Long-term follow-up of women treated with Norplant implants

Impact of one-rod levonorgestrel implant on the blood chemistry profile

The aim of this study was to investigate the effect of a one-rod levonorgestrel implant on the blood chemistry profile, including random blood glucose (RBG), haemoglobin (Hb), alanine transferase (ALT), aspartate transferase (AST), and the lipid profile, including total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglycerides. This prospective cohort study was conducted at Raden Saleh Clinic, Jakarta, from 2010 to 2012. The implants were inserted subdermally in 30 patients. The subjects were evaluated every 6 month up to 2 years. Bivariate analysis using t-test or Wilcoxon signed rank test was performed for all variables. p < 0.05 was considered a significant value. The Hb, RBG, AST, and lipid profile levels were significantly different before and 6 months after one-rod implant insertion (p < 0.05). However, for 24 months, all of the parameters were still within normal limits and did not differ clinically. One-rod levonorgestrel implant insertion has a minimal effect on all blood chemistry profiles.

Safety, efficacy and patient acceptability of the contraceptive and non-contraceptive uses of the LNG-IUS

Intrauterine devices (IUDs) provide highly effective, long-term, safe, reversible contraception, and are the most widely used reversible contraceptive method worldwide. The levonorgestrel-releasing intrauterine system (LNG-IUS) is a T-shaped IUD with a steroid reservoir containing 52 mg of levonorgestrel that is released at an initial rate of 20 μg daily. It is highly effective, with a typical-use first year pregnancy rate of 0.1% - similar to surgical tubal occlusion. It is approved for 5 years of contraceptive use, and there is evidence that it can be effective for up to 7 years of continuous use. After removal, there is rapid return to fertility, with 1-year life-table pregnancy rates of 89 per 100 for women less than 30 years of age. Most users experience a dramatic reduction in menstrual bleeding, and about 15% to 20% of women become amenorrheic 1 year after insertion. The device's strong local effects on the endometrium benefit women with various benign gynecological conditions such as menorrhagia, dysmenorrhea, leiomyomata, adenomyosis, and endometriosis. There is also evidence to support its role in endometrial protection during postmenopausal estrogen replacement therapy, and in the treatment of endometrial hyperplasia.

Levonorgestrel intrauterine system: bleeding disorders and anticoagulant therapy

Hemostatic disorders in women are frequently associated with long-standing menorrhagia. This leads to significant morbidity and adversely affects quality of life. Management of these women poses a particular challenge; medical treatments may be contraindicated, and surgery carries additional risks. The levonorgestrel intrauterine system (LNG-IUS) has been shown to be highly efficacy in reducing menstrual blood loss in women with normal coagulation. It is also a reliable and reversible contraceptive. Data on the use of this system in women with bleeding disorders or those receiving anticoagulant therapy are limited. Analysis of data from four reported studies suggests that LNG-IUS is a viable and safe option for the management of menorrhagia in these women. Whether the underlying hemostatic disorders lead to a shorter duration of action or prolonged irregular bleeding/spotting post insertion is unknown and requires large prospective studies. Proper counselling remains crucial for patients' satisfaction.

A cross-sectional study of the forearm bone density of long-term users of levonorgestrel-releasing intrauterine system

BACKGROUND

There are concerns about the effect of hormonal contraceptives on bone mineral density (BMD), but there is currently no information available on the effect of the levonorgestrel-releasing intrauterine system (LNG-IUS) on BMD. The objective of this study was to compare the BMD of LNG-IUS users with that of controls using the TCu380A intrauterine device (IUD).

MATERIALS AND METHODS

A cross-sectional study paired 53 women, aged 25-51 years, who had been using the LNG-IUS for 7 years, with 53 IUD users, according to age (+/-1 year) and body mass index (BMI; kg/m2) (+/-1). BMD was evaluated at the midshaft of the ulna and the distal radius of the nondominant forearm using double X-ray absorptiometry.

RESULTS

Mean age of women was 34 years. BMI was slightly over 25 in both groups. Estradiol was normal. Mean BMD was 0.469 +/- 0.008 and 0.467 +/- 0.009 and 0.409 +/- 0.009 and 0.411 +/- 0.009 at the midshaft of the ulna and distal radius in LNG-IUS and IUD users, respectively, without significant differences.

