A randomized trial to compare 24 h versus 12 h double dose regimen of levonorgestrel for emergency contraception

Authors: Wai Ngai, Suk¹; Fan, Susan²; Li, Shiqin³; Cheng, Linan⁴; Ding, Juhong⁵; Jing, Xiaoping⁶; Yu Ng, Ernest Hung⁷; Chung Ho, Pak¹

Source: Human Reproduction, Volume 20, Number 1, 1 January 2005 , pp. 307-311(5)

Publisher: Oxford University Press

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Abstract:

BACKGROUND: Levonorgestrel (0.75 mg given for two doses 12 h apart) has been proven to be an effective regimen for emergency contraception when the first dose is given within 72 h of unprotected coitus. However, the dosing interval is inconvenient for those taking the first dose in the afternoon. We conducted a randomized study to evaluate two levonorgestrel dosing regimens for emergency contraception. Two doses of levonorgestrel 0.75 mg were administered with the first dose given up to 120 h after unprotected intercourse. The second dose was given 12 h later in the first regimen and 24 h later in the second regimen. METHODS: We conducted a double-blind, randomized trial between 1997 and 2003 at five centres in China. A total of 2071 women requesting emergency contraception within 120 h of unprotected intercourse were recruited. They were randomized to receive two doses of 0.75 mg of levonorgestrel, given either 24 h apart or 12 h apart. RESULTS: Outcome was unknown for 53 women (24 in the 24 h group and 29 in the 12 h group). Among the remaining 2018 women, the crude pregnancy rate was 1.9% in the 24 h group [95% confidence interval (CI) 1.17–2.94] and 2.0% in the 12 h group (95% CI 1.19–2.99). The proportion of pregnancies prevented was estimated to be 72% in the 24 h group and 75% in the 12 h group. Side-effects were mild in both groups. The efficacy of the 12 h regimen declined significantly when there were further acts of intercourse after treatment (5.0 versus 1.0%, P<0.01). This was not observed in the 24 h group. CONCLUSIONS: Two doses of 0.75 mg levonorgestrel given either 24 or 12 h apart are effective for emergency contraception up to 120 h after unprotected intercourse. Further research to investigative more effective methods of emergency contraception is warranted.

Keywords: emergency contraception; levonorgestrel; pregnancy; randomized trial; unprotected intercourse

Document Type: Research article

DOI: http://dx.doi.org/10.1093/humrep/deh583

Affiliations: 1: Department of Obstetrics & Gynecology, University of Hong Kong, Queen Mary Hospital, 102 Pokfulam Road, Hong Kong SAR, 2: MRCOG, Family Planning Association of Hong Kong, Hong Kong SAR, 3: Family Planning Association, Institute of Shenzhen, 4: Shanghai Institute of Family Planning Technical Institution, 5: Jiangsu Family Planning Institute, 6: Beijing Chaoyang Hospital, affiliated to Capital University of Medical Science and 7: Department of Obstetrics & Gynecology, University of Hong Kong, Hong Kong SAR, China

Publication date: 2005-01-01

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Human Reproduction features full-length, peer-reviewed papers reporting original research, clinical case histories, as well as opinions and debates on topical issues. Papers published cover the scientific and medical aspects of reproductive physiology and pathology, endocrinology, andrology, gonad function, gametogenesis, fertilization, embryo development, implantation, pregnancy, genetics, genetic diagnosis, oncology, infectious disease, surgery, contraception, infertility treatment, psychology, ethics and social issues. The highest scientific and editorial standard is maintained throughout the journal along with a rapid rate of publication.

A randomized trial to compare 24 h versus 12 h double dose regimen of levonorgestrel for emergency contraception

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