紧急避孕效果评价的可信性研究

目的探索以月经周期和末次月经推算受孕期与生化诊断间出现差异的原因,进而评价紧急避孕效果判断的可信性.方法对100例要求紧急避孕服务的妇女末次月经日期、月经周期和未保护性生活时间的确信程度进行回忆问卷调查,同时以B超作为月经周期、排卵监测手段进行对比性研究.结果51例(52.04%)妇女确信知道末次月经的日期;9例(9.18%)妇女不能准确回忆无保护性生活时间;58.16%的妇女在该研究周期中有过1次以上的性生活;32例(32.65%)妇女B超证实与她们的周期不符合;2例妊娠,其中1例根据Wilcox方法评估其妊娠危险概率为0%.结论对于一部分妇女依赖于对末次月经、性生活时间的回忆和排卵日的推算来评价紧急避孕效果的方法显然是不准确的,应采用更合理的评价方法.     

阴道超声检查对需要紧急避孕妇女的意义

为探究对于要求紧急避孕的妇女,经阴道超声是否较单纯的月经史更能准确的估算其非意愿性妊娠的发生率。选取在Siena大学妇产科就诊要求性交后避孕的妇女163例,收集非保护性生活的时间和月经史的资料,超声下监测卵泡和黄体的直径、子宫内膜的超声特征及其厚度、腹腔液量,以确定性交日在月经周期中的位置。本研究使用Yuzpe紧急避孕方案即己烯雌酚0.1mg加左炔诺孕酮0.5mg口服,12h后重复1次或左炔诺孕酮0.75mg,12h后重复1次。结果:本研究中有48例妇女(29.4%)提供的月经周期时间与经阴道超声确定的时间相差48h以上。若妊娠率的结点值为<0.03,用…     

10mg米非司酮紧急避孕102例临床观察

目的:观察10mg米非司酮用于紧急避孕的效果、副反应及对月经的影响。方法:对无防护性生活5天以内的102例要求紧急避孕的妇女口服米非司酮10mg,并嘱其在服药后7~10天、月经来潮或延迟不来时随诊。结果:102例妇女中有2例妊娠,妊娠率(即避孕失败率)1.96%,其副反应及对月经影响均不明显。结论:10mg米非司酮用于紧急避孕是安全、有效的。     

广东省育龄妇女不同性生活时机对妊娠率的影响

目的:探讨广东省育龄妇女在月经周期中不同时机性生活对妊娠率的影响。方法:选择年龄21～35岁健康已婚、月经正常、有意愿怀孕的妇女。纳入研究期间不采取避孕措施,在预计排卵日前7天(-7)开始至排卵日后3天(+3),每天测尿LH、BBT等,受试者在-7～+3时间内尽可能只有1次性生活,将月经情况和确切的性生活日期记录在月经卡上。结果:纳入研究的对象共98人,观察245周期,72周期妊娠,平均妊娠率为29.39%;而在-7～+3期间仅有单次性生活的周期91个,其中15周期妊娠,平均妊娠率为23.08%。按在预计排卵日-7～+3对应的某一天性生活计算妊娠率:分别为:0、0、20%、18.75%、26.67%、34.38%、35.71%、31.25%、22.22%、20%、0。结论:在月经周期中性生活时机不同,其妊娠率有差异,以预计排卵日-3～0日期间性生活妊娠率较高。在-7～+3期间仅有单次性生活者较有多次性生活者妊娠率低。     

某医院人工流产女职工紧急避孕药物使用状况及失败原因调查

目的:调查人工流产妇女常规避孕和紧急避孕的情况,寻找紧急避孕药物服用后非意愿妊娠的原因,从而改善紧急避孕服务的模式和内容,以提高紧急避孕药物使用的有效率,降低非意愿妊娠的发生率。方法:选择接受无保护性生活或避孕失败72小时内要求紧急避孕的健康育龄妇女319名进行问卷调查,并对资料进行分析。结果:其中有13.38%的调查对象曾在妊娠周期内服用过紧急避孕药物,94.2%在无保护性生活后72h以内服药;在妊娠周期内服用紧急避孕药物前有多次无保护性生活占39.22%;服用后有无保护性生活占22.57%。84.88%的对象通过药店直接购得紧急避孕药。在获得紧急避孕药物时未得到正确使用说明占98.42%。结论:绝大多数的妇女在无保护性生活后及时服用了紧急避孕药物。造成紧急避孕失败的主要原因是未按照规范服药。建议向紧急避孕药物购买者提供正确的用药方法,以提高紧急避孕药物的有效率,减少非意愿妊娠的发生。     

