Mechanisms that explain the contraceptive action of progestin implants for women

Contraceptive methods in adolescence: a narrative review of guidelines

PURPOSE

Adolescent pregnancy, while recently in decline, remains a matter in need of addressing. Education and counselling are deemed crucial and this review aims at comparing published contraceptive guidelines, thus resolving any surrounding misconceptions.

MATERIALS AND METHODS

Recently published contraception guidelines regarding adolescent pregnancy were retrieved. In particular, guidelines and recommendations from ACOG, RCOG, SOCG, AAP, CPS, NICE, CDC, and WHO were compared and reviewed based on each guideline's method of reporting.

RESULTS

Three categories of contraceptive methods are available for adolescents and recommendations on their initiation should be made based on their efficacy, according to all guidelines. Therefore, long acting reversible contraceptives (LARCs) should be highly recommended as the most effective method (typical use failure rate: 0.05%), followed by short-acting hormonal contraceptives (typical use failure rate: 3-9%). The third contraceptive option includes contraceptives used in the moment of intercourse and displays the lowest effectiveness (typical use failure rate: 12-25%), mostly due to its dependence on personal consistency, however offers protection against STI transmission.

CONCLUSION

Adolescents should be encouraged to initiate contraception, with LARCs being the primary choice followed by short-acting hormonal contraception. However, regardless of the chosen effective contraceptive method, the use of condom is necessary for STI prevention.

Perspective Chapter: Modern Birth Control Methods

This chapter focuses on various modern birth control methods, including combined oral contraceptives, progestogen-only pills, progestogen-only injectables, progestogen-only implants, intrauterine devices, barrier contraceptives, and emergency contraceptive pills. Each contraceptive method is covered in detail, including mechanism of action, effectiveness, health benefits, advantages, disadvantages, risks, and side-effects.

Alternative Insertion Site of Nexplanon: Description of a Case Report and Systematic Review of the Literature

The etonogestrel (ENG) implant is among the most effective reversible contraceptives. It can be a good option for patients with different chronic diseases due to no clinically significant effects on lipid metabolism or liver function. Some limitations in the use of this type of device are represented by social and psychiatric disorders, where the easy accessibility of the device becomes a negative feature. In these patients several cases of self-removal or damage to the device have been reported. We report the successful insertion of the Nexplanon^® device into the scapular region in a young woman with a chronic psychiatric disorder. To verify the presence in the literature of other possible implantation sites, we performed a systematic review of the literature on Pubmed, Google scholar and Scopus from 2000 to 2021 using different combinations of the following terms: (Nexplanon), (contraceptive implant), (insertion). Two manuscripts with three cases were detected. Nexplanon^® was implanted in the upper back. In all cases, there were no complications during the insertions and the follow up demonstrated no side effects with contraceptive efficacy. Our report and review is a further confirmation that the scapular region can become a valid insertion site, maintaining good efficacy and safety of the subcutaneous device.

Etonogestrel contraceptive implant failure in a woman taking rifampin: a case report

Background

The etonogestrel subdermal implant is the most efficacious hormonal contraceptive currently available and provides 99.7% effective contraception. However, similar to other hormonal contraception, its effectiveness is compromised with the use of cytochrome P450 inducing drugs resulting in an unplanned pregnancy. Despite this risk, little is known about the outcome of concomitant use of rifampin and contraceptive implants.

Case presentation

A 24-year-old woman was provided with an etonogestrel implant in September 2018. In July 2020, she was started with rifampin based anti-tuberculosis for tuberculosis of the lymph nodes. In December 2020, she presented to the family planning clinic of St. Paul’s Hospital Millennium Medical college with a diagnosis of failed implant and second-trimester pregnancy at a gestational age of 19 weeks. The etonogestrel implant was removed and the patient was linked to antenatal care follow up.

Conclusion

Concomitant use of hepatic cytochrome P450 enzyme-inducing medications with certain hormonal contraceptives may reduce effectiveness resulting in unintended pregnancy. Women should be given detailed counseling about the potential for drug interactions and a multidisciplinary approach with consultation or referral to reproductive health specialists is crucial for optimal management of women who are at increased risk of contraceptive failure and unintended pregnancy.

Etonogestrel-releasing contraceptive implant in a patient using thalidomide for the treatment of erythema nodosum leprosum: a case report

INTRODUCTION

Thalidomide is an immunomodulatory drug and first choice in the treatment of erythema nodosum leprosum. Given its teratogenic potential, it is essential that an effective contraceptive method is used, especially a long-acting reversible contraceptive (LARC) method. The subdermal etonogestrel (ENG)-releasing implant is an adequate method due to the high effectiveness and long-term use. However, interaction between thalidomide and ENG has not been well documented. Concern arises because thalidomide interacts with cytochrome P450 (CYP450) enzymes that metabolize sexual steroids. AIM: We aimed to study the effectiveness and safety of the ENG-implant in a thalidomide user.

METHODS

Case report of a sexually active 21-year-old patient with both Hansen's disease and leprosy reaction type 2 treated with thalidomide requiring effective contraception. Follow-up was up to 36 months after implant placement.

RESULTS

Contraception with ENG-implant was effective and safe, based on clinical parameters (reduction of menstrual flow and cervical mucus thickening) and laboratory parameters (gonadotropins and sexual steroids).

CONCLUSION

To the best of our knowledge, this is the first case reported which presents a patient in simultaneous use of thalidomide and ENG-implant. Although this case report preliminary supports effectiveness and safety of ENG-implant as a contraceptive option in women using thalidomide, rigorous drug-drug interaction research is needed to better characterize the interaction between thalidomide and the ENG-implant.

