Pituitary and ovarian function and clinical performance during the use of a levonorgestrel-releasing intracervical contraceptive device

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.

Systematic Review of Postfertilization Effects and Potential for Embryo Formation and Loss during the Use of Intrauterine Devices

Objectives

This review sought to evaluate the evidence for embryo formation during intrauterine device (IUD) use, to articulate how often embryo loss occurs in well-designed studies, and to comment on other bodies of literature suggestive of postfertilization mechanisms of action of IUDs.

Methods

The MEDLINE, EMBASE, and Ovid databases were searched for English-language studies of markers of pregnancy in IUD users in May 2018. Studies of human chorionic gonadotropin (hCG) were subjected to quality assessment based on the US Preventive Services Task Force quality tool. Bias of studies assessing pregnancy in other ways was assessed on a study-to-study basis.

Results

In all, 1,073 studies were identified and 138 were read in detail. Twenty-three studies of β-hCG, 4 studies of direct observation of embryos in fallopian tubes, 2 studies of pregnancy-specific binding globulin (PSBG), and 1 study of heat-shock protein 10 (Hsp10) or chaperonin 10 were included. In all studies considered together, 7.3 percent of IUD users had evidence of fertilization and pregnancy failure. In good-quality studies, 4.5 percent had evidence of fertilization and pregnancy failure.

Discussion

There are no randomized trials of embryo formation and loss in IUD users compared with noncontracepting controls. Studies of β-hCG span a large spectrum of quality, but several good-quality studies exist, which support embryo formation and loss in IUD users. Evidence of embryos found in tubes is moderate and evidence of PSBG and Hsp10 elaboration was limited, but these are also concerning for embryo formation and loss.

Conclusion

There is good-quality evidence of embryo formation and loss in IUD users. Studies are inconsistent, and the stated conclusions of several papers inaccurately diminish postfertilization evidence of embryo formation. To better assess the rate of embryo loss in IUD users compared with non-users, future research should include well-designed prospective trials and less subjective assessments of embryos in fallopian tubes.

Summary

A systematic review was carried out examining the English-language literature in the MEDLINE, EMBASE, and Ovid databases for evidence of embryo formation and loss during IUD use. In all, 1,073 studies were identified and 138 were read. There are no randomized trials and evidence ranges in quality, but evidence for the embryo formation and loss in 4.5 percent of IUD users exists in good-quality research. Further research is needed to compare embryo loss in IUD users to loss in controls.

Mechanisms of action of intrauterine devices: update and estimation of postfertilization effects

There are many potential mechanisms of action for the intrauterine device (IUD), which vary by type of IUD (inert, copper, or hormonal). This paper reviews the evidence for each potential mechanism of action. On the basis of available data for fertilization rates and clinical pregnancy rates, the relative contribution of mechanisms acting before or after fertilization were quantitatively estimated. These estimates indicate that, although prefertilization effects are more prominent for the copper IUD, both prefertilization and postfertilization mechanisms of action contribute significantly to the effectiveness of all types of intrauterine devices.

A 12-month comparative clinical investigation of a levonorgestrel-releasing intracervical device situated in the uterine cavity or cervical canal

A randomized study was performed in two clinics in order to compare the efficacy, safety and acceptability of a new model of a levonorgestrel-releasing intracervical device situated either in the cervical canal (group I) or in the uterine cavity (group II). Group I included 151 women (age 18-43) and group II, 147 women (age 19-43). The number of nulliparous women was 145. The total expulsion rate was 9.1%. The expulsion rate was lower among nulliparous women (4.8%) than among parous women (13.1%). There was also a significant difference in the expulsion rates between the two clinics. Two pregnancies occurred in both groups and two of these were ectopic, one in each group. The other two occurred after unnoticed expulsion. These figures give 12-month cumulative pregnancy rates of 1.3% and 1.4% in groups I and II, respectively. Total infection rate was 0.3%. The continuation rates were 82.1% in group I and 85.0% in group II after the first year. At three-month follow-up there were significantly fewer menstrual problems in group I than in group II (p = 0.0266). It is concluded that expulsion is still a problem with a small device but it may be diminished by intrauterine insertion and by selecting the users carefully.

