Journal of Assisted Reproduction and Genetics

, Volume 28, Issue 10, pp 901–910 | Cite as

The time interval between hCG priming and oocyte retrieval in ART program: a meta-analysis




To evaluate the relationship between different hCG priming-to-oocyte retrieval intervals and assisted reproductive technology (ART) outcome.


We systematically searched PubMed, EMBASE, the Cochrane Library, Science Citation Index, Chinese biomedicine (CBM) literature database, and Chinese Journal Full-text Database for randomized controlled trials (RCTs) published up to November 2010. Data was extracted from the studies by two independent reviewers. Statistical analysis was performed with Cochrane Collaboration’s Review Manager (RevMan) 5.0.2. From extracted data, Risk Ratio (RR) with 95% confidence interval (CI) was calculated.


5 RCTs totaling 895 participants were included. Oocyte maturation rate was higher in the long interval group compared with short interval group (RR, 0.67; 95% CI, 0.62–0.73). There were no significant difference between the two groups with regard to fertilization rate (RR, 0.99; 95% CI, 0.94–1.04), implantation rate (RR, 0.91; 95% CI, 0.40–2.04), and pregnancy rate (RR, 0.79; 95% CI, 0.58–1.08).


The percentage of mature (MII) oocytes can be increased by prolonging the interval between hCG priming and oocyte retrieval. The prolonged interval could not increase the fertilization rate, implantation rate, and pregnancy rate. Although there was evidence to confirm the results, they still need to be confirmed by large-sample, multicenter, randomized controlled trials. The time interval dependent mechanisms responsible for ART performance need to be elucidated.


Human chorionic gonadotropin Oocyte retrieval Time interval Infertility Assisted reproductive technology Meta-analysis 



Assisted reproductive technology


Adenosine triphosphate


Clomiphene citrate


Controlled ovarian hyperstimulation


Embryo transfer


Follicle-stimulating hormone


Gonadotropic hormone releasing hormone analogue


Human chorionic gonadotropin


Human menopausal gonadotropin


Intracytoplasmic sperm injection


Insulin-like growth factor




Intramuscular injection


Intrauterine insemination


In vitro fertilization


In vitro maturation


Luteinizing hormone


Long interval


Metaphase II


Not available


Randomized controlled trial


Review Manager


Risk ratio


Short interval


Transvaginal ultrasound


Vascular endothelial growth factor



95% CI

95% confidence interval



The authors would like to thank Jin-Hui Tian, Bin Ma, Lei Jiang, Wen-Qin Jia, Kang Yi, and Lun Li (Evidence-Based Medicine Center of Lanzhou University, Lanzhou, China) for advice on conducting the meta-analysis and writing the article.

Conflicts of interest statement

The authors declared no conflicts of interest related to this study.


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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  1. 1.The Reproductive Medicine Centerthe First Hospital of Lanzhou UniversityLanzhouChina
  2. 2.The Evidence-Based Medicine Center of Lanzhou UniversityLanzhouChina

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