DESLORELIN (SUPRELORIN®) USE IN NORTH AMERICAN AND EUROPEAN ZOOS AND AQUARIUMS: TAXONOMIC SCOPE, DOSING, AND EFFICACY

The Association of Zoos and Aquariums Reproductive Management Center (RMC) in the US and the European Association of Zoos and Aquaria Reproductive Management Group (RMG) in Europe monitor efficacy of contraceptive products in participating institutions and use those results to inform contraceptive recommendations. This study used the joint RMC-RMG Contraception Database to analyze efficacy of deslorelin implants (Suprelorin^®), a contraceptive used in a wide range of mammalian taxa. More recently its use has increased in birds and in some reptiles and fish. Deslorelin, a gonadotropin-releasing hormone (GnRH) agonist, stimulates the reproductive system before downregulating receptors on pituitary cells that produce hormones that stimulate gonadal steroids in both males (testosterone) and females (estradiol and progesterone), interrupting sperm production and ovulation, respectively. Nevertheless, it has been used mostly in females. Efficacy has been high in mammals, with failures resulting in offspring in only 1.3% of treated individuals and 0.5% of treatment bouts. The failure rate has been higher in birds, with 14.7% of individuals in 7.2% of bouts producing eggs, perhaps reflecting differences in avian GnRH molecules. Too few reptiles and fish have been treated for meaningful analysis. Although deslorelin appears very safe, a possible exception exists in carnivores, because the stimulatory phase can result in ovulation and subsequent sustained progesterone secretion that may cause endometrial pathology. However, the stimulatory phase can be prevented by treatment with megestrol acetate for 7 d before and 7 d after implant insertion. The two current formulations of Suprelorin are effective for minimums of 6 (4.7 mg) or 12 mo (9.4 mg). The data indicate that Suprelorin is an effective and safe contraceptive option for female mammals, although it may not be effective in males of some mammalian species. Further research is needed to ascertain its usefulness in nonmammalian taxa.

Pharmacokinetics, metabolism and serum concentrations of progestins used in contraception

Many different forms of hormonal contraception are used by millions of women worldwide. These contraceptives differ in the dose and type of synthetic progestogenic compound (progestin) used, as well as the route of administration and whether or not they contain estrogenic compounds. There is an increasing awareness that different forms of contraception and different progestins have different side-effect profiles, in particular their cardiovascular effects, effects on reproductive cancers and susceptibility to infectious diseases. There is a need to develop new methods to suit different needs and with minimal risks, especially in under-resourced areas. This requires a better understanding of the pharmacokinetics, metabolism, serum and tissue concentrations of progestins used in contraception as well as the biological activities of progestins and their metabolites via steroid receptors. Here we review the current knowledge on these topics and identify the research gaps. We show that there is a paucity of research on most of these topics for most progestins. We find that major impediments to clear conclusions on these topics include a lack of standardized methodologies, comparisons between non-parallel clinical studies and variability of data on serum concentrations between and within studies. The latter is most likely due, at least in part, to differences in intrinsic characteristics of participants. The review highlights the importance of insight on these topics in order to provide the best contraceptive options to women with minimal risks.

Menstrual Pattern and Characteristics of One-Rod and Two-Rod Levonorgestrel Implant Users

Introduction

The maternal mortality ratio (MMR) in Indonesia reaches 359 per 100,000 live births. The long-acting reversible contraceptive (LARC) method is an effective contraceptive choice for reducing MMR. The contraceptive implant is one of the LARCs that has low usage due to lack of education about the side effects. This study aims to compare the menstrual pattern and characteristics between one-rod and two-rod levonorgestrel implant users.

Methods

A prospective cohort study was performed in patients at Cipto Mangunkusumo Hospital (RSCM) from March 2016 to May 2018. Subject recruitment was done by consecutive sampling. This study was conducted from March 2016 until May 2019. Statistical analysis was performed on the data using the chi-square test to determine the relationship between menstrual pattern and characteristics, and the use of one-rod or two-rod levonorgestrel implants.

Results

A total of 140 subjects participated in the study, comprising 70 (50%) one-rod users and 70 (50%) two-rod users. In the first month, 32.9% one-rod users experienced amenorrhea, 22.9% experienced shortened menstrual period, 30% experienced normal menstrual period, and 14,2 % experienced lengthened menstrual period. In comparison, in the first month, 41.4% two-rod users experienced amenorrhea, 15.7% experienced shortened menstrual period, 32.9% experienced normal menstrual period, and 10% experienced lengthened menstrual period. There was no significant difference in menstrual patterns and characteristics between one-rod and two-rod levonorgestrel implant users.

Conclusion

There was no significant difference in menstrual patterns and characteristics between one-rod and two-rod levonorgestrel implant users. Implications. Menstrual patterns and characteristics from levonorgestrel implants user can help clinicians to reduce discontinuation rate from the acceptors. Further research should be conducted to know other side effects aside from menstrual bleeding patterns.

A rodent model of human dose-equivalent progestin-only implantable contraception

BACKGROUND

Long-acting, reversible contraceptives (LARC; progestin only) are an increasingly common hormonal contraceptive choice in reproductive aged women looking to suppress ovarian function and menstrual cyclicity. The overall objective was to develop and validate a rodent model of implanted etonogestrel (ENG) LARC, at body size equivalent doses to the average dose received by women during each of the first 3 years of ENG subdermal rod LARC use.

METHODS

Intact, virgin, female Sprague-Dawley rats (16-wk-old) were randomized to 1 of 4 groups (n = 8/group) of ENG LARC (high-0.30μg/d, medium-0.17μg/d, low-0.09μg/d, placebo-0.00μg/d) via a slow-release pellet implanted subcutaneously. Animals were monitored for 21 days before and 29 days following pellet implantation using vaginal smears, ultrasound biomicroscopy (UBM), saphenous blood draws, food consumption, and body weights. Data were analyzed by chi-square, non-parametric, univariate, and repeated measures 2-way ANOVA.

RESULTS

Prior to pellet implantation there was no difference in time spent in estrus cycle phases among the treatment groups (p > 0.30). Following pellet implantation there was a dose-dependent impact on the time spent in diestrus and estrus (p < 0.05), with the high dose group spending more days in diestrus and fewer days in estrus. Prior to pellet insertion there was not an association between treatment group and estrus cycle classification (p = 0.57) but following pellet implantation there was a dose-dependent association with cycle classification (p < 0.02). Measurements from the UBM (ovarian volume, follicle count, corpora lutea count) indicate an alteration of ovarian function following pellet implantation.

CONCLUSION

Assessment of estrus cyclicity indicated a dose-response relationship in the shift to a larger number of acyclic rats and longer in duration spent in the diestrus phase. Therefore, each dose in this model mimics some of the changes observed in the ovaries of women using ENG LARC and provides an opportunity for investigating the impacts on non-reproductive tissues in the future.

Ovarian stimulation for fertility preservation in an oncology patient with etonogestrel implant in place

PURPOSE

To describe a case of a young woman who presented for fertility preservation and underwent ovarian stimulation with an etonogestrel implant in place.