Ovarian function after seven years' use of a levonorgestrel IUD

Fifteen women with regular menstrual periods and seven amenorrheic women who had been using a levonorgestrel-releasing (LNg) IUD for more than seven years were studied. For controls, eight women using TCu380Ag IUDs for more than seven years were studied during two complete menstrual cycles. Ovarian function was assessed with hormonal determination and ultrasound examinations. The regularly menstruating women were studied for two complete menstrual cycles and the amenorrheic women for eight weeks. In the regularly menstruating LNg-IUD users, according to progesterone levels, 93% of the cycles were ovulatory but just 58% of these 'ovulatory' cycles showed normal follicular growth and rupture. Follicular cysts and luteinization of regressing follicles were observed in 42% of the 26 'ovulatory' cycles studied. SHBG capacity was decreased in the LNg-IUD users compared with the TCu380Ag users. Progesterone levels were lower in the LNg-IUD users compared with the TCu380Ag users but this difference was not statistically significant. Preovulatory estradiol and LH levels were lower in the LNg-IUD users than in the TCu380Ag users. These differences were not statistically significant. For the amenorrheic women, five had follicular cysts that disappeared spontaneously within 45 days. Two women showed follicular development and rupture. The presence of good cervical mucus was observed in 69% of the ovulatory cycles studied in the LNg-IUD users. This indicates that effects on cervical mucus cannot be the main mechanism of action of the LNg-IUDs. It is concluded that LNg-IUDs may exert a contraceptive effect in many different ways, such as inhibition of ovulation, endometrial changes preventing implantation, alteration of physical and chemical properties of cervical mucus affecting sperm transport and subtle disturbances in hypothalamic pituitary ovarian function, resulting in alterations of follicular development and rupture.

Effects on the endometrium, endo- and exocervix following the use of local progestogen-releasing delivery systems

Some conflicting reports have appeared in the literature as to the effect of progestogens on the endometrium and on the endo- and exocervix in animals and humans. Hyperplasia of the endometrial and endocervical epithelium has been reported in some non-human primates following the administration of progestogens. In other studies no evidence has been found for such changes. In women using combined oral contraceptives, it has been claimed that the progestogen component causes adenomatous hyperplasia of the endocervix and that this hyperplastic transformation could be a precursor to adenocarcinoma of the cervix. So far, there is, however, no evidence in the literature to confirm this hypothesis. In view of the development of new delivery systems with a constant release of small amounts of progestogens, previous reports in the literature on hyperplasia and potential malignant transformation of the endometrium and the endocervix have been a matter of concern. The aim of the present study is therefore to review results from studies in animals and humans in particular with reference to the effect of a local release of various progestogens on the endometrium and the endo- and exocervix.

Plasma levonorgestrel levels and ovarian function during the use of a levonorgestrel-releasing intracervical contraceptive device

Levonorgestrel, estradiol and progesterone plasma concentrations were measured over four years of use of a 20 micrograms/day levonorgestrel-releasing intracervical device (LNG-ICD). The mean levonorgestrel concentration showed a slight decline, being 142 + 46 (SD) pg/ml in the third month and 81 +/- 22 pg/ml in the 48th month of LNG-ICD use. However, considerable interindividual variation in levonorgestrel plasma levels between study subjects was observed. In 77% of the monitored cycles, ovulation or a luteinized follicle was observed when judged by a plasma progesterone elevation of over 5 ng/ml. Some follicular function was also noted in anovulatory cycles. Inhibition of ovulatory ovarian function is not the mode of contraceptive action of the LNG-ICD.

Clinical performance of a levonorgestrel-releasing intracervical contraceptive device during the first two years of use

One-hundred-and-ninety-eight women used a levonorgestrel-releasing intracervical contraceptive device (LNG-ICD) designed to release 20 micrograms levonorgestrel/day. Clinical performance during the first two years of LNG-ICD use was evaluated. A total of seven pregnancies occurred during the study period, all of them during the first year. Six pregnancies were after unnoticed expulsion of the device. One pregnancy occurred in an epileptic women using carbamazepine, with the LNG-ICD remaining in situ. Eighteen spontaneous expulsions occurred, 16 during the first year and 2 during the second year. Three pelvic infections were observed, all of them during the first year. Bleeding problems, hormonal side effects and other medical reasons were the most common side effects resulting in removal of the device. The continuation rate was 72.6 per cent after one year and 57.1 per cent after two years.

