A randomized, double-blind study of two combined and two progestogen-only oral contraceptives

The efficacy, safety, and tolerability of an estrogen-free oral contraceptive drospirenone 4 mg (24/4-day regimen) in obese users

OBJECTIVES

This study aimed to compare contraceptive efficacy and safety of drospirenone 4 mg in a 24/4-day regimen in nonobese and obese users and describe pharmacokinetics according to bodyweight.

STUDY DESIGN

We analyzed data from three drospirenone 4 mg trials (2 European and 1 United States) to report outcomes in nonobese (body mass index <30 kg/m2) and obese (body mass index ≥30 kg/m2) users. We used data from the US trial to calculate the Pearl Index (pregnancies per 100 woman-years) in nonbreastfeeding participants aged ≤35 years at enrollment for confirmed pregnancies. We assessed safety outcomes from all trials based on reported treatment-emergent adverse events. We evaluated pharmacokinetics by bodyweight in the US trial.

RESULTS

The three trials combined comprised 2152 nonobese and 425 obese participants, including 590 nonobese and 325 obese participants in the US trial. Eight nonobese and four obese participants had confirmed pregnancies in the US trial, resulting in Pearl Indices of 3.0 (95% CI: 1.3-5.8) and 2.9 (95% CI: 0.8-7.3), respectively. Two-hundred forty-four (11.3%) nonobese and 39 (9.2%) obese participants discontinued due to a treatment-emergent adverse event. The pharmacokinetic analysis included 814 participants with a median weight of 73 (interquartile range 61-89) kg and median plasma drospirenone exposure (AUC0-24ss) of 661.3 (interquartile range 522-828) ng∙h/mL. Changing bodyweight from the median to the fifth percentile (51 kg) or 95th percentile (118 kg) changed drospirenone exposure (AUC0-24,ss) by 22.2% and -23.6%, respectively.

CONCLUSIONS

Drospirenone 4 mg demonstrated similar contraceptive efficacy for both nonobese and obese users despite a difference in exposure based on bodyweight.

IMPLICATIONS

Our limited comparison between obese and nonobese users of drospirenone-only oral contraception demonstrated no evidence that efficacy or discontinuation for adverse events differs between groups. Serum drospirenone levels vary by bodyweight and may correlate with bleeding outcomes.

Combined Hormonal Contraception during Breastfeeding-A Survey of Physician's Recommendations

Until breastfeeding is established, progesterone-only pill (POP) use is preferable over combined hormonal contraception (CHC), as the latter potentially reduces milk production. Yet, POPs are often associated with breakthrough bleeding (BTB), and irregular spotting is often a reason for their cessation. Conversely, CHC is less associated with BTB but is not usually prescribed, even if breastfeeding has been established, despite its verified safety profile. Here, we surveyed physicians' perception of CHC safety during breastfeeding through an online questionnaire (N = 112). Physicians were asked if they would prescribe CHC to a woman three months postpartum, breastfeeding fully, and suffering from BTB while using POPs. Half of the physicians responded they would, 28% would not until six months postpartum, while 14% would not during breastfeeding. Of the physicians that would prescribe CHC, 58% would without any reservation, 24% would only after discussing milk reduction with the patient, 9% would use a pill with a lower hormonal dose, and 9% would only prescribe CHC 3 months postpartum. The main risk associated with CHC during breastfeeding, as perceived by physicians, is a potential decrease in breast milk production (88%). While some physicians consider CHC unsafe during breastfeeding, most health organizations consider CHC compatible with breastfeeding 5-6 weeks after birth. Thus, there is a gap in the attitude and knowledge of physicians about the safety profile of CHC, and only half acknowledge that the risk of BTB justifies the use of CHC instead of POPs while breastfeeding three months postpartum. We highlight the importance of physician's education, advocate CHC breastfeeding compatibility if breastfeeding has been established (i.e., 30 days postpartum), and underline the importance of discussing the option of CHC with patients in case POPs have unwanted side effects.

Effectiveness and efficacy rates of progestin-only pills: A comprehensive literature review

OBJECTIVES

To synthesize published literature on POP effectiveness and efficacy.