METHODS

A 24-year old, gravida 0, with an etonogestrel implant and newly diagnosed lower extremity sarcoma and DVT desiring oocyte cryopreservation prior to adjuvant chemotherapy and radiation. To avoid delay in her oncologic care and allow for continued use of contraception post-retrieval, the patient underwent controlled ovarian hyperstimulation (COH) without removal of the etonogestrel implant.

RESULTS

Baseline labs included follicle-stimulating hormone 9 mIU/mL, luteinizing hormone 4.9 mIU/mL, estradiol 42 pg/mL, anti-Müllerian hormone 5.1 ng/mL, and antral follicle count greater than 40. The patient was placed on an antagonist protocol and stimulated with 125 IU Gonal-F and 75 IU Menopur. She received a total of 12 days of gonadotropin stimulation. On the day of trigger, her estradiol was 1472 pg/mL, lead follicle 21.5 mm with a total of 25 follicles measured > 12 mm. She was triggered with 5000 U hCG. She had a total of 23 oocytes retrieved, 17 of which were metaphase II and vitrified.

CONCLUSIONS

COH and successful oocyte cryopreservation can be achieved in patients with an etonogestrel implant in situ without apparent detrimental effects to oocyte yield or maturity. Due to the etonogestrel implant's inhibitory effects on LH, it is recommended to use an hCG trigger for final oocyte maturation.

Breast Cancer Risk with Progestin Subdermal Implants: A Challenge in Patients Counseling

There is a steady global rise in the use of progestin subdermal implants, where use has increased by more than 20 times in the past two decades. BC risk has been reported with the older progestin only methods such as oral pills, injectables, and intrauterine devices, however, little is known about the risk with subdermal implants. In this review, we aim to update clinicians and researchers on the current evidence to support patient counseling and to inform future research directions. The available evidence of the association between the use of progestin subdermal implants and BC risk is discussed. We provide an overview of the potential role of endogenous progesterone in BC development. The chemical structure and molecular targets of synthetic progestins of relevance are summarized together with the preclinical and clinical evidence on their association with BC risk. We review all studies that investigated the action of the specific progestins included in subdermal implants. As well, we discuss the potential effect of the use of subdermal implants in women at increased BC risk, including carriers of BC susceptibility genetic mutations.

Contraception for the Cardiac Patient: a Cardiologist’s Primer

Purpose of review

Cardiovascular disease (CVD) is the number one cause of maternal mortality in the USA. There are many cardiac conditions which pose significant risk to maternal health, and these women should be offered options to avoid unwanted pregnancies. Individualized contraceptive counseling focusing on woman’s desire for future pregnancy, comorbid conditions, and desire for hormone or non-hormonal (contraceptive) options is paramount to avoid adverse or unwanted side effects. The purpose of this review is to give general guidance on prescribing both hormonal and non-hormonal contraceptives for providers caring for women with heart disease.

Recent findings

Specific recommendation for the use of either non-hormonal or hormonal contraception requires knowledge of the types of contraceptive options available, cost, failure rates, and contraindications to use. Newer progestin-only options have become available and should be considered first-line therapy for women with cardiovascular disease.

Summary

The physiologic burden of pregnancy on the cardiovascular system can cause significant maternal morbidity and mortality for women with underlying CVD. These women should be offered safe and effective options for birth control, and both cardiology and obstetrical providers alike should possess fundamental knowledge of appropriate options.

Long-acting contraception in adolescents and young women with type 1 and type 2 diabetes

Adolescent pregnancy is a major public health problem worldwide. Adolescents living with diabetes are not aware of the risks of unplanned pregnancy and the high rate of fetal and maternal complications when gestation occurs in women with significant hyperglycemia. These data highlight the significance of pregnancy prevention in young women with diabetes. Long-acting reversible contraceptives (LARCs), which include subdermal progestin implants and hormonal and nonhormonal intrauterine devices (IUDs), have been recommended by the American College of Obstetricians Gynecologists and the American Academy of Pediatrics as a first-line contraceptive option for adolescents and young women. This article reviews LARC options for adolescents and young women with type 1 (T1D) and type 2 (T2D) diabetes as well as the possible complications and side effects.

Early embryo-maternal communication in the oviduct: A review

An intact embryo-maternal communication is critical for the establishment of a successful pregnancy. To date, a huge number of studies have been performed describing the complex process of embryo-maternal signaling within the uterus. However, recent studies indicate that the early embryo communicates with the oviductal cells shortly after fertilizationand that this is important for the successful establishment of pregnancy. Only if the early embryo is capable to signal the mother within a precise timeframe and to garner a response, will the embryo be able to survive and reach the uterus. This review will give an overview of all the experimental designs which have investigated embryo-maternal interaction in the oviduct. In addition to that, it will provide a comprehensive analysis of the findings to date elucidating the morphological and molecular changes in the oviduct which are induced by the presence of the early embryo highlighting how the tubal responses affect embryo development and survival.

Mechanistic model of hormonal contraception

Contraceptive drugs intended for family planning are used by the majority of married or in-union women in almost all regions of the world. The two most prevalent types of hormones associated with contraception are synthetic estrogens and progestins. Hormonal based contraceptives contain a dose of a synthetic progesterone (progestin) or a combination of a progestin and a synthetic estrogen. In this study we use mathematical modeling to understand better how these contraceptive paradigms prevent ovulation, special focus is on understanding how changes in dose impact hormonal cycling. To explain this phenomenon, we added two autocrine mechanisms essential to achieve contraception within our previous menstrual cycle models. This new model predicts mean daily blood concentrations of key hormones during a contraceptive state achieved by administering progestins, synthetic estrogens, or a combined treatment. Model outputs are compared with data from two clinical trials: one for a progestin only treatment and one for a combined hormonal treatment. Results show that contraception can be achieved with synthetic estrogen, with progestin, and by combining the two hormones. An advantage of the combined treatment is that a contraceptive state can be obtained at a lower dose of each hormone. The model studied here is qualitative in nature, but can be coupled with a pharmacokinetic/pharamacodynamic (PKPD) model providing the ability to fit exogenous inputs to specific bioavailability and affinity. A model of this type may allow insight into a specific drug's effects, which has potential to be useful in the pre-clinical trial stage identifying the lowest dose required to achieve contraception.