Patterns of bleeding and body iron stores during the use of a levonorgestrel-releasing intracervical device

A levonorgestrel-releasing intracervical device (LNG-ICD) was inserted in 198 women. The subjects registered bleeding and spotting days on special cards, which were analyzed after one year of treatment. Bleeding and spotting days gradually declined from sixteen during the first month to seven during the seventh month, and they remained under that level until the end of the first year. There were more days of spotting than bleeding. Eleven per cent of the subjects experienced at least 90 days non-bleeding interval during the first year of LNG-ICD use. There were no significant changes in blood hemoglobin concentrations during the first four years of LNG-ICD use. The mean serum ferritin concentration increased from 38 micrograms/l at the beginning to 97 micrograms/l at the end of the fourth year.

Clinical performance of a levonorgestrel-releasing intracervical contraceptive device during the first year of use

One-hundred-and-ninety-eight women used a new type of levonorgestrel-releasing intracervical contraceptive device (LNG-ICD) designed to release 20 micrograms levonorgestrel/day. The insertion took place within 7 days of menstruation. Clinical performance during the first year of LNG-ICD use was evaluated. Seven pregnancies occurred during the study period; one in an epileptic woman using carbamazepine, 300 mg/day, and the other six in healthy women after unnoticed expulsion of the ICD. Sixteen spontaneous expulsions occurred. The most common reasons for removal were side effects, including bleeding disturbances, hormonal side effects and other medical reasons. The continuation rate was 72.6 per cent after one year. Three pelvic infections were observed.

Five years' experience with levonorgestrel-releasing IUDs

Two levonorgestrel-releasing IUDs and a copper-releasing IUD of the same shape were studied in a randomized comparative study over five years. The levonorgestrel-releasing IUDs released 20 micrograms or 30 micrograms per day. The Pearl index during the 10,600 woman-months of LNG-IUD use was 0.11. The control device releasing copper had a Pearl index of 1.6. The amount and duration of menstrual bleeding was greatly reduced, leading to a high incidence of oligo- or amenorrhea. The continuation rate in this pioneer trial was 53 per 100 users for the levonorgestrel-releasing IUD (LNG-IUDs) and 50 per 100 users for the copper-releasing IUD (Nova T). The removal rates for reasons other than amenorrhea were not significantly different. Discontinuation because of amenorrhea occurred during the first two years, the cumulative termination rate for this reason was 11.6 per 100 users at five years. The LNG-IUDs removed for investigation after five years of use revealed that the devices contained about 40 percent of the original load. The effective lifespan of the device has been demonstrated by this study to be five years; the residual steroid gives an additional safety period of two more years. The LNG-IUD is a highly effective reversible contraceptive method, which strongly reduced the amount and duration of bleeding. During the first two months there is scanty but frequent spotting which, like the high incidence of oligo- and/or amenorrhea, requires counselling of health personnel and women using LNG-IUDs.

Intracervical release of ST-1435 for contraception

Seven women used an ST-1435-releasing intracervical contraceptive device (ST-ICD), inserted immediately after the cessation of menstrual bleeding. Patterns of bleeding and clinical performance were evaluated and plasma concentrations of ST-1435, estradiol, progesterone and gonadotropins were measured by radioimmunoassays. The results of ten months of treatment are presented. There were no uniform patterns of bleeding. No hormonal side-effects were registered. The plasma concentration of ST-1435 reached 100 pg/ml within two hours after insertion of an ST-ICD. No ovulations occurred during the initial three months of treatment. A rapid decline in the plasma concentrations of ST-1435 was observed; during the tenth month the concentration of ST-1435 was under the sensitivity of the radioimmunoassay of ST-1435. Hence, the release of ST-1435 from Silastic was too rapid for long-acting contraceptive purposes.