STUDY DESIGN

We searched PubMed Central, PubMed, and the Cochrane library through March 07, 2022. We included articles written in English reporting a Pearl Index or life table rate for pregnancy. We excluded articles only assessing formulations that: were never marketed globally, are only sold in combination with estrogen, are currently sold only for noncontraceptive purposes, or were not given to participants continuously. Four researchers independently extracted data and two analyzed data using Excel and R.

RESULTS

We included 54 studies. Among studies at low or moderate risk of bias, the median Pearl Index rate (the failure rate during typical use) was 1.63 (range 0.00-14.20, IQR 4.03) and the median method failure Pearl Index rate (the failure rate during perfect use) was 0.97 (range 0.40-6.50, IQR 0.68). Excluding the newer formulations, Desogestrel and Drospirenone, which are closer to combined oral contraceptives in that they prevent pregnancy by inhibiting ovulation, the median Pearl Index rate is 2.00 (range 0.00-14.12, IQR 2.5) and the median method failure Pearl Index rate is 1.05 (range 0.00-10.90, IQR 1.38).

CONCLUSIONS

Among studies at low or moderate risk of bias, the median Pearl Index rate during typical POP use was much lower than currently estimated (7.00), while the median perfect use rate was similar to current estimates.

IMPLICATIONS

Future research should investigate the possibility that POPs may be much more effective during typical use than currently believed.

Progestogen-only pills: which progestogen would be ideal

Compared with nonuse, combined hormonal contraceptives containing estrogen and a progestogen are associated with a roughly 2- to 3-fold increased risk of venous and a 2-fold increased risk of arterial thromboembolism, including stroke and acute myocardial infarction. These events are, however, overall rare among women of reproductive age. Historically, progestin-only pills were not thought to be linked with any thromboembolic risk increase. Therefore, these preparations may be valuable options in women who are ineligible to take combined hormonal contraceptives. Until recently, only progestogens with partial androgenic activities were available. As demonstrated in animal studies, more modern progestogens such as drospirenone with its anti-mineralocorticoid effects may be associated with even more favorable aspects, which have to be clinically demonstrated, however, in future studies.

Comparing cervical mucus changes in response to an oral progestin or oestrogen withdrawal in ovarian-suppressed women: a clinical pilot

Purpose: Prior studies evaluating the effect of administered progestogens on peak cervical mucus have not controlled for the influence of endogenous hormones. To address this, we treated women with a gonadotropin-releasing hormone (GnRH) agonist to suppress the hypothalamus-pituitary-ovarian (HPO) axis and used transdermal oestradiol replacement to stimulate peak cervical mucus and then evaluated the effects of an oral progestin or oestradiol withdrawal. Materials and methods: We used a crossover design to examine cervical mucus changes in women receiving transdermal oestradiol replacement following intramuscular administration of leuprolide acetate. After increasing oestradiol patches to mid-cycle levels, subjects were assigned to either 0.35 mg oral norethindrone with continuation of the patches (NET) or oestradiol withdrawal by patch removal (E2WD). We collected serum and cervical mucus samples at 0, 2, 4, 6, 22 and 24 h following the intervention. Results: We analysed 12 cycles (6 NET, 6 E2WD) from three subjects. Baseline cervical mucus scores were favourable to sperm penetration [NET median 11, interquartile range (9-12), E2WD 13 (12-13)]. Two hours after removal of oestradiol patch or administration of norethindrone, cervical mucus scores declined [NET 8.5 (4-9), E2WD 10.5 (10-12)]. Low cervical mucus scores persisted at 24 h with NET [8.0 (7-8)] but not E2WD [10.5 (8-11)]. Conclusions: We observed a rapid decline in cervical mucus Insler scores following administration of a single dose of oral norethindrone, and scores remained lower and unfavourable through 24 h. Oestradiol withdrawal did not result in similar unfavourable changes.

