Prolonging hCG-Ovum Pick Up Time Can Increase Pregnancy Rates

Prolonging the hCG-ovum pickup time increased the chances of a clinical pregnancy in patients with infertility.

Increasing the human chorionic gonadotropin (hCG)-ovum pickup time can increase rates of clinical pregnancy, according to study findings published in Reproductive Biology and Endocrinology.

Assisted reproductive technology (ART) includes controlled ovarian stimulation (COS), which triggers growth in follicles and mature oocytes to increase the chance of conception. Researchers conducted a systematic review and meta-analysis to determine how the hCG-OPU interval effects ART outcomes in COS cycles. Data was collected from the CENTRAL, CNKI, Cochrane Systematic Reviews, EMBASE, MEDLINE, PUBMED, and Web of Science databases. 

A total of 591 relevant studies were identified and after exclusion, 12 studies were included in the analysis. Of these studies, 5 were retrospective cohort studies, 1 was a prospective cohort study, and 6 were randomized or quasirandomized controlled trials. All included studies with a reported association between hCG-OPU time intervals and ART outcomes were screened. Patients with infertility who underwent ART due to primary, tubal factor, male factor, or unexplained infertility treatment were included. Studies with patients who had hCG added to a culture medium instead of injecting it into the patients were excluded from the study.

Our findings encourage conducting future large, well-powered, multicenter RCTs in various countries and regions to explore the question of hCG-OPU interval and euploidy.

The typical hCG-OPU interval in most in vitro fertilization (IVF) centers was 32 to 38 hours. This study defined hCG-OPU intervals as short (33-36 hours) and long (>36-41 hours).

Across 5 studies, oocyte maturation rates were similar between the short- and long-interval groups (odds ratio [OR], 0.69; 95% CI, 0.45-1.06; I2= 91.1%). Additionally, data across 8 articles showed similar fertilization rates between the short and long-interval groups (OR, 0.88; 95% CI, 0.77-1.0; I2=44.4%).

There were 6 studies that showed similar rates between short- and long-interval groups for high-quality embryo rate (OR, 1.05; 95% CI, 0.95-1.17; I2=8.6%, respectively). 

A total of 9 studies provided information on clinical pregnancy rates. The pregnancy rates among patients in the long retrieval group were significantly higher than the short retrieval group (OR, 0.66; 95% CI, 0.45-0.95; I2=35.4%). 

Data from 3 studies revealed that the short and long-retrieval groups had a similar miscarriage rate (OR, 1.92; 95% CI, 0.66–5.60; I2=0.0%) and live birth rates (OR, 0.50; 95% CI, 0.24-1.04; I2=0.0%).

Study limitations include sample size, lack of comparative information between patients, and difficulties obtaining detailed data from other studies. 

“Our findings encourage conducting future large, well-powered, multicenter RCTs in various countries and regions to explore the question of hCG-OPU interval and euploidy,” the researchers concluded.


Gan R, Huang X, Zhao J, Zhang Q, Huang C, Li Y. Time interval between hCG administration and oocyte retrieval and ART outcomes: an updated systematic review and meta-analysis. Reproductive Biology and Endocrinology. Published online July 3, 2023. doi:10.1186/s12958-023-01110-9