Elective single blastocyst-stage transfers (n=240)
Double blastocyst-stage transfers (n=189)
P-value
Female age (years) 37.4 ± 1.8 38.1 ± 2.1 0.001
36-37, n (%) 152 (63.3) 95 (50.3) 0.006
38-39, n (%) 61 (25.4) 54 (28.6)
≥40, n (%) 27 (11.3) 40 (21.2)
BMI (kg/m2) 22.9 ± 2.9 23.2 ± 2.9 0.279
Primary infertility, n (%) 44 (18.3) 38 (20.1) 0.643
Infertility duration (years) 4.1 ± 3.5 4.9 ± 4.4 0.05
Rank of cycle, Median (range) 1 (1-3) 1 (1-4) <0.001
Level of education, n (%)
Primary school or lower 19 (7.9) 14 (7.4) 0.389
Secondary school 141 (58.8) 123 (65.1)
University or higher 80 (33.3) 52 (27.5)
Infertility diagnosis, n (%)
Tubal factor 123 (51.2) 97 (51.3) 0.098
Ovulatory dysfunction 9 (3.8) 17 (9.0)
Endometriosis 4 (1.7) 1 (0.5)
Male factor 35 (14.6) 34 (18.0)
Unexplained 20 (8.3) 11 (5.8)
Multiple factors 49 (20.4) 29 (15.3)
Year of oocyte retrieval, n (%)
2015 26 (10.8) 41 (21.7) <0.001
2016 40 (16.7) 48 (25.4)
2017 66 (27.5) 35 (18.5)
2018 108 (45.0) 65 (34.4)
Insemination methods, n (%)
IVF 195 (81.3) 150 (79.4) 0.600
ICSI 39 (16.3) 31 (16.4)
Mixed IVF and ICSI 6 (2.5) 8 (4.2)
No. of oocytes retrieved 11.5 ± 4.0 11.1 ± 4.1 0.184
No. of 2PN 8.2 ± 3.1 7.9 ± 3.3 0.359
No. of viable embryos 7.5 ± 2.8 7.3 ± 3.1 0.486
Total blastocysts per patient 4.9 ± 2.0 4.4 ± 2.3 0.011
Good-quality, n (%) 159 (66.3) 48 (25.4) <0.001
No. of supernumerary blastocysts for vitrification 3.9 ± 2.0 2.4 ± 2.3 <0.001