Mechanisms that explain the contraceptive action of progestin implants for women

The oestrogen ‘sparing’ effect of implanon: A case report and review

This article presents a case study of the 'oestrogen sparing effect' of etonorgestrel especially high lighting its use in a patient with hypoestrogenism following long-term use of depomedroxyprogesterone acetate (DMPA); still wishing a long-term reversible method of contraception. There are studies demonstrating the effects of both DMPA and etonogestrel on estrogen status, but evidence is sparse, exploring the possibilities of usage of etonorgestrel following demonstration of hypo-oestrogenism with DMPA usage.

The use of depot-medroxyprogesterone acetate in contraception and its potential impact on skeletal health

BACKGROUND

In the fall of 2007, the controversy about the contraceptive use of depot-medroxyprogesterone acetate (DMPA) and its potential impact on skeletal health reached the media in the province of Quebec, Canada, thereby becoming a matter of concern for the lay public and physicians. In order to discuss this subject openly, the National Institute of Public Health of Quebec (INSPQ) organized a scientific meeting on February 15, 2008, with targeted physicians delegated by their medical associations in the fields of general practice, obstetrics and gynaecology, rheumatology, orthopaedic surgery, physiatry and endocrinology.

STUDY DESIGN

Participants reviewed the scientific literature using the study classification method according to the level of evidence, reviewed published guidelines of medical societies and organizations on the subject and reached a consensus position. This manuscript presents a review of the literature and describes the consensus position of the targeted medical associations.

RESULTS

The consensus position adopted by all the targeted medical associations determined that DMPA was a cost-effective contraceptive option that must be considered in the light of the clinical situation and preference of each woman. Candidates for injectable contraception should be informed that the use of DMPA is associated with a slight decrease in bone mineral density (BMD), which is largely, if not completely, reversible. There should not be an absolute limit to the length of time that the DMPA contraceptive is used, regardless of the woman's age. Monitoring BMD is not recommended among users of DMPA for contraceptive purposes. Finally, the consensus statement declared that, although supplements of calcium and vitamin D are beneficial for skeletal health for women in general, such supplementation should not be recommended solely based on a woman's use of DMPA.

CONCLUSION

Given the scientific evidences, DMPA use remains a valid contraceptive option for women. Its potential impact on BMD must be balanced against the significant individual, familial and social consequences of unintended pregnancy.

Hormonal contraception

Hormonal contraceptives have been a part of clinical practice for more than 40 years, and family planning programs, based largely on contraceptive provision, are regarded as one of the most successful public health interventions of the 20th century. Thus, discussion of family planning issues and contraceptive considerations has become an integral component of women's health care and one of the benchmarks of the traditional annual well-women visit. In terms of cost-effectiveness, prevention of unplanned pregnancies through contraceptive use has repeatedly been shown to be a highly cost-effective use of health care dollars. Options for effective hormonal contraception have expanded tremendously and include a variety of delivery options, including the pills both in traditional 21/7 format, and more recently in a 24/4 format, as well as a vaginal ring, a skin patch, implants, and the hormonally medicated intrauterine device. Importantly, the overall risks associated with hormonal contraceptives have been reduced as compared with older formulations, even for women with medical conditions. Many modern hormonal contraceptives also offer valuable noncontraceptive benefits. To help clinical decision making, a number of evidence-based guides have been published, and the American College of Obstetricians and Gynecologists has recently updated their practice bulletin on contraception use in women with medical conditions. In general, clinical protocols for provision of hormonal contraceptives have been streamlined, and unnecessary practices, tests, and procedures are identified and discouraged. In this review, we will summarize both technical and programmatic aspects of hormonal contraceptive use, and methods are discussed in order of efficacy from highest to lowest.

Priming with progestin, but not GnRH antagonist, induces a consistent endocrine response to exogenous gonadotropins in induced and spontaneously ovulating cats

Ovarian sensitivity to exogenous gonadotropin stimulation (equine chorionic gonadotropin [eCG] and human chorionic gonadotropin [hCG]) following pre-treatment with a progestin (levonorgestrel) versus GnRH antagonist (antide) was studied in cats known to be induced versus spontaneous ovulators. Queens were assigned to one of three treatments: (1) levonorgestrel implants+eCG/hCG (n=7 cats); (2) antide injections+eCG/hCG (n=7) or (3) eCG/hCG alone (control; n=7). Hormonal metabolites were assessed in fecal samples collected daily for 60 days before and during the 37 days inhibitory pre-treatment and for more than 60 days after eCG/hCG. Fecal metabolites of estradiol and progesterone were measured by radioimmunoassay. Females that maintained baseline progesterone were considered induced ovulators, whereas cats that exhibited a luteal phase before inhibition treatment were classified as spontaneous ovulators. Based on fecal hormone profiles, levonorgestrel thoroughly inhibited ovarian activity, whereas antide synchronized follicular phases but did not induce complete ovarian down-regulation. Both treatments prevented ovulation in spontaneous ovulators, but neither caused regression of existing corpora lutea (CL). Levonorgestrel, but not antide, pre-treatment resulted in a quiescent ovary at the time of eCG injection, yet endocrine responses to eCG/hCG were not different among treatments. Interestingly, spontaneously ovulating females exhibited a prolonged estradiol response to gonadotropin stimulation compared to induced ovulators, and this prolonged estradiol surge was replicated by levonorgestrel pre-treatment. Thus, the progestin levonorgestrel effectively suppresses follicular and luteal activity in the cat, resulting in a more consistent response to gonadotropin stimulation, even in females prone to spontaneous ovulation.