Current Issues and Options for Hormonal Contraception in Adolescents and Young Adult Women With Sickle Cell Disease: An Update for Health Care Professionals

Women with sickle cell disease (SCD) are of particular concern regarding the significantly increased risk of pregnancy-related morbidity, mortality, and adverse outcomes. They have limited knowledge of pregnancy and childbirth risks, as well as of the benefits and risks of contraceptives. Thus, there is an urgent need for appropriate information about reproductive family planning to reduce unintended pregnancy. Any decision regarding the use of contraceptives has to be based on the efficacy and risk/benefit ratio of the method used. Both the World Health Organization (WHO) and the Centers for Disease Control (CDC) have developed, published, and updated evidence-based guidelines for medical providers for the use of contraceptives in patients with specific medical chronic conditions. This article provides an overview of the present knowledge on the use of contraceptives in women with SCD. We believe that the collaboration between health care professionals (hematologists, obstetricians, endocrinologists, and primary care providers) can play a major role in identifying the safer contraceptive method to abolish the risks of unintended pregnancy and preserve the health status of patients with SCD.

Long-acting reversible contraception: A route to reproductive justice or injustice

This article presents information on unintended pregnancies and the ongoing efforts of policy makers to promote long-acting reversible contraception (LARC) to reduce the numbers of such pregnancies. Also discussed is the tension between the encouragement of LARC to promote the public's interests in achieving that goal versus the need to assure that all women can decide about their bodies and reproductive needs. Our discussion includes information, primarily from the United States, on (a) risks associated with unintended pregnancies, (b) LARC devices approved in the United States (copper intrauterine devices (IUDs), hormone IUDs, and implants), (c) public and social benefits of increasing the use of LARC, (d) disadvantages and barriers to using LARC, (e) dangers of promoting LARC in unjust ways, and (f) the meaning of reproductive justice and its connection to social justice. By sharing the information with the audience of this journal, we hope that it will be integrated into clinical work and research on mental health and development. We also hope that experts in those fields will become discussants in the conversation regarding women's reproductive health and social justice that is taking place in the United States and elsewhere.

Responsiveness of the cheetah (Acinonyx jubatus) ovary to exogenous gonadotropins after preemptive oral progestin treatment

Control of ovarian function in cheetahs is sub-optimal, which currently limits the integration of assisted reproductive techniques into the genetic management of that endangered species. The objective of this study was to determine the effect of preemptive progestin treatment on the quality of ovarian responses after exogenous gonadotropin stimulation in cheetahs. Adult females received either 1) 200 IU equine chorionic gonadotropin (eCG) followed with 3,000 IU porcine luteinizing hormone (pLH) (intramuscular route) (n = 5; control group) or 2) similar eCG/pLH administration preceded by a 7-day treatment with oral progestin (0.1 mg/kg altrenogest; ALT group; n = 7). At 42 h post-pLH administration, a series of metrics was assessed via laparoscopy (number of follicles ≥ 2 mm, number of corpora lutea, oviduct and uterine cornua diameter and overall vascularization). Concentrations of fecal estradiol, progesterone and glucocorticoid metabolites (FEM, FPM, and FGM, respectively) were measured by enzyme immunoassay for 3 wk before ALT treatment (Period 1), 7 d during ovarian suppression period (Period 2), throughout eCG/LH treatment and laparoscopy (Period 3), and 6 wk following laparoscopy (Period 4). Overall, nine out of 12 cheetahs (4/5 in control and 5/7 ALT group) had freshly-formed corpora lutea at the time of laparoscopy. Mean follicle and corpora lutea numbers in the control versus ALT group were not different (P > 0.05). Overall measurements and vascularization scores also did not differ (P > 0.05) among groups. FEM average concentrations increased (P ≤ 0.05) in response to eCG for the ALT-treated females between Periods 2 and 3 and were sustained during Period 4. However, FEM average concentrations did not vary (P > 0.05) for control females throughout Periods 1-4. Post-ovulatory FPM average concentrations (Period 4) did not differ (P > 0.05) between the ALT-treated females and controls. FPM average concentration from both groups increased in Period 4 compared to Periods 1-3 (P ≤ 0.05). Females receiving the ALT treatment also had lower (P ≤ 0.05) FGM metabolite average concentrations than control females during ovarian suppression (suggesting adrenal suppression). Collective results suggest that ovarian response to gonadotropin treatment in the cheetah was improved following oral progestin administration due to the normative increase in estradiol following stimulation for these females compared with control. This treatment should lead to more effective timed assisted reproduction procedures for this species.

Use of Long-Acting Reversible Contraception (LARC) and the Depo-Provera Shot in Adolescents

The intrauterine devices (IUDs) and the subdermal implant, collectively known as long-acting reversible contraceptives (LARC), along with the Depo-Provera shot, represent highly efficacious methods of birth control for all reproductive-age women, including adolescents. They are also safe, private, and convenient, and can be used for their noncontraceptive benefits. Additionally, LARC and Depo-Provera represent methods of contraception that do not contain estrogen and may be safely used in young women who have contraindications to estrogen-containing medications. The LARC methods have traditionally been underused by adolescents due to lack of knowledge and misperceptions about safety and effects on future fertility. However, studies have found that when barriers to the use of LARC are removed, adolescents have increasingly chosen the IUD and implant for birth control and most continue to use these methods with satisfaction. This chapter will provide an overview of IUDs, the subdermal implant and Depo-Provera, address barriers to care for adolescents, efficacy, continuation rates, common side effects and reasons for discontinuation, contraindications, and noncontraceptive benefits.

Pharmacophore modeling for identification of anti-IGF-1R drugs and in-vitro validation of fulvestrant as a potential inhibitor

Insulin-like growth factor 1 receptor (IGF-1R) is an important therapeutic target for breast cancer treatment. The alteration in the IGF-1R associated signaling network due to various genetic and environmental factors leads the system towards metastasis. The pharmacophore modeling and logical approaches have been applied to analyze the behaviour of complex regulatory network involved in breast cancer. A total of 23 inhibitors were selected to generate ligand based pharmacophore using the tool, Molecular Operating Environment (MOE). The best model consisted of three pharmacophore features: aromatic hydrophobic (HyD/Aro), hydrophobic (HyD) and hydrogen bond acceptor (HBA). This model was validated against World drug bank (WDB) database screening to identify 189 hits with the required pharmacophore features and was further screened by using Lipinski positive compounds. Finally, the most effective drug, fulvestrant, was selected. Fulvestrant is a selective estrogen receptor down regulator (SERD). This inhibitor was further studied by using both in-silico and in-vitro approaches that showed the targeted effect of fulvestrant in ER+ MCF-7 cells. Results suggested that fulvestrant has selective cytotoxic effect and a dose dependent response on IRS-1, IGF-1R, PDZK1 and ER-α in MCF-7 cells. PDZK1 can be an important inhibitory target using fulvestrant because it directly regulates IGF-1R.