CONCLUSIONS

Women aged 25-51 years, using the LNG-IUS for 7 years, had a mean BMD similar to that of the control group of TCu380A IUD users.

A comparative study of the levonorgestrel-releasing intrauterine system Mirena versus the Copper T380A intrauterine device during lactation: breast-feeding performance, infant growth and infant development

BACKGROUND

Mirena is a levonorgestrel-releasing intrauterine system (LNG-IUS) that provides highly effective and long-acting progestogen-only contraception.

OBJECTIVE

The objective of this study was to analyze the possible effects of using LNG-20 microg IUS on breast-feeding performance, infant growth and infant development during the first postpartum year as compared with the Copper T380A intrauterine device (Cu T380A IUD).

DESIGN

This study is a prospective, controlled and randomized trial.

SETTING

The study was conducted at the Department of Obstetrics and Gynecology, Assiut University Hospital, Egypt.

METHODS

Three hundred twenty lactating women asking for initiation of contraception during the early postpartum stage were assigned randomly into two groups, the LNG-20 microg IUS group (n=163) and the Cu T380A group (n=157). The insertions were done 6-8 weeks postpartum. Each participant was followed up at three monthly intervals after insertion and until the first birthday of her baby. During these visits, the breast-feeding pattern was assessed, certain infant physical growth parameters were measured and a set of infant development tests was performed.

RESULTS

No pregnancy occurred in both groups. There were no significant differences in the net continuation rates between the two groups (89.3 for LNG-IUS vs. 90.9 for Cu T380A). The LNG-20 microg IUS group had comparable rates of breast-feeding continuation, complete weaning, full breast-feeding and partial breast-feeding, with the Cu-IUD group. No statistically significant differences were found between groups with regard to all infant physical growth parameters and various infant development tests.

CONCLUSION

The findings of the current study confirm that the use of LNG-20 microg IUS during the first postpartum year in lactating women provides highly effective and acceptable contraception and does not negatively influence breast-feeding or the growth and development of breast-fed infants.

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.

Progestin implants for female contraception

Four different implants, in the form of capsules or covered rods, that release one of the synthetic progestins levonorgestrel, etonogestrel, Nestorone, or Elcometrine and nomegestrol acetate were reviewed. Biocompatible polymers or copolymers of polydimethyl/polymethylvinyl-siloxanes or ethylvinylacetate are used to hold the steroid crystals and to control the rate of release. Once inserted under the skin, these implants release the corresponding steroid continuously over prolonged periods, a process that can be readily interrupted by implant removal. During long-term use of the implant, the released steroid circulates in blood at a fairly stable level. The physical characteristics of the implants, including drug contents and rate of release, serum levels of the progestin during use, and the duration of their effective life are described. Total steroid loads vary in the range of 50 mg to 216 mg; average release rates are in the range of 30-100 ug/day, and effective lives from 6 months to 7 years.

Endometrial expression of glycodelin in women with levonorgestrel-releasing subdermal implants

OBJECTIVE

To determine whether subdermal levonorgestrel implants induce endometrial expression of glycodelin.

DESIGN

Cross-sectional, blinded study.

SETTING

University clinic.

PATIENT(S)

One hundred and eight women with subdermal implants and 19 postmenopausal women.

INTERVENTION(S)

Endometrial biopsies, curettages, and hysterectomies.

MAIN OUTCOME MEASURE(S)

Endometrial glycodelin expression was examined through immunohistochemistry, in situ hybridization, and morphologic endometrial dating.

RESULT(S)

Overall, 80% of the endometrial specimens obtained from women with subdermal levonorgestrel implants stained positive for glycodelin. Endometrial morphology of these women showed proliferative (71%), inactive/weakly proliferative (19%), menstrual or regenerating (6.5%), and other patterns (2.8%). Of these, 79%, 71%, 100%, and 100% were glycodelin positive, respectively. Nineteen specimens were obtained during the midcycle when glycodelin is not normally expressed: of these, 89% stained positive for glycodelin. Implant-related amenorrhea was associated with endometrial glycodelin expression in 58% of the women, whereas the endometrium specimens obtained from women with postmenopausal hypoestrogenic amenorrhea contained no detectable glycodelin.

