Segal S J, Alvarez-Sanchez F, Brache V, Faundes A, Vilja P, Tuohimaa P
Population Sciences, Rockefeller Foundation, New York, New York 10036.
Fertil Steril. 1991 Aug;56(2):273-7.
To determine if fertilization occurs unnoticed among Norplant users who are ovulatory.
Serial blood samples were obtained during 1 month from sexually active Norplant users experiencing regular menstrual bleeding patterns and a control group of noncontracepting women trying to conceive. The sequential blood samples were assayed for the presence of human chorionic gonadotropin (hCG).
All samples were obtained from women receiving contraceptive service and health care at the Center for Research and Services in Human Reproduction and Contraception, Santo Domingo, The Dominican Republic. Assays for hCG were performed at the Department of Biomedical Sciences, University of Tampere, Finland.
PATIENTS, PARTICIPANTS: A total of 32 women using Norplant implants were enrolled in the treatment group, and 20 women of proven fertility who were attempting to conceive served as a control group.
Duration of Norplant use was as follows: 4 in the 2nd year of use, 13 in the 3rd year, 11 in the 4th year, 3 in the 5th year, and 1 in the 7th year.
The determination of pregnancy was based on the presence of hCG in the luteal phase, using a sensitive and specific immunoenzymatic assay that can detect dimeric hCG as early as 7 days after ovulation.
Nine pregnancies were detected. All were in the control group trying to conceive. Six of these advanced to clinical pregnancies, and three did not proceed beyond the next expected menses. None of the Norplant users had evidence of hCG production, whether the observed cycles were anovulatory or ovulatory. The probability of finding no pregnancies in the ovulatory months at risk among Norplant users is between 1 in 50 and 1 in 150,000. The null hypothesis that Norplant users conceive at a natural rate can be rejected at the 0.05 level.
Interruption of early pregnancy (menstrual abortion) does not play a role in the mechanism of action of Norplant contraceptive implants.
确定在有排卵的诺普兰使用者中是否会发生未被察觉的受精情况。
在1个月内，从有规律月经出血模式的性活跃诺普兰使用者以及一组试图受孕的未采取避孕措施的女性对照组中获取系列血样。对连续血样进行人绒毛膜促性腺激素（hCG）检测。
所有样本均取自多米尼加共和国圣多明各人类生殖与避孕研究及服务中心接受避孕服务和医疗保健的女性。hCG检测在芬兰坦佩雷大学的生物医学科学系进行。
患者、参与者：治疗组共纳入32名使用诺普兰植入剂的女性，20名经证实有生育能力且试图受孕的女性作为对照组。
诺普兰的使用时长如下：使用第2年的有4人，第3年的有13人，第4年的有11人，第5年的有3人，第7年的有1人。
使用一种敏感且特异的免疫酶测定法，依据黄体期hCG的存在情况来确定是否怀孕，该方法可在排卵后7天最早检测到二聚体hCG。
检测到9例怀孕。均在试图受孕的对照组中。其中6例进展为临床妊娠，3例未超过下一次预期月经。无论观察到的周期有无排卵，诺普兰使用者均无hCG产生的证据。在有排卵风险的月份中，诺普兰使用者未怀孕概率在1/50至1/150,000之间。诺普兰使用者以自然受孕率受孕的原假设在0.05水平上可被拒绝。
早期妊娠中断（月经性流产）在诺普兰避孕植入剂的作用机制中不起作用。
