidly following implant removal, and pregnancy rates (76-100% 1 year after removal) are usually no different from those following discontinuation of any other contraceptive method. There is no increase in the risk of ectopic pregnancy, fetal malformation, or impaired infant health in pregnancies conceived either during implant use or after removal.

Toxicology of polymers for implant contraceptives for women

This article reviews the toxicology of polymers that are used in contraceptive implants. The two main classes of synthetic, nondegradable polymers used in the delivery of female contraceptives are silicone elastomers (e.g., Silastic) and ethylene co-vinyl acetate (EVA; ELVAX). The controversies surrounding the silicone breast implants have prompted several studies to evaluate the toxicity of silicones. The epidemiologic data obtained thus far have overwhelmingly concluded that no correlation exists between certain chronic symptoms, such as arthritis, in patients and silicone prosthesis. This conclusion has been echoed by the expert panel report by the Institutes of Medicine. Although the IOM report focused on the safety of silicone breast prosthesis, data emerging from the joint reconstruction area also suggests that Silastic is safe for in vivo use. The toxicological studies on EVA are few, and the conclusion thus far is that they elicit no adverse local or systemic response over extended periods in vivo. In conclusion, the prognosis for Silastic and ELVAX as of now is excellent. However, any future implant development using these polymers should place an emphasis on processing parameters to minimize potential small molecule leachants and establish safety as a function of both site and duration of implantation.

Implantable contraception

Although levonorgestrel contraceptive implants have been available for over 15 years, innovations have only recently led to a wider choice. These new implants offer easier insertion and removal and other advantages depending on the type of progestin. Implants prevent pregnancy by several mechanisms, including inhibition of ovulation and luteal function and alteration of cervical mucus and the endometrium. The high efficacy and ease of maintenance make implants an ideal contraceptive for many women, including adolescents, a population that uses implants infrequently but reports high satisfaction. Implants are appropriate for women who are breastfeeding, who have contraindications to estrogen, or who have diseases such as diabetes, hypertension, sickle cell anemia, or an HIV infection because implants have few metabolic or hematologic effects. Long-term use has not been associated with a decrease in BMD and generally leads to increased blood levels and iron stores. Women who wish to space their pregnancies appreciate the nearly immediate onset of action with insertion and the rapid termination of all effects with removal. All types of implants lead to menstrual changes and other side effects in some women. Adverse effects that occur in implant users more than the general population include headaches and acne. Women must be thoroughly counseled regarding the potential for menstrual alteration, side effects, and sexually transmitted infections if they do not use condoms. Despite their initial high cost, implants are a cost-effective method over several years, even when discontinued before the life of the implant.

Prolonged effectiveness of Norplant(R) capsule implants: a 7-year study

Soft tubing Norplant(R) contraceptive implants were studied in 1210 women for 7 years to measure the duration of effectiveness and the magnitude of the pregnancy rates over that time. Mean age at enrollment was 27.4 years. Of the enrollees, 42% were US residents. One-sixth (16.1%) weighed >/=70 kg at the time of implant placement. At the end of 5 years, the cumulative pregnancy rate was 1.1/100; at the end of 7 years, it was 1.9/100. No pregnancies occurred to any of the 400 women who enrolled in the study at age >/=30 years and who weighed <100 kg. Among women aged 18-33 years, the 7-year Norplant pregnancy rates are comparable to the median pregnancy rates of tubal sterilization methods for women of the same age and duration of use. For women aged >/=34 years, without regard to weight at admission, the 7-year effectiveness of soft tubing Norplant equals or surpasses that of tubal sterilization. For continuing implant users, annual pregnancy rates <1.0/100 in years 6 and 7, together with low cumulative pregnancy rates, testify that Norplant capsule implants remain highly effective for 7 years.

A 10-year follow-up study of contraceptive Norplant implants

OBJECTIVES

To evaluate the long-term efficacy and health problems associated with Norplant implants and re-implants after 5 full years of first implants.

METHOD

From 1984 to 1988, 1657 women accepted first implants of Type I and Type II of Norplant, and 394 first acceptors had a re-implant, at a clinic for study. The clinical records and annual follow-up data of acceptors were analyzed. The life-table technique was the main method used.

RESULTS

The continuation rates were very high. The cumulative pregnancy rates at 1, 3 and 5 full years of use were 0.0%, 0.1% and 0.7%, respectively. Users with heavier body weight had higher pregnancy rates. The rate of menstrual disturbances peaked at 73% after 3 months and consistently decreased to 20% at 5 years of use. Rates of menstrual disturbances associated with re-implants were much lower.

CONCLUSION

Norplant is extremely effective and safe for long-term use.

Contraception with two levonorgestrel rod implants. A 5-year study in the United States and Dominican Republic

A 5-year trial of a two-rod contraceptive implant, which releases the progestin levonorgestrel (LNG rod), was conducted at four clinics with 594 women. Mean age and weight at admission were 25.5 years and 62.4 kg, respectively. Consent to continue through 5 years was sought and obtained when the 3-year cumulative pregnancy rate proved to be 0.8 per 100. No pregnancies occurred in the fourth or fifth years. The 5-year cumulative pregnancy rate was, therefore, 0.8 per 100 with an annual average pregnancy rate below 2 per 1000 women. Prolonged bleeding/spotting (8.2% of subjects) and irregular bleeding (5.6%) were the most frequently cited medical reasons for removal. Removals for headache (4.7%) and weight change (4.0%) were the next most frequent medical reasons. Between 1% and 2% of subjects during the 5-year trial sought removals for each of the following conditions: mood changes, lower abdominal pain, depression, or pain at the implant site. The mean annual continuation rate during the study was 77 per 100. Use per woman averaged 2.96 years. Mean removal time was 5.9 +/- 0.6 min. These data indicate that, for a 5-year period, the two LNG rod implants are equivalent to the six Norplant capsule implants with respect to safety and efficacy parameters, but permit easier and more rapid implant removal.

Norplant consensus statement and background review

This review has highlighted the attributes of a very important new method of contraception. The signatories to this document agree that, with the provision of appropriate information and instruction for the user, Norplant is a good contraceptive choice to be made available worldwide in family planning programs that have the resources for appropriate training and counseling. The signatories to this document are acting in their own personal capacity and not as representatives of any particular organization.