CONCLUSION(S)

Subdermal levonorgestrel implant use is often associated with endometrial expression of glycodelin. Because glycodelin has been shown to inhibit sperm-egg binding, the induction of glycodelin may contribute to the contraceptive activity of the implant.

Post-marketing surveillance of Norplant® contraceptive implants: I. Contraceptive efficacy and reproductive health☆

The subject of this study to examine the safety and contraceptive efficacy of Norplant, we undertook a 5-year study of follow-up of women initiating use of Norplant, intrauterine device (IUD) or sterilization in eight developing countries. Women attending family clinics were enrolled if they consented and were medically eligible to use Norplant, IUD, or female sterilization. Women who chose to initiate use of IUDs or surgical sterilization served as controls and were frequency matched in 5-year age-bands with women who chose to use Norplant. At admission women had a physical examination, and their medical histories, demographic, and socio-economic characteristics were recorded. Follow-up visits were scheduled in the first 6 weeks after admission and semi-annually thereafter for 5 years irrespective of change of contraceptive method. Incidence rate ratios of health events were estimated for initial and current contraceptive method use. This paper reports reproductive health events and contraceptive efficacy. Altogether, 7,977 women initiating use of Norplant, 6,625 of IUD, and 1,419 of surgical sterilization were admitted. Their mean ages at initiation were 28.5, 28.5, and 29.6 years, respectively. More than 99% were married or cohabiting, and parous. Five-year follow-up was completed by 94.6% of the women. By the end of 5 years, the mean duration of first segment use per initiator was 4.16 years for Norplant, 4.10 years for IUDs, and 4.96 years for sterilization accounting for 39,337 woman-years for Norplant, 31,915 for IUDs, and 7,071 for sterilization. The study accumulated 78,323 woman-years of observation. Pearl pregnancy rates for Norplant, copper IUDs and female sterilization were 0.27, 0.88, and 0.17 per 100 woman-years, respectively. Users of Norplant, copper IUDs, and sterilization had rates of ectopic pregnancy of 0.30, 0.68, and 0.13 per 1,000 woman-years, respectively. Major health events related to the reproductive system were rare. Rates of acute PID were significantly lower among Norplant users than IUD users (p = 0.004). The rate of ovarian enlargement was significantly higher in Norplant users than controls (p <0.001), but not rates of hospitalization for this condition. Vaginitis and vaginal discharge, and low abdominal pain were significantly less frequent in Norplant users than in the other groups. Bleeding disturbances were more frequent among Norplant users than controls but not anemia. The study confirms the high contraceptive efficacy of Norplant, copper IUDs, and female sterilization. The incidence rates of major reproductive health problems were low. There was no significant excess of serious reproductive morbidity among users of Norplant compared to users of IUDs and sterilization.

Empirically based conversion factors for calculating couple-years of protection

Couple-years of protection (CYP) is one of several commonly used indicators to assess international family planning efforts. It has been the subject of much debate, relating in part to the specific conversion factors used to translate the quantity of the respective contraceptive methods distributed to a single measure of protection. This article outlines a comprehensive effort to revisit those conversion factors based on the best available empirical evidence. In most instances, the analysis supports previously established standard conversion factors. However, there are two notable departures. Fewer condoms and spermicides are recommended for each CYP (120 vs. 150), primarily because coital frequency among condom users is lower than previously assumed. Furthermore, for sterilization, the authors recommend the use of country or region-specific conversion factors. Every program evaluation indicator has strengths and weaknesses, and the best program evaluation efforts use a variety of indicators. If CYP is used to evaluate programs, however, the authors believe that the conversion factors presented reflect the best available evidence.

An enzyme immunoassay for serum and urinary levonorgestrel in human and non-human primates