Over-the-Counter Access to Oral Contraceptives for Adolescents

Oral contraceptives (OCs) are used by millions of women in the U.S. The requirement to obtain OCs by prescription from a clinician may serve as a barrier to contraceptive initiation and continuation for women, in particular adolescents. Over-the-counter (OTC) availability would reduce this barrier and could further reduce unintended pregnancy rates. This review explores the scientific issues and regulatory processes involved in switching OCs to OTC status for minor adolescents. We review: (1) the regulatory criteria for switching a drug to OTC status; (2) risk of pregnancy and safety during use of OCs including combined oral contraceptives and progestin-only pills for adolescents; (3) the ability of adolescents to use OCs consistently and correctly; (4) OTC access to OCs and potential effect on sexual risk behaviors; and (5) the potential for reduced opportunities for clinicians to counsel and provide recommended reproductive health care to adolescents. We find strong scientific rationale for including adolescents in any regulatory change to switch OCs to OTC status. OCs are safe and highly effective among adolescents; contraindications are rarer among adolescents compared to adult women. Ready access to OCs, condoms, and emergency contraception increases their use without increasing sexual risk behaviors.

Progestin-only pills for contraception

BACKGROUND

The introduction of a new progestin-only oral contraceptive in Europe has renewed interest in this class of oral contraceptives. Unlike the more widely used combined oral contraceptives containing an estrogen plus progestin, these pills contain only a progestin (progestogen) and are taken without interruption. How these pills compare to others in their class or to combined oral contraceptives is not clear.

OBJECTIVES

This review examined randomized controlled trials of progestin-only pills for differences in efficacy, acceptability, and continuation rates.

SEARCH METHODS

Through October 2013, we searched the computerized databases MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), POPLINE, and LILACS for studies of progestin-only pills. We also searched for current trials via ClinicalTrials.gov and ICTRP. Previous searches also included EMBASE.

SELECTION CRITERIA

We included all randomized controlled trials in any language that included progestin-only pills for contraception.  We incorporated any comparison with a progestin-only pill; this could include different doses, other progestin-only pills, combined oral contraceptives, or other contraceptives.

DATA COLLECTION AND ANALYSIS

The first author abstracted the data and entered the information into RevMan 5. Another author performed a second, independent data abstraction to verify the initial data entry.We attempted to extract life-table rates (actuarial or continuous) and used the rate difference as the effect measure. Where life-table rates were not published, we used the incidence rate ratio (ratio of Pearl rates). Where only the crude number of events was published, we calculated the Peto odds ratio with 95% confidence interval (CI) using a fixed-effect model. For continuous variables, the mean difference (MD) was computed with 95% CI. Because of disparate exposures, we were not able to combine studies in meta-analysis.

MAIN RESULTS

Six trials met the inclusion criteria. We have not found any new studies since the initial review. In the trial comparing the desogestrel versus levonorgestrel progestin-only pill, desogestrel was not associated with a significantly lower risk of accidental pregnancy; the rate ratio was 0.27 (95% CI 0.06 to 1.19). However, the desogestrel progestin-only pill caused more bleeding problems, although this difference was not statistically significant. The trial comparing low-dose mifepristone versus a levonorgestrel progestin-only pill found similar pregnancy rates. In the trial comparing ethynodiol diacetate versus a combined oral contraceptive, irregular cycles occurred in all women assigned to the progestin-only pill (odds ratio 135.96; 95% CI 7.61 to 2421.02). In a trial comparing two progestin-only and two combined oral contraceptives, the progestin-only pill containing levonorgestrel 30 μg had higher efficacy than did the pill containing norethisterone 350 μg. An early trial found megestrol acetate inferior to other progestin-only pills in terms of efficacy. A study of the timing of pill initiation after birth found no important differences, but high losses to follow up undermined the trial.

AUTHORS' CONCLUSIONS

Evidence is insufficient to compare progestin-only pills to each other or to combined oral contraceptives.

Progestin-only contraceptive pill use among women in the United States

BACKGROUND

Progestin-only contraceptive pills (POPs) offer a safe and effective contraceptive option, particularly for women at increased risk of venous thromboembolism. However, the prevalence of POP use among women in the United States is unknown.

STUDY DESIGN

We analyzed population-based data from 12,279 women aged 15-44 years in the National Survey of Family Growth. Data were collected continuously from 2006 to 2010 by in-person, computerized household interviews. Analyses describe POP use across sociodemographic and reproductive characteristics and thromboembolic risk profiles.

RESULTS

Overall, 0.4% of all reproductive-aged women in the United States currently use POPs. POP use was higher among parous, postpartum and breastfeeding women than their counterparts (all p values<.001). Women at higher risk of thromboembolism (older, obese, diabetic or smoking women) had similar proportions of POP use as women without those risks.

