Luukkainen T, Nilsson C G
Contraception. 1978 Oct;18(4):451-4. doi: 10.1016/0010-7824(78)90029-x.
Clinical experience with seventy-two first insertions of a d-norgestrel-releasing IUD is reported. Plasma d-norgestrel concentrations were measured in twelve subjects. No pregnancies occurred in the 522 woman-months of use (averaging 7.3 months/subject) that have been accumulated. Removals were performed in six subjects for medical reasons and in seven subjects for personal reasons. Plasma concentrations of d-norgestrel were highest during the first two weeks of use. A decline in the plasma concentration of d-norgestrel occurred and was only 0.05 ng/ml between 30 and 90 days after insertion.
报告了72例首次植入含左炔诺孕酮宫内节育器的临床经验。对12名受试者测量了血浆左炔诺孕酮浓度。在累积的522个妇女使用月（平均每名受试者7.3个月）中未发生妊娠。6名受试者因医学原因取出，7名受试者因个人原因取出。左炔诺孕酮的血浆浓度在使用的前两周最高。左炔诺孕酮的血浆浓度出现下降，在插入后30至90天之间仅为0.05 ng/ml。