A microtiter plate enzyme immunoassay (EIA) is reported for the measurement of levonorgestrel (LNG) in serum and urine samples of human and non-human primates, and the results are compared to data obtained by radioimmunoassay (RIA). Rabbit polyclonal antibodies were raised against the bovine serum albumin conjugate of the 3-O-carboxymethyl oxime (CMO) derivative of LNG. The enzyme label was produced by the conjugation of horseradish peroxidase to LNG at the 3-position by the same CMO bridge used for the immunogen. The assay requires 2.5 hours to perform using 2.2-azino-di-(3-ethylbenzthiazoline sulfonic acid) diammonium salt as the chromogenic substrate. Serum (100 microliters) is extracted with petroleum ether prior to assay, whereas urine samples (25 microliters) are diluted and measured directly. The sensitivity of the assay is 0.25 pg/well with a 50% displacement of label at 7.5-9.5 pg and a linear response through 250 pg/well. Minimum levels of 8.7 and 10.0 pg/ml can be detected in serum and urine samples, respectively. Changes in serum LNG concentrations were measured in women and non-human primates following LNG implantation or injection. In the non-human primate study, serum LNG concentrations began to rise rapidly following i.m. injection of LNG, with peak levels occurring on days 3 to 5, then decreasing to approximately 25-35% of peak levels for the duration of the study. Circulating concentrations of 1.86 +/- 0.18 ng/ml LNG were reached in women the first week post-insertion of Norplant implants and decreased by 50% at 7-10 days, 75% after 14-21 days, followed by a steady decrease during the next 60-70 days to constant low levels that exhibited a high individual variation. Correlation coefficients of EIA and RIA results were 0.988 for human serum, 0.926 for human urine, and 0.972 for non-human primate serum.

Contraception in diabetic women

Contraceptive prescription in diabetic women with current diabetic mellitus (type I or type II) or in prediabetic women with previous gestational diabetes mellitus must consider the specific metabolic effects and risks in diabetic women. This article addresses these issues, enabling the practitioner to develop individually tailored contraceptive programs to meet the changing needs and demands of the reproductive-aged diabetic woman. If focuses on the most efficacious, reversible option available--hormonal methods and intrauterine devices--both of which have been controversial for diabetic women.

Norplant subdermal contraceptive system: experience in Taiwan

From November 1988 to December 1994, a total of 567 female volunteers were enrolled in Norplant implant studies at the National Taiwan University Hospital. After a median follow-up of 29 months, only 3 of the 529 available cases became pregnant (a cumulative rate of 1.2 pregnancies per 100 users over 5 years). Chromosome analysis of 2 of the 3 abortuses revealed 46,XX/46,XX,inv(3) and 46,XX. Menstrual problems were the most common adverse effects and were also the main reason for discontinuation (65%, 108/166). The continuation rate was 90%, 78%, 70%, 61%, and 42% at the end of 1, 2, 3, 4, and 5 years after insertion, respectively. In the 21 patients who wished to become pregnant, fertility recurred soon after removal of the Norplant implants. The data suggested that the Norplant implants system is a highly effective, safe, and long-acting method of reversible contraception. It would be worthwhile to introduce this contraceptive system to Taiwan's family planning program.

Subdermal contraceptive implants

Subdermal contraceptive implants involve the delivery of a steroid progestin from polymer capsules or rods placed under the skin. The hormone diffuses out slowly at a stable rate, providing contraceptive effectiveness for 1-5 years. The period of protection depends upon the specific progestin and the type of polymer. Advantages of progestin implants include long term contraceptive action without requiring the user's or provider's attention, low dose of highly effective contraception without the use of estrogen, and fertility is readily reversible after the removal of implants. The levonorgestrel implant Norplant R system is the only one that has been approved for distribution. The contraceptive efficacy of Norplant is the highest observed amongst the most effective methods with an annual pregnancy rate of 0.2 during the first and second year and 1.1 on the fifth year. Menstrual problems are the main reason for the discontinuation of Norplant and 9% of women stopped using it during the first year of treatment. Other implants are still under development trying to simplify the method by reducing the number of units and to introduce other progestins that may minimize side effects. Norplant-2 was designed to release the same dose of progestin from only two covered rods. Evaluation of 1400 women enrolled, indicates that over 2 years the cumulative pregnancy rate is below 0.5 per 100 women. There are three single implants under development: Nestorone, 3-Keto-desogestrel and Uniplant that are expected to be effective for 1-2 years. Phase II clinical trials with Nestorone have been completed and no pregnancies have been observed in 1570 woman-months of use. Bleeding irregularities occurred in 20-30% of the women but there were only four terminations because of bleeding problems. A multricentric study is ongoing with a newly designed 3-keto-desogestrel implant named Implanon, which releases approx. 60 micrograms/day of the hormone. The objectives of this study are to assess contraceptive efficacy, safety and acceptability of Implanon. Another multricentric study is ongoing with Uniplant, which releases nomegestrol acetate with a duration of action for only 1 year. The objectives of the trial are to study the endocrine profile of Uniplant users and to evaluate the efficacy and acceptability of the method.