CONCLUSION

POPs are rarely used by US women. While data on chronic disease were limited, our results suggest that relatively few women with increased risk of thromboembolism are considering POPs when choosing an oral contraceptive.

The state of hormonal contraception today: benefits and risks of hormonal contraceptives: progestin-only contraceptives

The progestin component of hormonal contraceptives accounts for most of their contraceptive effects. Several dosage forms of progestin-only contraceptives have been developed, including pills, injectables, implants, and intrauterine devices. Emergency contraceptives may also contain progestin only and are indicated for prevention of pregnancy following unprotected intercourse or contraceptive failure. Each form has benefits, some specific to the form. An understanding of benefits and risks allows clinicians a wider choice when recommending effective hormonal contraception.

Estrogen-free oral hormonal contraception: benefits of the progestin-only pill

Although combined oral contraceptives (COCs) are commonly used and highly effective in preventing pregnancy, they may not be suitable for some women. COC use is associated with increased rates of cardiovascular events and is not recommended in nonbreastfeeding women in the immediate postpartum period or in breastfeeding women during the initial 6 months of breastfeeding. Moreover, estrogen-related adverse effects, such as headache, are common. Estrogen-free progestin-only pills (POPs) are a valuable option in women who prefer to take an oral hormonal contraceptive, but are ineligible for, or choose not to use, COCs. Although some POPs have been associated with lower contraceptive effectiveness than COCs, the POP containing desogestrel has shown similar contraceptive effectiveness to COCs. The most commonly reported complaints in women using all POPs are bleeding problems. Counseling women interested in using POPs about the variable bleeding patterns associated with this method may improve compliance and acceptance.

Progestin-only pills for contraception

BACKGROUND

The introduction of a new progestin-only oral contraceptive in Europe has renewed interest in this class of oral contraceptives. Unlike the more widely used combined oral contraceptives containing an estrogen plus progestin, these pills contain only a progestin (progestogen) and are taken without interruption. How these pills compare to others in their class or to combined oral contraceptives is not clear.

OBJECTIVES

This review examined randomized controlled trials of progestin-only pills for differences in efficacy, acceptability, and continuation rates.

SEARCH STRATEGY

We searched the computerized databases MEDLINE, Cochrane Central Register of Controlled Trials (CENTRAL), POPLINE, LILACS, and EMBASE for studies of progestin-only pills. We also searched for current trials via ClinicalTrials.gov and ICTRP.

SELECTION CRITERIA

We included all randomized controlled trials in any language that included progestin-only pills for contraception. We incorporated any comparison with a progestin-only pill; this could include different doses, other progestin-only pills, combined oral contraceptives, or other contraceptives.

DATA COLLECTION AND ANALYSIS

The first author abstracted the data and entered the information into RevMan 5. Another author performed a second, independent data abstraction to verify the initial data entry. Because of disparate exposures, we were not able to combine studies in meta-analysis.

MAIN RESULTS

Six trials met the inclusion criteria. In the trial comparing the desogestrel versus levonorgestrel progestin-only pill, desogestrel was not associated with a significantly lower risk of accidental pregnancy; the rate ratio was 0.27 (95% CI 0.06 to 1.19). However, the desogestrel progestin-only pill caused more bleeding problems, although this difference was not statistically significant. The trial comparing low-dose mifepristone versus a levonorgestrel progestin-only pill found similar pregnancy rates. In the trial comparing ethynodiol diacetate versus a combined oral contraceptive, irregular cycles occurred in all women assigned to the progestin-only pill (odds ratio 135.96; 95% CI 7.61 to 2421.02). In a trial comparing two progestin-only and two combined oral contraceptives, the progestin-only pill containing levonorgestrel 30 mug had higher efficacy than did the pill containing norethisterone 350 mug. An early trial found megestrol acetate inferior to other progestin-only pills in terms of efficacy. A study of the timing of pill initiation after birth found no important differences, but high losses to follow up undermined the trial.

AUTHORS' CONCLUSIONS

Evidence is insufficient to compare progestin-only pills to each other or to combined oral contraceptives.

