| BackgroundThe objective of assisted reproductive technology(ART)is to obtain a pregnancy and finally a healthy life birth.During this progress,oocyte retrieval is one of the most important steps.The oocyte retrieval rate is an index to measure whether the number of oocytes obtained has reached the maximum.It can also be used to evaluate the oocyte recovery efficiency.The expected range of oocyte retrieval rate is 80%95%.Previous study showed it does not affect the clinical pregnancy rate in fresh embryo transfer cycles when oocyte retrieval rate is greater than 50%.However,few studies has focused on the effect of live birth rate,especially based on a large sample size.Therefore,in this study,we recruited nearly 20,000 cycles to investigate the distribution of oocyte retrieval rate,analyze the risk factors affecting oocyte retrieval rate and find out its effect on live birth rate.MethodsIn this trial,we recruited 18907 patients who underwent their first in vitro fertilization(IVF)or intracytoplasmic sperm injection(ICSI)treatment in the Center for Reproductive Medicine,Shandong University from 2017 to 2019.The oocyte retrieval rate was calculated by the ratio of the number of oocytes to the number of follicles with a diameter≥14 mm on the trigger day.Percentile method(5%as reference range)was carried out to calculate the cut-off value(53.33%).According to this value,18893 patients were divided into two groups:group A,low oocyte retrieval rate(less than 53.33%,n=935)and group B,normal oocyte retrieval rate(greater than 53.33%,n=1 7958).Two independent sample t-test,Mann Whitney U-test,chi square test and binary logistic regression were used to compare ovarian stimulation protocols,laboratory indexes and pregnancy outcomes between groups A and B.Results1)There were11380 patients with oocyte retrieval rate ≥ 100%,accounting for 60.19%;There were 4593 patients with oocyte retrieval rate of 75%～100%,accounting for 24.29%;There were 2372 patients with oocyte retrieval rate of 50%～75%,accounting for 12.55%;There were 920 patients with oocyte retrieval rate less than 50%,accounting for 2.97%;And there were 31 patients with failed oocyte retrieval(i.e.empty follicles),accounting for 0.16%of the total.2)The pregnancy outcomes between group A and group B:biochemical pregnancy rate(57.25%vs 64.8%,Padj=0.002,ORadj 1.345,95%CI 1.117-1.62),clinical pregnancy rate(49.41%vs 56.96%,Padj=0.002,ORadj1.334,95%CI 1.111-1.601)and live birth rate(40%vs 47.08%,Padj=0.004,ORadj 1.313,95%CI 1.089-1.582),in which,group A were significantly lower than group B.The laboratory indexes in group A which were also lower than those in group B(P<0.001)include:the oocyte maturation rate(86.4%vs 88.77%),the number of normal fertilized eggs(2.31±1.96 vs 7.4±4.06),normal fertilization rate in IVF cycle(82.84%vs 79.23%),the number of high-quality embryos(1.32±1.48 vs 4.16±3.09)and the number of fresh embryo transfer(1.51±0.5 vs 2.03±0.47).However,there was no significant difference between normal fertilization rate in ICSI cycle and high-quality embryo rate.3)The risk factors affecting oocyte retrieval rate include:age,body mass index(BMI),ovarian reserve and ovulation inducing protocols.After adjusting for confounding factors such as age,BMI,basic follicular stimulating hormone(FSH),anti-Mullerian hormone(AMH)and ovulation inducing protocols,patients in group A had the longer duration of Gn stimulation(10.28±2.66 vs 10.01±2.34,P=0.001,OR 1.092,95%CI 1.039-1.15),the higher starting dose of Gn(188.36±72.62 vs 174.55±59.3,P=0.01,OR 1.002,95%CI 1.001-1.004),the higher dose of human chorionic gonadotropin(hCG)(7985.03±1342.67 vs 7357.43±1593.73,P=0.041,OR 0.999,95%CI 0.9998-1.000)and the shorter time interval between hCG injection and oocyte retrieval(36.36±3.09 vs 36.78±0.71,P<0.001,OR 0.86,95%CI 0.824-0.899).ConclusionAmong the patients in our center,the reference value of 5%on one side is 53.33%,when the oocyte retrieval rate is lower than 53.33%,the pregnancy outcomes get worse and the live birth rate is significantly reduced.In addition to age,BMI,ovarian reserve,and ovulation inducing protocols,the dosage and duration of Gn and hCG may also be the influencing factors of oocyte retrieval rate. |
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