Chinese experience with intrauterine devices.

Changes in the use of intrauterine devices (IUDs) for contraception in China in the past 10 years are reviewed. Replacement of the inert stainless steel ring with copper-bearing IUDs was an essential decision to improve the efficacy of the IUDs. The most commonly used, TCu380A, TCu220C and MLCu375, and those developed in China, such as the uterine-shaped UCu300 IUD and gamma Cu380 IUD, are reviewed. Studies of MLCu375 and TCu380A for emergency contraception revealed a highly effective method, which could prevent over 96% of unwanted pregnancies. Use of levonorgestrel-releasing system provides both contraceptive and therapeutic effects in the treatment of menorrhagia.

Intrauterine devices.

The aim of this chapter is to review the worldwide use of intrauterine devices (IUDs) for contraception and the long-term contraceptive efficacy and safety of copper-bearing IUDs. The TCu380A and Multiload Cu375 have a very low failure rate (0.2-0.5%) over 10 years. The main concerns of the use of IUDs are risk of pelvic inflammatory diseases and increased menstrual blood loss and irregular bleeding. Factors associated with an increase in risk of pelvic inflammatory diseases are discussed. Preventive measures can be taken with careful screening of eligible IUD users, technical training and adequate service facilities for provision of IUDs. Levonorgestrel-releasing IUDs have the benefit of reducing menstrual blood loss in addition to high contraceptive efficacy. The copper IUD is the most effective method for emergency contraception. It can prevent over 95% of unwanted pregnancies within 5 days of unprotected intercourse.

Combined estimates of effectiveness of mifepristone 10 mg in emergency contraception.

The present paper combines the estimates of efficacy and side effects of 10 mg mifepristone for emergency contraception obtained from randomized trials. A total of 6083 women participating in 12 randomized trials and receiving 10 mg mifepristone for emergency contraception up to 120 h after intercourse, were analyzed for efficacy. Between 4188 and 5833 women were analyzed for side effects and 3601 for delay of menses of more than 7 days. Prevented fractions, the effect of delay and of further acts of intercourse after treatment administration were analyzed in 3440 women, using individual data. The combined pregnancy rate from all the 12 trials was 1.7% [101/6083, 95% confidence interval (CI): 1.3-2.2]. From the three trials providing individual data, the combined pregnancy rate was 1.3% (45/3440, 95% CI: 0.9-1.7) and the estimate of pregnancies prevented was 83.4% (95% CI: 77.4-87.8). There was a sharp decline in efficacy when treatment was administered during the 5th day after intercourse compared to administration during the 1st day, the odds of pregnancy increasing by a factor of 5.3 (95% CI: 1.9-14.9). The relative risk of pregnancy was about 28 times higher among women with unprotected acts of coitus between treatment administration and the onset of next menses, compared with women reporting none [odds ratio (OR) = 27.6, 95% CI: 12.7-60.2]. The increase in risk for women reporting protected acts of intercourse during this interval was not statistically significant (OR = 1.8, 95% CI: 0.9-3.8). There was a large heterogeneity among trials in all side effects and delay of menses of more than 7 days (all had p < 0.0001 for the test of homogeneity). The percentage of women with nausea ranged from 0.0-19.4% (highest upper 95% confidence limit: 23.0%), that of vomiting from 0.0-4.3% (highest upper 95% confidence limit: 6.1%), that of lower abdominal pain from 4.3-19.1% (highest upper 95% confidence limit: 22.7%). The percentage of women with delay of menses of more than 7 days ranged from 4.3-25.8% (highest upper 95% confidence limit: 34.1%). We conclude that 10 mg mifepristone is an effective emergency contraception regimen, with an acceptable side-effects profile. Postponing treatment until the 5th day seriously decreases efficacy. The risk of pregnancy is dramatically increased among women having unprotected acts of intercourse between treatment administration and the onset of next menses. This risk may be enhanced for women whose ovulation is postponed by treatment.

Meta-analyses of randomized trials comparing different doses of mifepristone in emergency contraception.

There is some evidence from randomized trials that different doses of mifepristone for emergency contraception do not differ in efficacy in the range from 10 mg to 600 mg. Lower doses have a better side effect profile and are cheaper and therefore they would be preferable in the absence of a dose effect. However, the lack of significance is not evidence of absence of an effect. More evidence can be obtained by combining results of trials. We present meta-analyses of randomized trials comparing doses of mifepristone for emergency contraception from 5 mg to 600 mg, with regard to the efficacy to prevent unwanted pregnancies. We use two approaches for analysis, one using only within-trial information and another one combining within-trial with between-trial information. We discuss the results in terms of equivalence. There is some evidence of a small dose effect on efficacy in the lower range of doses (<50 mg). The pregnancy rate increases by a factor of 1.6 when the dose of 10 mg is used instead of 25 mg (95% confidence interval: 1.1-2.4). In terms of the number of women needed to treat, however, using 10 mg in the place of 25 mg implies having one extra pregnancy every 146 women requesting emergency contraception, which might be a low cost compared to the benefit of more women having access to treatment.

Conception probabilities at different days of menstrual cycle in Chinese women.

OBJECTIVE: To investigate the conception probability among Chinese women. DESIGN: Prospective observational study. SETTING: Clinics in hospitals and family planning institutes in 10 provinces and cities. PATIENT(S): A total of 851 healthy married women aged 18-35 years with normal menstrual cycles who wish to have babies and with no contraception. INTERVENTION(S): Urinary LH was measured around days of expected ovulation for 7 days. The Barrett and Marshall model was used for calculation of conception probabilities on each cycle day from day -5 to day +1 in women with multiple episodes of intercourse. MAIN OUTCOME MEASURE(S): Pregnancies in 1, 3, and >or=6 months. RESULT(S): A total of 851 women with 2,055 cycles were analyzed. In 489 cycles there was only one episode of intercourse. A total of 601 pregnancies occurred. The conception probabilities from days in relation to ovulation -5 to +1 for a single episode of intercourse were 0.216, 0.102, 0.236, 0.233, 0.388, 0.293, and 0.386, respectively, and for multiple episodes they were 0.254, 0.271, 0.293, 0.365, 0.315, and 0.284, respectively, with the peak value at day -1. Recalculation of the efficacy of emergency contraception with low-dose mifepristone with the present conception probabilities showed higher efficacy. CONCLUSION(S): Conception probabilities among Chinese women are different from those in the literature. Further comparative studies are needed to confirm an ethnic difference.