An integrated analysis of nonmenstrual adverse events with Implanon

This integrated analysis evaluates nonmenstrual adverse events, blood pressure, and body weight changes during the use of the single-rod etonogestrel-containing contraceptive implant, Implanon; these aspects are compared for Implanon and Norplant, the six-capsule implant containing levonorgestrel. Overall, 47% of Implanon users had drug-related adverse events, whereas in the comparative studies the figure for those using Implanon (61%) was slightly lower than that for Norplant users (69%). In all Implanon studies, 12 of 1716 women (0.7%) were affected by serious adverse events that were considered drug related. In comparative studies three of the 689 Implanon users (0.4%) and one of 689 Norplant users (0.1%) had such experiences. The most frequently reported drug-related adverse events were acne, breast pain, headache and weight gain. The adverse events that most often caused discontinuation of Implanon were weight gain and acne. The development or aggravation of acne was a frequent adverse event (in 18.5% of Implanon and 22.3% of Norplant users in the comparative studies) but individual studies indicated that there were also many subjects whose acne improved during implant use. There were gradual increases in body weight over time but these may be only partly attributable to implant use and partly attributable to normal increases over time.

A new low-dose monophasic combination oral contraceptive (Alesse) with levonorgestrel 100 micrograms and ethinyl estradiol 20 micrograms. North American Levonorgestrel Study Group (NALSG)

The efficacy and safety of a new, low-dose, 21-day combination oral contraceptive containing 100 micrograms of levonorgestrel and 20 micrograms of ethinyl estradiol were evaluated in an open-label, multicenter trial. A total of 1477 subjects were enrolled and had 7870 cycles of exposure as of the data cutoff of this interim report. Of these, 792 subjects had completed six cycles of treatment. A total of five pregnancies occurred during treatment during 7720 efficacy cycles, for a Pearl index of 0.84. To date, 415 (28%) subjects have been withdrawn from the study for any reason, including 131 (9%) due to adverse events. The cumulative life table pregnancy rate was 0.0041 per woman entering the sixth cycle. Breakthrough bleeding alone occurred in 4.3% of the cycles and breakthrough bleeding and spotting occurred together during 11% of the cycles. Of the cycles evaluable, 2.6% were amenorrheic. The most commonly reported adverse events in this trial considered at least possibly drug related were headache (14%) and metrorrhagia (8%). This formulation provides contraceptive efficacy similar to higher-dose oral contraceptives, while maintaining a safety and common OC side effect profile that is consistent with prior years of reported use with levonorgestrel-containing products.

Some methodological considerations of a progestin-only oral contraceptive study from a programmatic perspective

Among the limited number of reports on progestin-oral contraceptives (POCs), noncomparative studies conducted at family planning clinics have been the most often reported. This research trend will probably continue. Generally, noncomparative studies address a number of practical issues on POC use, and such studies have made important contributions to the understanding of this contraceptive modality. However, some studies have presented results that are either difficult to extrapolate for potential users or conflict with other findings. This article reviews several studies and suggests ways to improve the study methodology. Well-conceived, -executed, and -analyzed noncomparative studies can cost-effectively address a number of practical issues of POC use that have not been adequately addressed. Additional topics with programmatic utility, such as the effect of local background variables on POC acceptability, and the place of POCs in the ever-increasing contraceptive spectrum, are also discussed.

A comparative study of two low-dose combined oral contraceptives: results from a multicenter trial

A comparative multicenter clinical trial of two low-dose combined oral contraceptives (OCs) was conducted in Malaysia, Egypt, Thailand, and Mexico. Efficacy, safety and acceptability were investigated in women taking either a norgestrel-based (NG) OC or a norethindrone acetate-based (NA) OC. This paper includes analysis of 892 women, all of whom were at least 42 days but within 26 weeks postpartum and randomly allocated to one of the above OCs. Follow-up visits were scheduled at 1, 4, 8 and 12 months after admission. Baseline sociodemographic characteristics were similar for both groups, as well as compliance. There were nine unintended pregnancies reported; eight of these occurring in the NA group. Adverse experiences were minor with headaches and dizziness being the most common complaints; frequency of reports was similar in both groups. The group taking the NG-based OC had significantly (p < .05) fewer menstrual-related complaints. Discontinuations due to menstrual problems were significantly more common among NA users (primarily amenorrhea). Discontinuations in the NG group were primarily for other personal reasons, e.g. unable to return to the clinic. There was also a significant difference between the two groups for the 11-month gross cumulative life table discontinuation rates due to menstrual problems (p < .01); the NA group had the higher rate.