Occurrence of anembryonic pregnancy with use of levonorgestrel subdermal implant (JADELLE®): a case report

BACKGROUND

Progestin-only subdermal implants are one of the most effective contraceptive methods. Anembryonic pregnancy is not reported as a possible outcome in cases of contraceptive failure of these products. We present a rare case of anembryonic pregnancy occurring in a woman with levonorgestrel-releasing implant (JADELLE®).

CASE PRESENTATION

A 31-year-old Cameroonian (black African) housewife with a JADELLE® implant for 13 months, consulted at our hospital for a 1-month history of pelvic pain, prolonged menstrual bleeding, and spotting. She had a last normal menstrual period 8 weeks 1 day prior to presentation. On examination, there was suprapubic tenderness and blood trickling from her cervix. Despite a negative qualitative urine pregnancy test, an empty intrauterine gestational sac with mean sac diameter of 28 mm was visualized on pelvic ultrasound. Dilation and curettage with suction was done and she had complete relief from symptoms.

CONCLUSION

This case report highlights the possibility of anembryonic pregnancy occurring in women using the levonorgestrel-releasing subdermal implant (JADELLE®).

Extended Effectiveness of the Etonogestrel-Releasing Contraceptive Implant and the 20 µg Levonorgestrel-Releasing Intrauterine System for 2 Years Beyond U.S. Food and Drug Administration Product Labeling

Recently published evidence from 2 large studies find that the duration of effectiveness of the etonorgestrel-releasing contraceptive implant to be at least 5 years (compared with the current 3-year label), and for the 20 µg levonorgestrel-releasing intrauterine system at least 7 years (compared with the current 5-year label).

Practice Bulletin No. 186: Long-Acting Reversible Contraception: Implants and Intrauterine Devices

Intrauterine devices and contraceptive implants, also called long-acting reversible contraceptives (LARC), are the most effective reversible contraceptive methods. The major advantage of LARC compared with other reversible contraceptive methods is that they do not require ongoing effort on the part of the patient for long-term and effective use. In addition, after the device is removed, the return of fertility is rapid (1, 2). The purpose of this Practice Bulletin is to provide information for appropriate patient selection and evidence-based recommendations for LARC initiation and management. The management of clinical challenges associated with LARC use is beyond the scope of this document and is addressed in Committee Opinion No. 672, Clinical Challenges of Long-Acting Reversible Contraceptive Methods (3).

Safety of hormonal contraception for obese women

INTRODUCTION

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

Canadian Contraception Consensus (Part 3 of 4): Chapter 8 - Progestin-Only Contraception

OBJECTIVE

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

OUTCOMES

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

EVIDENCE

Published literature was retrieved through searches of Medline and The Cochrane Database from January 1994 to January 2015 using appropriate controlled vocabulary (e.g., contraception, sexuality, sexual health) and key words (e.g., contraception, family planning, hormonal contraception, emergency contraception). Results were restricted to systematic reviews, randomized control trials/controlled clinical trials, and observational studies published in English from January 1994 to January 2015. Searches were updated on a regular basis in incorporated in the guideline to June 2015. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALUES

The quality of the evidence in this document was rated using the criteria described in the Report of the Canadian Task Force on Preventive Health Care (Table 1). CHAPTER 8: PROGESTIN-ONLY CONTRACEPTION: Summary Statements Recommendations.

Investigating Potential Effects of the Contraceptive Implanon on the Behavior of Free-Ranging Adult Female Barbary Macaques

In recent years, the use of hormonal contraception in captive, free-ranging, and wild mammal populations has increased, but the effects on these nonhuman animals' behavior and the associated welfare impacts remain poorly understood. This study of free-ranging adult female Barbary macaques (Macaca sylvanus) at Trentham Monkey Forest compared females implanted with the progestin-only contraceptive Implanon to those not receiving contraception. Females with contraceptive implants had higher rates of self-scratching and spent more time self-grooming (2 behavioral indexes of anxiety) than those without implants. They also directed more aggression at others, spent more time receiving grooming and traveling, and spent less time giving grooming and resting. No significant differences between the 2 groups of females were seen for time spent foraging. These results suggest that Implanon had a number of effects on Barbary macaques, although these need to be considered in light of the significant benefits afforded by the use of this contraceptive. The findings of this study provide important information to those evaluating the relative welfare costs and benefits of alternative methods of population control in this and other species.

The use of a synthetic progesterone, levonorgestrel (LNG), to control the oestrous cycle in the koala

This study investigated the efficacy of a synthetic progestogen, levonorgestrel (LNG), to control koala ovarian activity for the purposes of oestrous synchronisation. Captive koalas were administered either saline control or a 70-mg LNG implant on Day 2 of oestrus. Urogenital cytology, oestrous behaviour and plasma oestradiol-17β and LH concentrations were monitored over a 6-week period. After LNG implant removal females were monitored to determine if the return to oestrus was synchronised. LNG-treated koalas immediately ceased displaying oestrous behaviour, showed no evidence of cornified epithelial cells in smears of urogenital cytology and exhibited low plasma oestradiol-17β concentrations throughout the implantation period. In contrast, oestradiol-17β levels in control koalas showed evidence of continued cyclic activity associated with behavioural oestrus and increased cornified epithelial cells in urogenital smears on Days 33 to 35 after saline injection. After implant removal, LNG-treated koalas exhibited oestrus at 13, 14, 17 and 30 days after implant removal. Plasma LH concentrations varied throughout the study period with no significant time (P = 0.49) or treatment (P = 0.13) effect. Overall results from this study suggest that LNG implants in koalas can inhibit oestrous behaviour and reduce circulating oestradiol-17β levels before oestrus, most likely by preventing development of the pre-ovulatory follicle. However, there was no evidence of LH suppression by the LNG implants. Removal of LNG implants resulted in the synchronous return to oestrus in three of the four treated koalas. Further studies on a larger population are required to validate these findings.