A cohort study of Norplant implant: side-effects and acceptance

OBJECTIVES

Menstrual irregularity is the main cause of termination of Norplant use; a study of its safety and level of acceptance is needed.

STUDY METHODS

A cohort study using medical records of Dr Kariadi Hospital, Semarang, Indonesia and interviews between Norplant and IUD users who had in 1993 been followed-up for 5 years. Expulsion rate, removal rate, level of acceptance and satisfaction were examined.

RESULTS

From 170 Norplant and 168 IUD acceptors, the net cumulative pregnancy rates by month 36 of the Norplant and the IUD groups were 0.0% and 1.19%, respectively (p > 0.05). The net cumulative expulsion rates were 0.61% and 1.32% (p > 0.05). The net cumulative rates of removal for medical reasons were 2.37% and 1.97% (p > 0.05). The net cumulative removal rates for non-medical reasons were 1.80% and 10.38% (p < 0.001); the net cumulative continuation rates were 95.29% and 85.60% (p < 0.002). The net cumulative acceptance rates were 97.04% and 93.83% (p > 0.05). The Norplant users experienced less menstrual and inter-menstrual bleeding and more amenorrhea than the IUD group. The psychological satisfaction scores among the Norplant and IUD users were high (p > 0.05). The Norplant contraceptive is well accepted.

CONCLUSIONS

The findings could be very useful for further steps in promoting Norplant as a contraceptive that is long-acting, with good efficacy, acceptance, and safety.

A preliminary report of Norplant implant insertions in a large urban family planning program

During the 21-month period between August 1, 1991, and April 30, 1993, 2,358 women received Norplant system insertions in either Parkland Memorial Hospital or the Dallas Maternal Health and Family Planning clinics. Forty-three percent of these women were teenagers with 14% 16 years of age or less. Overall, 431 patients received Norplant implants insertions postpartum prior to discharge from the hospital. To date, 138 Norplant systems have been removed, with the proportion of contraceptive implant removals among teenagers being essentially the same as that in more mature women. Of the reasons given by women discontinuing the Norplant system, an unanticipated high incidence of pain in the arm containing the implants, hair loss, and mood changes were noted. We have found the Norplant system to be a highly effective and highly acceptable contraceptive method for a large number of indigent women.

NORPLANT: levonorgestrel-releasing contraceptive implant

NORPLANT is the newest contraceptive system to be introduced world-wide, with nearly a million current users. It consists of six Silastic capsules containing levonorgestrel (LNg), which are inserted under the skin in the arm. Release of the steroid commences immediately so that, after several weeks, circulating levels of LNg stabilize between 0.3 and 0.4 ng/ml of plasma, and they persist elevated with a minor decline for over 5 years. The gross cumulative pregnancy rate at 5 years is 2.6 per 100 woman-years. In the majority of women it produces no abnormalities in a variety of clinical chemistry, metabolic, haematological and coagulation parameters. The most common side-effect is disruption of the menstrual bleeding pattern; this is reported by two-thirds of the users in the first months and by one-third by the fifth year. Because it is the most disturbing side-effect for many users, counselling prior to insertion is of paramount importance. NORPLANT exerts varying degrees of gonadotrophin and ovarian inhibition, including anovulation and luteal insufficiency. Endometrial development is irregular and, irrespective of oestrogen levels, cervical mucus is thick and scanty at all times due to the strong antioestrogenic effect of LNg. Inhibition of sperm penetration fully accounts for the antifertility effect of NORPLANT in ovulatory cycles. The high contraceptive efficacy, lack of serious side-effects, reversibility and the convenience of long-term unattended use explain the high acceptability of NORPLANT.