The safety and efficacy issues of progestin-only oral contraceptives--an epidemiologic perspective

Progestogen-only oral contraceptives (POCs) are generally considered a good contraceptive choice for brestfeeding women and for women who want to use an oral form of contraception, but are not suited for, or cannot tolerate the side effects of, estrogen-containing preparations. However, a number of POCs' safety, efficacy and other related issues remain to be addressed. This paper reviews recent literature and evaluates these issues from an epidemiologic perspective. The small number of users imposes severe limitations in designing epidemiologic studies to address POCs' long-term safety issues, but available information suggests POCs are at least as safe as, if not safer than, COCs. Compared to COCs, POCs are more likely to cause menstrual disturbances which, in turn, could affect their acceptability and lead to poor compliance and hence higher pregnancy rates. POCs' efficacy has been estimated to be between 1.4 and 4.3 pregnancies per 100 woman-years of use. Lower pregnancy rates approaching those of COCs have been reported in centers with good counseling. POCs' benefits outweigh their risks. However, more studies are needed to further address POCs' safety and efficacy issues.

A multicenter clinical trial of a progestin-only oral contraceptive in lactating women

A non-comparative study of a progestin-only oral contraceptive (POC) containing 75 micrograms norgestrel was conducted at 22 sites in 14 countries. This study was designed to evaluate safety, contraceptive efficacy, and the overall acceptability of a POC in breastfeeding women. A total of 4,088 women entered the study over a three-year period and 29,399 woman-months of experience was gathered. Women had follow-up visits at 2, 6, and 11 months after admission. Headaches and vaginal discharge were the medical complaints most commonly reported by women, both prior to and after admission. Menstrual problems were reported by 59% of the women after admission. Of the 3,714 women who returned for at least one follow-up visit, 1,101 (29.6%) discontinued through month 11. The 11-month total discontinuation percentage, including those lost to follow-up (25.3%) was 51.6%. The most common reason given for discontinuation was a woman's desire for a change in contraceptive method. Only 4.9% discontinued pill use for menstrual problems, a percentage far below those generally reported for POCs. Twenty-nine unintended pregnancies occurred through 11 months giving a gross cumulative life table rate of 1.2 per 100 women (Pearl Index = 1.4). The POC appears to be a safe, effective and acceptable contraceptive option for postpartum breastfeeding women.

The progestin-only oral contraceptive--its place in postpartum contraception

The progestin-only oral contraceptive (POC) is not a widely-used method of contraception, possibly due to competition from other contemporary contraceptive methods or misunderstanding and prejudices among clients and/or service providers. Because of its underuse, the POC, as a contraceptive method, is under-studied. This article evaluates the general merits of the POC and its disadvantages relative to combined oral contraceptives (COCs) and other contraceptive methods, specifically during the postpartum period and particularly for breastfeeding women. We find that the POC appears to be a safe and acceptable contraceptive method for postpartum women who are fully or nearly fully breastfeeding at six months postpartum or when menstruation returns. The POC could be considered for use at any time by non-breastfeeding postpartum women. The need for empirical studies of the POC is also discussed.

Menstrual bleeding patterns in untreated women and with long-acting methods of contraception. Task Force on Long-Acting Systemic Agents for Fertility Regulation

The bleeding patterns recorded by women using one of two new types of long-acting hormonal contraception, a levonorgestrel-releasing vaginal ring or a monthly injectable, have been compared with those in an untreated group and those experienced by women using either a combined oral contraceptive (OC) or depot-medroxyprogesterone acetate (DMPA). The frequency of bleeding was very similar between the combined pill users, the ring users and the untreated women, who all recorded an average of 3.2-3.3 bleeding/spotting episodes every 90 days. Monthly injectable users had slightly fewer episodes. Women using a monthly injectable or a vaginal ring had longer bleeding/spotting episodes (5 days) than combined pill users (4 days). However, the untreated women and DMPA users had the longest episodes, averaging 6 days. The median value of the within-woman mean length of bleeding-free intervals was 20.6 days among ring users, 22.3 days in the untreated group, 23.6 days among women given a combined OC or a monthly injectable, and 27.4 days in the DMPA group. Women using any of the long-acting methods had more variable bleeding patterns than untreated women or combined pill users. Over a year of method use, however, the lengths of the bleeding-free intervals recorded by vaginal ring and monthly injectable users became more predictable. It is concluded that these newer methods do not produce the marked bleeding disturbances seen with DMPA.