Hormonal contraceptive use in HIV-infected women using antiretroviral therapy: A Systematic review

BACKGROUND

While extensive research has explored pharmacokinetic interactions between antiretroviral therapy and hormonal contraception, few studies have examined whether these interactions affect clinical outcomes. To address this gap, we conducted a systematic review of the literature that describes hormonal contraceptive among HIV infected women who also antiretroviral therapy, focusing on papers that address clinically important outcomes such as pregnancy or ovulation.

METHODS

An electronic literature search was conducted of PUBMED and OVID to identify all articles that addressed hormonal contraception co-administered with antiretroviral therapy published in English between 01 January 1990 and 30 October 2014. In addition, manual reference checks of all articles of interest were conducted to identify articles not captured in the electronic search. Our search criteria identified 405 records. The title and abstract of data reports retrieved via the search were reviewed to identify potential articles of interest. Those with any indication of the main outcomes of interest were considered for inclusion (N=162). Abstracts were then reviewed to identify those manuscripts that would merit a review of the full text version (N=64). Eight articles that addressed the outcomes of interest were identified. The Newcastle-Ottawa Scale was used to assess the quality of these articles.

RESULTS

The studies reviewed were limited in a number of ways that precluded their providing a rigorous assessment of the efficacy of contraception when co-administered with antiretroviral therapy.

DISCUSSION

None of the studies were of adequate quality to provide the guidance that providers and HIV infected women need when considering contraceptive options. High quality, well-powered studies are required to address the efficacy of hormonal contraception when co-administered with antiretroviral therapy.

Sino-implant (II)® continuation and effect of concomitant tenofovir disoproxil fumarate-emtricitabine use on plasma levonorgestrel concentrations among women in Bondo, Kenya

OBJECTIVE

The objective was to assess associations between tenofovir disoproxil fumarate-emtricitabine (TDF-FTC) exposure and levonorgestrel (LNG) concentrations among Kenyan HIV prevention trial participants using Sino-implant (II) LNG implants for contraception.

METHODS

Women were offered implants among other contraceptive methods, were randomized to daily TDF-FTC or placebo, and followed monthly up to 56weeks. Associations between TDF-FTC exposure and mean LNG values were analyzed with linear mixed models.

RESULTS

Of 739 women, 29 (3.9%) received implants with no incident pregnancies and one discontinuation. Mean LNG concentrations over 56weeks among 28 women contributing data ranged between 214.0 and 659.8pg/mL with no significant difference between TDF-FTC and placebo arms or between variable levels of TDF-FTC adherence.

CONCLUSION

Concomitant TDF-FTC use was not associated with a significant change in plasma LNG concentrations among women using Sino-implant (II) in the first year of use.

Metabolic effects of the contraceptive skin patch and subdermal contraceptive implant in Mexican women: a prospective study

Background

The contraceptive skin patch (CSP) accepted by the U.S. FDA in 2001 includes ethinylestradiol and norelgestromine, whereas the subdermal contraceptive implant (SCI) has etonogestrel and is also approved by the FDA. In Mexico, both are now widely used for contraception but their effects on Mexican population are unknown. The objective of the study was to evaluate if these treatments induce metabolic changes in a sample of indigenous and mestizo Mexican women.

Methods

An observational, prospective, longitudinal, non-randomized study of women between 18 and 35 years of age assigned to CSP or SCI. We performed several laboratory tests: clinical chemistry, lipid profile, and liver and thyroid function tests. Also, serum levels of insulin, C-peptide, IGF-1, leptin, adiponectin, and C reactive protein were assayed.

Results

Sixty-two women were enrolled, 25 used CSP (0 indigenous; 25 mestizos) and 37 used SCI (18 indigenous; 19 mestizos). Clinical symptoms were relatively more frequent in the SCI group. Thirty-four contraceptive users gained weight without other clinical significant changes. After 4 months of treatment, significant changes were found in some biochemical parameters in both treatment groups. Most were clinically irrelevant. Interestingly, the percentage of users with an abnormal atherogenic index diminished from 75% to 41.6% after follow-up.

Conclusions

The CSP slightly modified the metabolic variables. Most changes were nonsignificant, whereas for SCI users changes were more evident and perhaps beneficial. Results of this attempt to evaluate the effects of contraceptives in mestizo and native-American populations show that clinical symptoms are frequent in Mexican users of CSP and SCI. Although these medications may affect some metabolic variables, these changes seem clinically irrelevant. Induction of abnormalities in other physiological pathways cannot be ruled out.

Oral progestin priming increases ovarian sensitivity to gonadotropin stimulation and improves luteal function in the cat

As the only domesticated species known to exhibit both induced and spontaneous ovulation, the cat is a model for understanding the nuances of ovarian control. To explore ovarian sensitivity to exogenous gonadotropins and the influence of progestin priming, we conducted a study of queens that were down-regulated with oral progestin or allowed to cycle normally, followed by low or high doses of equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG). Our metrics included 1) fecal steroid metabolite profiles before and after ovulation induction, 2) laparoscopic examination of ovarian follicles and corpora lutea (CL) on Days 2 and 17 (Day 0 = hCG administration), and 3) ovariohysterectomy (Day 17) to assess CL progesterone concentrations, morphometrics, and histology. Reproductive tracts from time-matched, naturally mated queens (n = 6) served as controls. Every progestin-primed cat (n = 12) produced the desired response of morphologically similar, fresh CL (regardless of eCG/hCG dose) by Day 2, whereas 41.7% of unprimed counterparts (n = 12) failed to ovulate or had variable-aged CL suggestive of prior spontaneous ovulation (P < 0.05). The ovarian response to low, but not high, eCG/hCG was improved (P < 0.05) in primed compared to unprimed cats, indicating increased sensitivity to gonadotropin in the progestin-primed ovary. Progestin priming prevented hyperelevated fecal steroid metabolites and normalized CL progesterone capacity, but only when combined with low eCG/hCG. However, priming failed to prevent ancillary CL formation, smaller CL mass, or abnormal luteal cell density, which were common to all eCG/hCG-treated cats. Thus, the domestic cat exposed to eCG/hCG produces CL with structural and functional aberrations. These anomalies can be partially mitigated by progestin priming, possibly due to a protective effect of progestin associated with enhanced ovarian sensitivity to gonadotropins.