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.

Endometrial histology, microvascular density and caliber, and matrix metalloproteinase-3 in users of the Nestorone®-releasing contraceptive implant with and without endometrial breakthrough bleeding

OBJECTIVE

This descriptive study evaluated endometrial histology, microvascular density and caliber, and quantification of matrix metalloproteinase (MMP-3) expression in long-term users of the Nestorone (NES)-releasing implant who presented or not endometrial breakthrough bleeding (BTB).

METHODS

Endometrial biopsies were obtained from 32 healthy women with unpredictable BTB. The quantitative analysis was performed only in 20 samples.

RESULTS

The mean duration of use of the implant among the 14 women with BTB was 19.6+/-1.0 months, and the other six women had used the implant for 17.7+/-2.3 months (mean+/-S.E.M.). Histological analysis of the endometrial tissue showed a predominance of progestogenic pattern followed by atrophic and proliferative endometrium in both groups. Mucosal breakdown and glandular pseudostratification were observed in half of the cases. Endometrial vascular density was 73.1+/-10.0 and 57.5+/-24.1 vessels/mm(2), and maximum vessel diameter was 923.3+/-86.0 and 1038.0+/-404 microm (mean+/-S.E.M.) in the group with and without BTB, respectively, without significance, and the rate of cells expressing MMP-3x1000 counted stromal cells was 155.8+/-24.8 and 127.0+/-19.0 (mean+/-S.E.M.) in both groups, respectively, without significance.

CONCLUSIONS

This study provides information about some endometrial aspects of women using NES in contraceptive implants. In addition, the endometrium was similar during long-term use of NES-releasing contraceptive implants in women with and without endometrial bleeding.

Medical eligibility criteria for new contraceptive methods: combined hormonal patch, combined hormonal vaginal ring and the etonogestrel implant

To review evidence on the combined hormonal patch, combined hormonal vaginal ring and the etonogestrel implant, with a focus on safety and effectiveness of use among women with special health conditions, we searched MEDLINE, Pre-MEDLINE and the Cochrane Library for reports published from 1980 through March 2005. Articles eligible for review included 11 on the hormonal patch, nine on the hormonal ring, and 11 on the etonogestrel implant. Limited evidence suggests patch efficacy is lower among women>90 kg. No evidence was identified for vaginal ring use among women with medical conditions. A single small study found that etonogestrel implants had no adverse effects on bone mineral density among women 18-40 years old. Limited evidence also suggests no adverse effects of the etonogestrel implant on lactation parameters or infant development among users enrolled 28 to 56 days postpartum and followed for 4 months.

Short term suppression of follicular recruitment and spontaneous ovulation in the cat using levonorgestrel versus a GnRH antagonist

Suppression and subsequent rebound of ovarian activity using a progestin (levonorgestrel; Norplant) versus a GnRH antagonist (antide) was assessed in the domestic cat via fecal estradiol and progesterone metabolite analyses. Following an initial dose-response trial, queens were assigned to one of four treatments: (1) antide, two 6 mg/kg injections 15 days apart (n = 8 cats); (2) levonorgestrel, six silastic rods (36 mg levonorgestrel/rod) implanted for 30 days (n = 8); (3) control injections (n = 5); and (4) control implants (n = 5). Steroid metabolites were quantified from daily fecal samples for 90 days before, 30 days during, and 90 days after treatment. Antide and levonorgestrel inhibited estrous cyclicity in contrast to continued cyclicity in controls. Cats already at estradiol baseline in antide (n = 7) and levonorgestrel (n = 4) groups remained inhibited during treatment. In females with elevated estradiol levels at treatment onset (Day 0), a normal estradiol surge was completed before concentrations declined to baseline (approximately Days 5-7) and remained suppressed throughout the remaining treatment period. Additionally, 56% of treatment animals exhibited at least one spontaneous ovulation during the pre-treatment period, but no female ovulated during treatment with levonorgestrel or antide. Antide-treated cats exhibited lower (P < 0.05) baseline estradiol concentrations during treatment compared to pre- and post-treatment. In contrast, levonorgestrel induced elevations in baseline estradiol following treatment compared to pre- and during treatment intervals. Control females showed no change (P > 0.05) in baseline estradiol throughout the study period. All levonorgestrel and antide cats returned to estrus after treatment withdrawal. Results demonstrate that: (1) both antide and levonorgestrel are effective for inducing short-term suppression of follicular recruitment and ovulation in the cat; (2) inhibition is reversible; and (3) GnRH antagonists and progestins differentially regulate basal estradiol secretion. This study also confirmed a relatively high incidence of spontaneous ovulation in the cat, a species generally considered to be an induced ovulator.