Ectopic pregnancy in Zimbabwe

One hundred four consecutive ectopic pregnancies were systematically analysed. During the study period, the incidence rate was 110 per 100,000 14-44 year old females per year. A history of prior pelvic infection was given by 53.8% of the cases and was suggested by surgical findings or by histological analysis among 74.9%. Serological evidence of previous chlamydial infection was much more common when ectopic pregnancy occurred in abnormal tubes than in normal tubes or compared to intrauterine pregnancies. The influence of schistosomiasis, endometriosis and ovarian cyst was limited to a very few cases. The analysis of contraceptive habits shows a much higher number of extrauterine pregnancies when the woman is using progestin-only pill than when she is on combined oral tablets.

The efficacy and acceptability of a low-dose levonorgestrel intravaginal ring for contraception in a UK cohort

The efficacy and acceptability of a levonorgestrel-releasing intravaginal ring (IVR) for contraception was assessed in a British cohort studied as part of a multicentre, multinational clinical trial performed under the auspices of the World Health Organisation. One-hundred-and-fifty women took part in the study in two UK centres and completed 1417.5 months of method use. Fifty-nine women discontinued use of the IVR before the end of one year giving an overall discontinuation rate of 39.9 per 100 woman-years. The discontinuation for pregnancy with the ring in situ, was 3.0 per 100 woman-years (life table analysis). Menstrual disturbance, vaginal problems and involuntary expulsion resulted in discontinuation rates of 8.9, 8.4 and 1.6 per 100 woman-years, respectively. This method is an acceptable and effective method of contraception for women.

Clinical experience with the progestogen-only pill

Experience with the progestogen-only pill (POP) in a family planning clinic is presented. From the clinic records, 408 women were identified who had opted to use a POP. Of these, 50 women had used the POP during lactation and these were excluded from the analysis. The remaining 358 women used the POP for up to 150 months, giving a total of 18,125 women-months of use. Three pregnancies occurred, giving a Pearl Index of 0.2 per 100 women-years. Non-menstrual side effects were minor and were reported by 77 women. For the women who discontinued the POP, the main reason was menstrual irregularity (47.5%). However, despite the long-term use by most of the women, almost 40% maintained a mostly regular menstrual pattern. Our findings suggest that the POP provides a very acceptable method of oral contraception for many women and that it should be more actively promoted.

Microdose intravaginal levonorgestrel contraception: a multicentre clinical trial. I. Contraceptive efficacy and side effects. World Health Organization. Task Force on Long-Acting Systemic Agents for Fertility Regulation

A multicentre clinical trial, including 19 centres in 13 countries, assessed the contraceptive efficacy and clinical acceptability of a Silastic 382 vaginal ring releasing 20 micrograms of levonorgestrel for at least 90 days. A total of 1005 women entered the study and 8176.74 woman-months of experience was gathered. The rate of intrauterine pregnancy at one year of use was 3.6 per 100 women (95% confidence interval 2.2-5.0), and of ectopic pregnancy, 0.2% (one case). The principal reasons for discontinuation were menstrual disturbances (17.2% at one year), vaginal symptoms (6.0%) and repeated expulsion of the ring (7.1%). The pregnancy rate with this 20 micrograms levonorgestrel-releasing vaginal ring compares favourably with that of a low estrogen combination oral contraceptive tested by WHO and is less than half that of a progestogen-only oral contraceptive in a WHO randomized study. It is concluded that the WHO intravaginal ring releasing an average of 20 micrograms of levonorgestrel per 24 hours is an effective method of contraception for at least one year of use.