A multicenter randomized clinical trial of one-rod etonogestrel and two-rod levonorgestrel contraceptive implants with nonrandomized copper-IUD controls: methodology and insertion data

BACKGROUND

Comparative data on etonogestrel and two-rod levonorgestrel contraceptive implants are lacking.

STUDY DESIGN

A multicenter, open, parallel-group trial with random allocation of implants was performed. For every second implant user, an age-matched woman choosing an intrauterine device (IUD) (TCu380A) was admitted. Methods and data on implant/IUD insertion and 6-week follow-up are reported.

RESULTS

A total of 2008 women were randomized to an implant, and 974 women were enrolled in the IUD group. Results from 997 etonogestrel implant users, 997 levonorgestrel implant users and 971 IUD users were analyzed. In the etonogestrel and levonorgestrel groups, respectively, mean insertion durations were 51 (SD 50.2) s and 88 (SD 60.8) s; complication rates at insertion were 0.8% and 0.2%; and at follow-up, 27.2% and 26.7% of women, respectively, had signs or symptoms at the insertion site. At follow-up within 6 weeks after insertion, all implants were in situ, while 2.1% of IUDs were expelled.

CONCLUSION

Performance of etonogestrel and levonorgestrel implants at insertion and within the first 6 weeks is similar. Short-term (6 weeks) continuation rates appear higher for implants than TCu380A.

Adolescent contraception: review and guidance for pediatric clinicians

The objectives of this article are to review current contraceptive methods available to adolescents and to provide information, guidance, and encouragement to pediatric clinicians to enable them to engage in informed up-to-date interactions with their sexually active adolescent patients. Pregnancy prevention is a complex and dynamic process, and young people benefit from having a reliable authoritative source for information, counseling, and support. Clinicians who provide services for adolescents have a responsibility to develop their skills and knowledge base so that they can serve as that source. This review begins with a discussion about adolescent sexuality and pregnancy in the context of the adolescent developmental stages. We discuss approaches to introduce the topic of contraception during the clinic visit and contraceptive counseling techniques to assist with the discussion around this topic. In addition, information is included regarding confidential services, support of parental involvement, and the importance of male involvement in contraception. The specific contraceptive methods are reviewed in detail with the adolescent patient in mind. For each method, we discuss the mechanism of action, efficacy, contraindications, benefits and risks from the medical perspective, advantages and disadvantages from the patient's perspective, side effects, patient adherence, patient counseling, and any medication interactions. Furthermore, we have included a section that focuses on the contraceptive management for the adolescent patient with a disability and/or chronic illness. The article concludes with an approach to frequently asked or difficult questions. This section largely summarizes subsections on specific contraceptive methods and can be used as a quick reference on particularly challenging topics. Finally, a list of useful contraceptive management resources is provided for both clinicians and patients.

Nexplanon: the new implant for long-term contraception. A comprehensive descriptive review

Nexplanon(®) is a new long-term reversible contraception method. The current review is aimed to analyze the published data concerning the contraceptive effectiveness of Nexplanon(®) and its effects on reproductive function. Pharmacological properties and technical procedures of insertion and removal, as well as the efficacy and safety data available, were discussed. Possible strategies for treating Nexplanon(®)-related bleeding were also described. With regard to the future research and the future scientific developments of contraceptive implants, the possible use of Nexplanon(®) wide-ranging for the symptomatic treatment of endometriosis and premenstrual syndrome (PMS) were considered. Finally, it was defined in which women the use of Nexplanon(®) is indicated and in which it is contra-indicated.

The synthetic progestogen, Levonorgestrel, but not natural progesterone, affects male mate calling behavior of Xenopus laevis

Worldwide, more than 100 million women use hormonal contraceptives, which act through progestogenic modes of action. These man-made hormones can enter the aquatic environment as they are excreted via feces and urine. Xeno-progestins are able to interfere with the endocrine system of female aquatic vertebrates impairing oogenesis and reproduction. However, data on progestogenic effects on reproductive behavior of male aquatic vertebrates are lacking. To evaluate whether progestins affect the mating behavior of male Xenopus laevis, we exposed male frogs to three environmentally relevant concentrations (10(-7) M, 10(-8) M and 10(-10) M) of the synthetic progestin Levonorgestrel (LNG) and the corresponding natural steroid progesterone (PRG), respectively. LNG at all exposure concentrations increased the proportions of advertisement calling, indicating a sexually aroused state of the males. Furthermore LNG at 10(-7) M decreased the relative proportions of rasping, a call type indicating a sexually unaroused state of the male. PRG, on the other hand, did not affect any of those parameters. Temporal and spectral features of the advertisement call itself were not affected by any of the two exposure treatments. Since LNG exhibits slight androgenic activity, the results suggest that LNG effects on male mate calling behavior of X. laevis are due to its moderate androgenic but not to its progestogenic activities. However, although males' sexual arousal seems to be enhanced by LNG, the adverse effects of LNG on female reproduction presumably outweigh these enhancing effects and LNG exposure nonetheless might result in reduced reproductive success of these animals.

The synthetic gestagen levonorgestrel impairs metamorphosis in Xenopus laevis by disruption of the thyroid system

Synthetic gestagens, including levonorgestrel (LNG), are active compounds in contraceptives, and several studies report their occurrence in surface waters. However, information about endocrine-disrupting effects in nontarget organisms is scarce. The present study investigated effects of LNG exposure on thyroid hormone-dependent metamorphosis of Xenopus laevis. Premetamorphic X. laevis tadpoles at Nieuwkoop and Faber (NF) stage 48 were exposed in a flow-through culture system to four LNG concentrations (10(-11), 10(-10), 10(-9), and 10(-8)M) over the period of metamorphosis. At NF 58 and 66, tadpoles were examined sex specifically. Developmental time and organismal responses were recorded and correlated with molecular and histopathological endpoints. Exposure to 10(-8)M LNG caused an inhibition of metamorphosis resulting in developmental arrest at early climax stages as giant tadpoles or tailed frogs. In brain-pituitary tissue of NF 58 tadpoles, gene expression of thyroid-stimulating hormone (β-subunit; TSHβ), TH receptor β (TRβ), and deiodinase type 3 (D3) was not changed. Instead, prolactin (PRL) messenger RNA (mRNA) was significantly increased by 10(-9)M LNG in females and by 10(-8)M LNG in both sexes. In NF 66 tadpoles, mRNA levels of TSHβ mRNA were significantly increased in the 10(-9) and 10(-8)M LNG treatment groups indicating a hypothyroid state. No changes of TRβ, D3, and PRL gene expression were detected. Histopathological evaluation of thyroid gland sections revealed no typical sign of hypothyroidism but rather an inactivated appearance of the thyroid. In conclusion, our data demonstrate for the first time a completely new aspect of thyroid system disruption caused by synthetic gestagens in developing amphibians.

