Age, body weight and ovarian function affect oocyte size and morphology in non-PCOS patients undergoing intracytoplasmic sperm injection (ICSI)

The size of oocytes was previously reported to be smaller in obese women with polycystic ovary syndrome (PCOS). In the present prospective cohort study, we sought to determine whether oocyte size and morphology are associated with patient characteristics in non-PCOS women. Oocyte and oolemmal diameter were measured, enlarged perivitelline space (PVS) and ooplasmic granulation were assessed in 308 MII oocytes from 77 IVF/ICSI couples. Statistical analysis was undertaken using SAS version 9.4 (SAS institute Inc., USA). Continuous values are presented as mean ± SD and compared using a two-sample t-test or Mann-Whitney U test as appropriate. Categorical parameters are presented as proportions and compared using a Fisher exact test. Logistic and linear regression models were used to control for the effect of age for categorical and continuous variables respectively. P-value < 0.05 was considered statistically significant. Patients presented with a mean age of 40.3±5.0 years, had a BMI of 25.1±6.1 kg/m2, median AMH levels of 0.6 ng/ml and produced a median of 4 oocytes. Mean total oocyte diameter was 163.2±7.4 μm (range 145.8-182.1 μm), while oolemmal diameter was 109.4±4.1 μm (range 98.5-122.3 μm). After adjusting for age and ovarian reserve increasing BMI was associated with decreased total oocyte diameter (p