上海市人工流产妇女紧急避孕药物使用状况和失败原因调查

目的:调查人工流产妇女常规避孕和紧急避孕的使用情况,寻找紧急避孕药物服用后非意愿妊娠的原因,从而改善紧急避孕服务的模式和内容,以提高紧急避孕药物使用的有效率,降低非意愿妊娠的发生率。方法:以横断面研究方式,对6家医院收取的人工流产妇女进行匿名问卷调查,并对资料进行分析。结果:共有2541名妇女填写了完整问卷。有13·06%的调查对象曾在妊娠周期内服用过紧急避孕药物,其中95·90%的服药对象在无保护性生活后72小时以内服药;在妊娠周期内服用紧急避孕药物前有多次无保护性生活的38·22%;服用后有再次无保护性生活的23·57%。85·89%的对象通过药房直接购得紧急避孕药。在获得紧急避孕药物时未得到正确使用说明的97·61%。结论:绝大多数的妇女在无保护性生活后及时服用了紧急避孕药物。造成紧急避孕失败的主要原因是未按照规范服药。建议向紧急避孕药物购买者提供正确的用药方法以提高紧急避孕药物的有效率,减少非意愿妊娠的发生。     

用复方米非司酮配伍米索前列醇避孕的临床研究

目的:探讨女性黄体期应用复方米非司酮配伍米索前列醇进行避孕的有效性和安全性。方法:选择多次无避孕性生活或无避孕性生活结束超过120 h要求紧急避孕的142例妇女,于预期月经来潮前10天内服用复方米非司酮,并于服用复方米非司酮48h后加服米索前列醇。观察是否妊娠和下次月经的情况。结果:142例妇女妊娠2例,失败率1.5%。140例均有月经来潮,黄体早期组开始出血时间显著早于其他两组(P0.05),出血持续时间3组间无显著性差异,与正常月经经期基本一致。结论:在黄体期使用复方米非司酮配伍米索前列醇,是一种安全、有效的避孕补救方法。     

紧急避孕知多少

一、什么是“紧急避孕” 紧急避孕是指那些在无防护性生活后几小时或几天内，女方为防止妊娠而使用的一种临时性补救措施。紧急避孕在月经周期的任何时间都可以使用。它是通过干扰妇女生殖周期而起作用，进行阻止或延期排卵，干扰受精和阻止受精卵植入。     

紧急避孕

在我们的日常生活中,一些妇女经常遇到这样的情况:漏服口服避孕药;性生活时避孕套滑脱或破裂;安全期计算失误;性生活时未采取避孕措施;或者个别妇女遭到了强暴等等。当这些意外事件发生后,她们会因惊恐发生非意愿妊娠而寝食不安、束手无策,只能消极地等待月经的来潮。而近年来开展的紧急避孕服务则可以为这些妇女排忧解难。紧急避孕方法就是针对妇女没有采取防护措施的性生活或者避孕失败后采用的一种“紧急”补救措施,以预防非意愿妊娠的发生。对于大多数妇女来说,紧急避孕方     

紧急避孕后输卵管妊娠1例

<正> 资料:女,27岁,G3P1A2,服左快诺孕酮紧急避孕后34天,阴道出血14天,下腹部持续坠胀痛2天,诊断为异位妊娠。行左侧输卵管妊娠囊取出术加盆腔清理术后10天随访。患者足月妊娠剖宫产术后两年半,采取工具避孕并严格按照规定方法使用无失败。月经规律,周期28～30天,经期4～5天,量中等,无痛经史,末次月经2003年9月28日。曾于10月9日末次月经第12天无保护性生活后来所就诊要求紧急     

Estimating the efficacy of emergency contraception--how reliable are the data?

Ninety-four women attending a family planning clinic for emergency contraception (EC) were asked how certain they were of the date of their last menstrual period (LMP), of the timing of intercourse, and how many times in the cycle they had had sex. Urinary pregnanediol concentrations were analyzed in 64 women to assess whether they had ovulated before they used EC. Forty-five women were certain of the date of the LMP, the rest were not. Only four women could not accurately recall the timing of intercourse, and 60% had had intercourse more than once in the cycle. Twenty-one women had urinary pregnanediol concentrations that were inconsistent with their cycle day. Calculations of the efficacy of EC depend on knowing the timing of intercourse in relation to the estimated day of ovulation. The results of this study suggest that these calculations are likely to be inaccurate for a significant minority of women.     

