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Gynecol Endocrinol. 2014 Jun;30(6):431-7. doi: 10.3109/09513590.2014.895984. Epub 2014 Apr 14.

Timing of human chorionic gonadotropin (hCG) hormone administration in IVF/ICSI protocols using GnRH agonist or antagonists: a systematic review and meta-analysis.

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  • 1Department of Obstetrics and Gynecology, The First Affiliated Hospital of Chongqing Medical University , Chongqing , P.R. China and.



To evaluate the effect of altering the timing of human chorionic gonadotropin (hCG) administration on the clinical outcome of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) using gonadotropic hormone releasing hormone (GnRH) agonist or antagonist.


We systematically searched six databases. Randomized controlled trials (RCTs) of the effects of altering the timing of hCG administration on the clinical outcome of IVF and ICSI using GnRH agonist or antagonist were included. A meta-analysis was conducted following a quality evaluation performed with Cochrane Collaboration's Review Manager (RevMan) 5.0.2.


Seven RCTs and a total of 1295 participants were included. Significant difference was observed regarding estradiol and progesterone levels on the day of hCG administration and oocyte retrieval between early hCG and late hCG administration group and in favor of the latter. The fertilization rate was not statistically different between early and 24-h late hCG groups, but it is significantly higher in the 48-h late hCG group. The pooled results showed no significant differences in the ongoing pregnancy rate per oocyte pick-up, the miscarriage rate and the live birth rate.


The prolongation of follicular phase by delaying hCG administration could increase estradiol, progesterone levels and oocyte retrieval, which will not influence ongoing pregnancy rate per oocyte pick-up, miscarriage rate and live birth rate. Postponing hCG may enable increased flexibility of cycle scheduling to avoid weekend procedures.


GnRH agonist; GnRH antagonist; hCG; in vitro fertilization; intracytoplasmic sperm injection; meta-analysis; oocyte retrieval; systematic review

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