A prospective study of the forearm bone density of users of etonorgestrel- and levonorgestrel-releasing contraceptive implants

BACKGROUND

The aim of the study was to compare bone mineral density (BMD) before insertion and at 18 months of use of etonorgestrel- and levonorgestrel-releasing contraceptive implants.

METHODS

One hundred and eleven women, 19-43 years of age, were randomly allocated to two groups: 56 to etonorgestrel and 55 to levonorgestrel. BMD was evaluated at the midshaft of the ulna and at the distal radius of the non-dominant forearm using dual-energy X-ray absorptiometry before insertion and at 18 months of use.

RESULTS

There was no difference in baseline demographic or anthropometric characteristics, or in BMD of users of either model of implant. BMD was significantly lower at 18 months of use at the midshaft of the ulna in both groups of users. However, no difference was found at the distal radius. Multiple linear regression analysis showed that the variables associated with BMD at 18 months of use in both implant groups were baseline BMD, body mass index (BMI) and difference in BMI (0 versus 18 months of use).

CONCLUSIONS

Women of 19-43 years of age using either one of the implants showed lower BMD at 18 months of use at the midshaft of the ulna, however, without a difference at the distal radius.

Levonorgestrel hormone releasing intrauterine system (Mirena) as a contraceptive in egg donors: case report

We report the safe use of levonorgestrel hormone releasing intra uterine system (Mirena) as a contraceptive in egg donors during a treatment cycle. In the first case report, a 29-year-old egg donor using the Mirena coil for contraception and two egg recipients, aged 41 years and 32 years respectively underwent standard IVF treatment, oocyte retrieval in the egg donor and in vitro fertilization followed by embryo transfer in the recipient. The outcome of IVF cycle using donor eggs was satisfactory with successful pregnancy in the egg recipient. The second case involved a 34-year-old egg donor using the Mirena coil and a 44-year-old recipient. Our findings suggest that egg donors can safely use the (Mirena) as a contraceptive device during treatment, without compromising follicular development and oocyte quality.

Effect of intermittent treatment with mifepristone on bleeding patterns in Norplant® implant users

A double-blind, placebo-controlled, randomized trial, was carried out in 120 Norplant users to evaluate the effect of mifepristone, 100 mg/day administered for 2 consecutive days every 30 days, on the vaginal bleeding pattern. Treatment was given from months 2-7 of implant use. Volunteers recorded bleeding and spotting days, during treatment and for the ensuing 6-month period. During treatment, women on mifepristone recorded the same frequency of bleeding/spotting episodes but significantly less prolonged bleeding episodes than placebo controls (mean +/- SD: 11 +/- 3 vs. 22 +/- 23 days) and their total number of bleeding days was 35% lower than in the placebo group. After the end of mifepristone use, bleeding patterns were similar in both groups. One pregnancy occurred in the mifepristone-treated group, in month 6 of treatment, the outcome was a healthy male baby. We conclude that intermittent administration of mifepristone can offer a clinically significant improvement of the vaginal bleeding pattern in Norplant users.

Postcoital treatment with levonorgestrel does not disrupt postfertilization events in the rat

Levonorgestrel (LNG), a progestin widely used for regular hormonal contraception, is also used for emergency contraception (EC) to prevent pregnancy after unprotected intercourse. However, its mode of action in EC is only partially understood. One unresolved question is whether or not EC prevents pregnancy by interfering with postfertilization events. Here, we report the effects of acute treatment with LNG upon ovulation, fertilization and implantation in the rat. LNG inhibited ovulation totally or partially, depending on the timing of treatment and/or total dose administered, whereas it had no effect on fertilization or implantation when it was administered shortly before or after mating, or before implantation. It is concluded that acute postcoital administration of LNG at doses several-fold higher than those used for EC in women, which are able to inhibit ovulation, had no postfertilization effect that impairs fertility in the rat.

Risk-benefit effects of implantable contraceptives in women

Contraceptive implant technology has been used by millions of women throughout the world. The three marketed implant systems today are levonorgestrel-releasing implants: Norplant and Jadelle, and a single etonogestrel-releasing implant, Implanon. The main benefits common to these delivery systems are their safety, high effectiveness, ease of use, long duration of action (3 - 5 years) and reversibility. Bleeding disturbances are the main adverse events associated with implantable contraceptives. Other minor risks relate to the insertion and removal procedures, which require adequately trained providers as well as aseptic techniques. Furthermore, since initiation and discontinuation of use is provider-dependent and not controlled by the user, there may be a risk of coercion of use on the one hand or, on the other hand, difficulty in access to initiating use, if trained providers are not readily available. Although no single contraceptive method is perfect or appealing to all, contraceptive implants are safe and fulfil a very important need among fertility regulation methods.

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.