Effectiveness of levonorgestrel emergency contraception given before or after ovulation--a pilot study

BACKGROUND: Although widely used, the mechanisms of action of the levonorgestrel emergency contraceptive pill (LNG ECP) are still unclear. There are increasing data to indicate that LNG is particularly effective as an ECP by interrupting follicular development and ovulation. An important outstanding question is whether it has any effect on fertilization or implantation. METHOD: Ninety-nine women participated; they were recruited at the time they presented with a request for emergency contraception. All women took LNG 1.5 mg in a single dose during the clinic consultation. A blood sample was taken immediately prior to ingestion of the ECP for estimation of serum LH, estradiol and progesterone levels to calculate the day of ovulation. The specimens were analyzed in a single batch. Based on these endocrine data, we estimated the timing of ovulation to be within a +/-24-h period with an accuracy of around 80%. Women were followed up 4-6 weeks later to ascertain pregnancy status. The effectiveness of ECP when taken before and after ovulation was determined. RESULTS: Three women became pregnant despite taking the ECP (pregnancy rate, 3.0%). All three women who became pregnant had unprotected intercourse between Days -1 and 0 and took the ECP on Day +2, based on endocrine data. Day 0 was taken as ovulation day. Among 17 women who had intercourse in the fertile period of the cycle and took the ECP after ovulation occurred (on Days +1 to +2), we could have expected three or four pregnancies; three were observed. Among 34 women who had intercourse on Days -5 to -2 of the fertile period and took ECP before or on the day of ovulation, four pregnancies could have been expected, but none were observed. We found major discrepancies between women's self-report of stage of the cycle and the dating calculation based on endocrine data. CONCLUSION: These data are supportive of the concept that the LNG ECP has little or no effect on postovulation events but is highly effective when taken before ovulation.     

Effectiveness of the Yuzpe regimen of emergency contraception by cycle day of intercourse: implications for mechanism of action

OBJECTIVE: The purpose of this study was to provide evidence about the mechanism of action of the Yuzpe method of emergency contraception by examining effectiveness by cycle day of intercourse relative to ovulation. METHODS: Through a literature search, we identified eight studies that present the number of women treated and outcome of treatment by cycle day of unprotected intercourse relative to expected day of ovulation. Using five sets of external estimates of conception probabilities by cycle day of intercourse among women not using contraception, we assessed and compared the effectiveness of the Yuzpe regimen by whether intercourse occurred on or before the second day before ovulation or afterward, and whether intercourse occurred on or before the first day before ovulation or afterward. RESULTS: In 36 of the 45 pairs of estimates of effectiveness, based on eight separate studies and the eight studies combined and five different sets of conception probabilities by cycle day, effectiveness was higher-and in most cases substantially higher-when intercourse occurred on or before the second day before ovulation (day -2) than when it occurred later. When data were stratified by whether intercourse occurred on or before the day before ovulation (day -1), effectiveness was greater when intercourse occurred early in 43 of 45 pairs. CONCLUSIONS: These results suggest that one hypothesized mechanism of action of the Yuzpe method, inhibiting implantation of a fertilized egg, is unlikely to be the primary mechanism of action.     

Effect of single administration of levonorgestrel on the menstrual cycle

BACKGROUND: Levonorgestrel (LNG) 1.5 mg administered within 72 h of unprotected coitus is an established method of emergency contraception. Currently, there is some, although incomplete, knowledge about the mechanism of action. METHODS: We administered 1.5 mg LNG peri-ovulatory to determine the effects on serum gonadotrophins, estradiol and progesterone levels. Fourteen women were studied in a pretreatment and treatment cycle; eight women (Group A) took LNG 3 days before the expected day of ovulation, while 6 (Group B) took LNG a day before the expected day of ovulation. RESULTS: The women in Group A had a significant delay in their LH peak and onset of the next menses compared with their pretreatment cycles (26.4 vs. 39.1 days, p<.05). Those in Group B had no significant changes in the endocrine parameters but there was a significant shortening of the mean cycle length in comparison with their pretreatment cycles (25.1 vs. 20.2 days). CONCLUSION: Levonorgestrel 1.5 mg acts as an emergency contraception by delaying the LH surge and interfering with ovulation. It may also disrupt corpus luteum formation causing premature luteinization of unruptured follicles.     

Summary of evidence and research needs on the use of mifepristone in fertility regulation: consensus from the conference

The conference on the use of mifepristone to reduce unwanted pregnancy, sponsored by the World Health Organization, Concept Foundation and the Rockefeller Foundation, took place in Bellagio, Italy, between 24 and 28 September 2001. The objective of the conference was to review the scientific information and to evaluate the use of mifepristone for emergency contraception, luteal contraception and menstrual induction. Mifepristone is highly effective for emergency contraception but its advantages and disadvantages in comparison with levonorgestrel need to be further studied. Data indicate that mifepristone alone or in combination with misoprostol has potential for occasional use for women seeking help following repeated unprotected intercourse and/or when the interval between intercourse and treatment is more then 120 h. Administration of mifepristone immediately after ovulation seems to be an effective contraceptive method. However, before it can be used commonly, there is a need for a simple and inexpensive method to identify the right time in the cycle. Once-a-month treatment with mifepristone and misoprostol at the expected time of menstruation is not a practical method due to bleeding irregularities and timing of treatment. Menstrual induction with mifepristone and a suitable prostaglandin analogue is highly effective. A randomized comparison with manual vacuum aspiration is, however, needed before it can be recommended for routine use.     