Mating skew in Barbary macaque males: the role of female mating synchrony, female behavior, and male-male coalitions

A fundamental question of sexual selection theory concerns the causes and consequences of reproductive skew among males. The priority of access (PoA) model (Altmann, Ann NY Acad Sci 102:338-435, 1962) has been the most influential framework in primates living in permanent, mixed-sex groups, but to date it has only been tested with the appropriate data on female synchrony in a handful of species. In this paper, we used mating data from one large semi-free ranging group of Barbary macaques: (1) to provide the first test of the priority-of-access model in this species, using mating data from 11 sexually active females (including six females that were implanted with a hormonal contraceptive but who showed levels of sexual activity comparable to those of naturally cycling females) and (2) to determine the proximate mechanism(s) underlying male mating skew. Our results show that the fit of the observed distribution of matings with sexually attractive females to predictions of the PoA model was poor, with lower-ranking males mating more than expected. While our work confirms that female mating synchrony sets an upper limit to monopolization by high-ranking individuals, other factors are also important. Coalitionary activity was the main tactic used by males to lower mating skew in the study group. Coalitions were expressed in a strongly age-related fashion and allowed subordinate, post-prime males to increase their mating success by targeting more dominant, prime males. Conversely, females, while mating promiscuously with several males during a given mating cycle, were more likely to initiate their consortships with prime males, thus reducing the overall effectiveness of coalitions. We conclude that high-ranking Barbary macaque males have a limited ability to monopolize mating access, leading to a modest mating skew among them.

Progestin exposure before gonadotropin stimulation improves embryo development after in vitro fertilization in the domestic cat

This study investigated the influence of progestin priming and ovarian quiescence on response to exogenous gonadotropin stimulation in the cat. Because a subpopulation of cats routinely ovulated spontaneously, there also was the opportunity to examine the ovary's reaction to the added impact of endogenously secreted progestagen. Queens were given 1) equine chorionic gonadotropin (eCG) plus human chorionic gonadotropin (hCG) only (control; n = 9 cats), 2) GnRH antagonist (antide) injections followed by eCG and hCG (n = 9), and 3) a progestin implant (levonorgestrel) followed by eCG and hCG (n = 9). Laparoscopy was used to assess ovarian activity and aspirate follicular oocytes that were graded on the basis of morphology. In five cats per treatment, half of the high-quality oocytes were assessed for glucose, pyruvate, and lactate metabolism as well as nuclear maturation. Remaining oocytes were inseminated in vitro, cultured, and examined at 72 h after insemination for cleavage. In the remaining four cats per treatment, all oocytes were inseminated in vitro and assessed at 72, 120, and 168 h after insemination for embryo developmental stage. Cats pretreated with progestin had more follicles and produced more embryos per donor (including at the combined morula/blastocyst stage) than controls or females treated with GnRH antagonist (P < 0.05). There were no differences among groups (P > 0.05) in oocyte carbohydrate metabolism, nuclear maturation metrics, or fertilization success, although there was a tendency toward improvements in all three (P < 0.2) in progestin-treated females. Interestingly, cats that spontaneously ovulated within 60 days of treatment onset also produced more embryos per cat than induced-ovulation counterparts (P < 0.05). Results indicate that prior exposure to exogenous progestin (via implant) or endogenous progestagen (via spontaneous ovulation) improves ovarian responsiveness to gonadotropins in the cat through a mechanism that is independent of the induction of ovarian quiescence.

Levonorgestrel, not etonogestrel, provides contraception in free-ranging koalas

Management of high-density koala (Phascolarctos cinereus) populations is essential because of the browsing damage they inflict on their habitat. We have tested two types of gestagen implant, namely levonorgestrel and etonogestrel, as contraceptives for koalas. Free-ranging female koalas were given either a control, levonorgestrel (70 mg) or etonogestrel (34 or 68 mg) implant before the breeding season. Koalas were monitored every 4–12 weeks for births. Plasma progesterone was measured and a cytological smear of the urogenital sinus was taken. Fertility was high in the control group and the two etonogestrel-treated groups, with approximately 90% of females giving birth. In contrast, no levonorgestrel-treated female produced young during the study. Removal of levonorgestrel implants from six females reversed the contraceptive effect in the next breeding season, whereas the eight females in which the levonorgestrel implants were left in remained infertile for six breeding seasons. Vaginal cytology showed evidence of oestrous cycles during the breeding season in all females from all groups and there was no difference seen in the prevalence of cornified epithelial cells in the oestrous smears. This indirectly suggests that levonorgestrel does not prevent follicular development and oestrous cycling. Plasma progesterone in levonorgestrel-treated females remained low all year, but rose in controls concurrent with the onset of the breeding season. This suggests that levonorgestrel prevents pregnancy by blocking ovulation. Etonogestrel had absolutely no contraceptive effect at the two doses delivered and so is not suitable for controlling koala populations. In contrast, levonorgestrel was effective as a long-term, reversible contraceptive in wild koalas.

Examining the efficacy, safety, and patient acceptability of the etonogestrel implantable contraceptive

Contraceptive implants provide long-acting, highly effective reversible contraception. The etonogestrel implant (ENG implant) is a single rod implant that offers three years of efficacy. The ENG implant was designed to provide contraceptive efficacy by inhibiting ovulation and Pearl Index scores reported for this method are similar to other long-acting reversible contraception as well as similar to sterilization. The implant has been shown to be safe during breast feeding and may improve symptoms of dysmenorrhea and endometriosis. Irregular bleeding patterns can be expected with the device's use and should be addressed in order to decrease rates of discontinuation.