Table 2. Baseline characteristics of study and control groups.
Study Group
(double vitrification)
Control Group
(single vitrification)
p-value
Patients (n) 252 450
Female patient mean age
(at oocyte retrieval)
33.3 (±5.7) 32.1 (±6.7) 0.007
Transferred blastocysts (n) 381 780
Good quality blastocysts 304 (80%) 680 (87%) 0.001
Mean number of embryos per ET 1.51 (±0.59) 1.73 (±0.51) 0.028
Newborns 80 212