Changes in serum levels of SHBG, endogenous ligands and levonorgestrel induced by ethinylestradiol in Norplant users

This work was done in search for a model to examine target organ response to fluctuations in serum levels of sex hormone-binding globulin (SHBG) and its ligands. The time course and magnitude of fluctuations of SHBG, levonorgestrel (L-Ng), estradiol (E2), testosterone (T) and dihydrotestosterone (DHT) in serum were examined during and after treatment with 50 ug of ethinylestradiol (EE2) daily for 10 days in 10 volunteer women using NORPLANT implants. Six of these volunteers were also treated with 20 ug of EE2 daily for 7 days and two additional volunteers using a copper-T IUD were treated with 50 ug of EE2 daily for 7 days. In all cases, SHBG and L-Ng levels increased in a close parallel manner several-fold above basal levels during treatment, reaching a maximum around two days after the last EE2 pill. In contrast, the levels of E2 and T increased in one subject, decreased in 5 and remained unchanged in 4, while changes of DHT were unrelated to those of the other ligands. Since the L-Ng "secretion rate" by NORPLANT implants is constant, it follows that the effect of EE2 on its levels is due to a decreased metabolic clearance rate, most likely secondary to the increased binding of L-Ng to SHBG in serum. This interpretation is in agreement with the close parallelism in the fluctuations of L-Ng and SHBG. It is concluded that in NORPLANT users, SHBG and L-Ng, but not the endogenous ligands, behave in a predictable manner in response to EE2. Thus, this model affords the possibility of exploring the influence of SHBG on tissue response to progestins.

Hormonal changes associated with bleeding during low dose progestogen contraception delivered by Norplant subdermal implants

The main side effect associated with the use of Norplant contraceptive implants is a disruption of the menstrual bleeding pattern. To explore the relationship between bleeding and hormonal changes, we analyzed the estradiol (E2) and progesterone (P) patterns that preceded bleeding episodes or that corresponded to periods of amenorrhea in 103 cycles observed among 82 women using Norplant subdermal implants. Five different bleeding patterns were defined: 'normal' (24-45 day cycles), oligomenorrhea (46-90 day cycles), amenorrhea (over 90 day cycles), irregular/frequent bleeding (less than 25 day cycles), and prolonged bleeding (continuous bleeding/spotting for more than 10 days). All 'normal' cycles were associated with a rise followed by a fall in E2 levels preceding bleeding. In half of the 'normal' cycles (28/54), a rise and fall of P was also observed. The same pattern was found in oligomenorrheic cycles, but only two of 12 cycles had a rise and fall of both E2 and P. None of the subjects with amenorrhea had luteal activity. Six of the nine amenorrheic cycles displayed persistently low E2 levels (below 75 pg/ml). The remaining three had a moderate elevation in E2 levels during the sampling period. Sixty percent of the subjects who showed irregular/frequent bleeding (15/25) had low E2 levels (less than 75 pg/ml), without luteal activity, and bleeding occurred without clear evidence of a further drop in E2 levels. In the remaining 40%, bleeding was preceded by a rise and drop of E2 without luteal activity, with the exception of one women, who exhibited a rise and fall of both E2 and P. Samples were obtained in only three subjects during continuous bleeding. One had low E2 levels, and the remaining two bled continuously, in spite of having E2 levels in the normal range. We conclude that ovarian hormones continue to influence endometrial shedding during the use of Norplant contraceptive implants.

Estradiol plasma levels during long-term treatment with Norplant subdermal implants

Estradiol-(E2) plasma levels were assessed in forty-seven women treated for one through seven years with the same set of Norplant implants. Each woman was subjected to one (n = 34), two (n = 11) or three (n = 2) sampling runs. At each sampling run, blood samples were drawn every third or fourth day during 5 or 6 consecutive weeks. Sampling runs were classified as ovulatory (n = 11), anovulatory (n = 49) or uncertain (n = 1) according to progesterone levels. Controls were Copper T users (n = 8), all classified as ovulatory. No significant differences were found for the mean E2 levels between Norplant users and Copper T users and between ovulatory and anovulatory cases. The mean of the peak E2 value found in each sampling run was significantly higher in anovulatory Norplant subjects than in the control group. The mean of the minimum E2 level observed was significantly lower in Norplant cases than in Copper T users. A single woman from the Norplant group and none from the Copper T group had all E2 values below 370 pmol/l. The inhibition of the reproductive function induced by Norplant implants is associated with a wider range of E2 circulating levels. None of the values observed at the extremes should cause serious concerns. High peaks are transitory and opposed by the antiestrogenic effect of levonorgestrel. Persistent low levels which could be associated with a hypoestrogenic state were observed in a single case.