Is There Any Association Between the Number of Oocytes Retrieved, Women Age, and Embryo Development?

While most studies focused on the association between the number of oocytes retrieved and LBR, there is lack of analysis highlighting the effect of the number of oocyte retrieved on top quality embryo (TQE) rate in different age groups. We aimed to study the correlations between the number and ratio of TQE, as assessed by morphology only, according to the number of oocytes retrieved, and to evaluate the impact of patients' age. This was a retrospective study that includes 1639 patients who underwent 2263 IVF cycles between 2016 and 2019. Patients were categorized into four groups according to the number of oocytes retrieved: 1-3, 4-9, 10-14, or > 15 oocytes (OPU groups A-D, respectively). Another classification was according to patient's age < 35, 35-40, and > 40 years. Morphologically, TQE (both cleavage stage and blastocyst) was defined as those eligible for transfer or vitrification. TQE was assessed both as a fraction of oocytes retrieved per patients (rate) and the average TQE per number oocytes retrieved category. For all age subgroups, a negative significant association was observed between the number of oocytes retrieved and TQE rate (56.1%, 43.6%, 35.9%, and 34.3% for groups A-D, respectively). The reduction was significant up to 14 oocytes retrieved and plateau thereafter. On the other hand, TQE rate was significantly increased as women age increased, from 36.1% TQE rate in young women (< 35 years) to 40.3% for 35-40 years to 42.5% in older patients (> 40 years). Finally, a linear regression revealed a drop in TQE rate of - 0.5% for every oocyte retrieved, while an increased in TQE rate of + 0.7%, as the women age increased by 1 year. While young women are able to recruit more oocyte, including medium/low quality, older women recruit less oocytes, with good quality, as demonstrated by their higher morphologically TQE rate relative to the number of oocyte retrieved.