The research implications of the selection of a gestational age estimation method

There are three primary methods of gestational age estimation: dating based on last menstrual period (LMP), ultrasound-based dating and neonatal estimates. We review the strengths and limitations of each method as well as their implications for research. Dating based on LMP is a simple, low-cost method of estimating gestational age. Limitations associated with the use of menstrual-based dating include reporting problems such as uncertainty regarding the LMP date, possibly due to bleeding not associated with menses, as well as concerns about the incidence of delayed ovulation, which can result in invalid estimates of gestation, even for women with certain LMP dates. Given that most women in the US have at least one ultrasound during pregnancy, it is becoming increasingly common for clinicians to verify menstrual dates using early ultrasound. To calculate gestational age with the use of ultrasound, fetal measurements are compared with a gestational age-specific reference. The primary limitation of this method is the fact that the gestational age estimates of symmetrically large or small fetuses will be biased. Further, given that ultrasound references were developed using pregnancies that were dated according to reliable LMP dates, they are potentially biased in the same direction as dates calculated according to LMP. Neonatal estimates of gestational age have been shown to be the least precise dating method. To highlight the research implications of the choice of a gestational dating method, we used data from the Routine Antenatal Diagnostic Imaging with Ultrasound Study to identify risk factors for post-term delivery. Risk factors for post-term delivery are shown to vary according to the choice of a gestational dating method, suggesting that some findings are an artefact of the choice of a method rather than evidence of causality.     

单次服用25mg米非司酮用于紧急避孕的临床效果观察

对300例月经规律,未采取避孕措施或避孕失败72小时以内的妇女,单次口服米非司酮25mg,观察避孕效果、副反应及对经期和经量的影响。300例妇女中6例妊娠,按Dixon方法推算,预期妊娠数为22.983,避孕有效率73.89％。米非司酮25mg的副反应较少,仅11.7％。有不适主诉,主要为恶心,无呕吐发生。于月经前半周期服药的妇女月经推迟明显多于后半周期服药妇女(P<0.05)。低剂量米非司酮是安全有效的紧急避孕方法。     

Updated estimates of the effectiveness of the Yuzpe regimen of emergency contraception.

The purpose of this study was to provide revised estimates of the effectiveness of the Yuzpe method of emergency contraception. Through a literature search, we identified eight studies that present the number of women treated and outcome of treatment by cycle day of unprotected intercourse relative to expected day of ovulation. Using five sets of external estimates of conception probabilities by cycle day of intercourse among women not using contraception, we assessed the effectiveness of the Yuzpe regimen. The 45 estimates of effectiveness, based on eight separate studies and the eight studies combined and five different sets of conception probabilities by cycle day, ranged from a low of 56.4% to a high of 89.3%. Our preferred point estimate is that the Yuzpe regimen reduces the risk of pregnancy by 74.1%, with a 95% confidence interval extending from 62.9% to 79.2%. True effectiveness is likely to be > 74% because treatment failures (observed pregnancies) include women who were already pregnant when treated and women who became pregnant after being treated.     

Contraceptive efficacy of emergency contraception with levonorgestrel given before or after ovulation

Background

The contraceptive efficacy of emergency contraceptive pills containing levonorgestrel (LNG-EC) has been estimated in most previous studies by judging the day of ovulation from presumptive menstrual cycle data, thus providing poorly reliable estimates.

Methods

In the present study, the efficacy of LNG-EC was determined in 393 cycles by dating ovulation on the basis of reliable hormonal and ovarian parameters validated by a database constructed in a separate study. In addition, the efficacy was determined separately for cycles in which LNG-EC was given before or after ovulation.

Results

For the 148 women who had sexual intercourse during the fertile days, the overall accumulated probability of pregnancy was 24.7, while altogether 8 pregnancies were observed. Thus, the overall contraceptive efficacy of LNG-EC was 68%. Among the 103 women who took LNG-EC before ovulation (days −5 to −1), 16 pregnancies were expected and no pregnancy occurred (p<.0001). Among the 45 women who took LNG-EC on the day of ovulation (day 0) or thereafter, 8 pregnancies occurred and 8.7 were expected (p=1.00). These findings are incompatible with the inhibition of implantation by LNG-EC in women. The same cases were also analyzed using the presumptive menstrual cycle data, and important discrepancies were detected between the two methods.

Conclusion

The efficacy of LNG-EC has been overestimated in studies using presumptive menstrual cycle data. Our results confirm previous similar studies and demonstrate that LNG-EC does not prevent embryo implantation and therefore cannot be labeled as abortifacient.     

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.