The association between the number of oocytes retrieved and cumulative live birth rate in different female age strata

Abstract

To evaluate the association between the number of oocytes retrieved and cumulative live birth rate (CLBR) in different female age strata. 17,931 women undergoing their first IVF/ICSI-ET cycle in the Sir Run Run Shaw Hospital of Zhejiang University were grouped by age (A: ≤ 35 years; B: ≥ 36 years) as well as the number of oocytes retrieved (a: ≤ 5; b:6–9; c:10–14; d: ≥ 15). Multivariate regression analysis was performed to assess the OR of CLBR for the variable ‘age’ and ‘number of oocytes retrieved’. The group ≥ 36 years exhibited lower cumulative pregnancy rates (CPRs) and cumulative live birth rates (CLBRs), which are proportional to the number of oocytes retrieved but opposite to increasing age. Multivariate logistic regression analysis revealed that the age and number of oocytes retrieved remain significant independent predictive factors (P < 0.001). Age and number of oocytes retrieved are two independent factors affecting the CLBR. The discrepancy of the minimum number of oocytes retrieved for patients with different ages to achieve ideal CLBR is instructive for clinical practice. The practice of controlling the stimulation dose is feasible for patients ≤ 35 years who can achieve over 60% CLBR once the number of oocytes obtained is more than 6. However, additional stimulation cycles and accumulation of embryos are necessary for elderly group especially those ≥ 38 years old who need more than 14 oocytes to obtain higher live birth rate.