Mini-pill in lactating women

A non-comparative study of the progestogen-only oral contraceptive, norgestrel 0.075 mg, in breast-feeding women was conducted at the Centro de Investigaciones Regionales, Merida, Yucatan, Mexico. The study was designed to evaluate the overall acceptability and contraceptive efficacy of norgestrel in breast-feeding women. This report includes a survey of 200 women, all of whom were less than 26 weeks postpartum at admission; 113 were interval patients and 87 were postpartum. Follow-up visits were scheduled at 2, 6 and 12 months after admission. Overall, women experienced an increase in intermenstrual bleeding, amenorrhea, vaginal discharge and breast discomfort. The discontinuation rate at 12 months was 32.5 and the corresponding lost to follow-up rate was 22.5; this is a measure of acceptability. The 12-month life-table rate for pregnancy was 3.4 with a standard error of 2.0. Three women discontinued use of the mini-pill due to accidental pregnancy. One pregnancy was attributed to user failure and the woman conceived 9 months after entering into the study; the other two were attributed to method failure, one woman conceived 3 months after admission and the other conceived 6 months after admission.

Effectiveness of IUDs: a review

Large, multicenter, randomized trials of IUDs conducted between 1970 and 1986 encompass more than 50,000 woman-years of experience in the two-year interval following device insertion. Taken singly and collectively, these trials demonstrate that IUD failure rates are strongly affected by the age of participants, notably by the proportion of women under age 25 admitted to the studies. Individual trials and overall comparisons indicate further that: 1. Non-medicated devices such as the Mahua steel ring and Lippes loop D have pregnancy rates above 2 per 100 woman-years. 2. The first approved copper IUDs, the Copper 7 and the TCu 200, do not markedly differ in pregnancy rates from standard plastic devices with rates significantly above 2 per 100 woman-years. 3. Five more recent, widely used copper IUDs have had failure rates significantly below 2 per 100 woman-years in multicenter trials. The point estimate of the failure rate was less than 1 pregnancy per 100 woman-years for three of these IUDs. One copper-bearing device had a failure rate significantly below 1 per 100 woman-years. 4. Devices releasing either 25 mcg/day of progesterone or 2 mcg/day of levonorgestrel have had significantly higher failure rates than the more effective copper-releasing IUDs; however, devices releasing 20 mcg/day of levonorgestrel appear at least as effective as the most effective copper IUDs. Long-term IUD failure rates derived from straight assignment as well as randomized trials indicate 4-year gross cumulative failure rates do not exceed 10 per 100 for any of the standard copper devices or the Lippes loop D. Point estimates of the four-year gross cumulative pregnancy rates have been below 5 per 100 users in studies of the TCu 220C, the Nova T, the TCu 380A, and the MLCu 375.

Five-year experience with Norplant implants in Assiut, Egypt

This report describes the five-year experience of the first 250 acceptors of NORPLANT implants in Assiut, Egypt. The five-year net continuation rate was 58.6 per 100 women. The five-year net cumulative pregnancy rate was 1.6 per 100 women. About three-fourths of those who continued use of this contraceptive through the fifth year reported having regular cycles. There was definite improvement in the bleeding pattern with time. The five-year net termination rate because of bleeding problems was 17.7 per 100 women. After 5 years of NORPLANT use there was a slight, statistically insignificant increase in weight, systolic and diastolic blood pressures. Of those who used contraceptives after the end of the five-year term of NORPLANT, about one-third opted to have reinsertion of the implants for a second term. About 96% of those who used NORPLANT through the fifth year reported that their experience with the contraceptive had been satisfactory.

Pharmacokinetics of levonorgestrel in the rat

Levonorgestrel was administered intravenously as a bolus to adult female rats and blood samples were collected at various time intervals. Serum concentrations of levonorgestrel were measured by radioimmunoassay. Analysis of data for two- and three-compartment open models indicated that in the rat, as in the human and the rabbit, a tri-exponential equation provided a better fit of the data. The half-lives for the alpha, beta and gamma phases were 10.1 min, 42.7 min and 23.1 hours, respectively. These values were closer to those reported for women than were the half-lives reported for the rabbit. The alpha and the beta phases appeared to last for 51 min and 1.3 hours, respectively, and the gamma phase was longer than 45 hours.

Why do inadvertent pregnancies occur in oral contraceptive users? Effectiveness of oral contraceptive regimens and interfering factors

Inadvertent pregnancies in combined pill users are not uncommon, and are usually due to errors of tablet taking. However, many factors may contribute to 'pill failure'. In this review the endocrine pharmacology of pill use and the changes reported with missed pills have been considered in detail. The influences of other factors including drug interactions have been reviewed and a series of recommendations made for reducing the risk of pregnancy in each of these circumstances.