Table 4. Diameter-dependent progression of live birth rates within each blastocyst quality grade
Quality grade Diameter group n Live birth rate, % (n) Trend p-value
Best ≤180μm
180-200μm
>200μm
24
54
92
29.2 (7)
44.4 (24)
50.0 (46)
0.036
Good ≤180μm
180-200μm
>200μm
48
77
96
27.1 (13)
39.0 (30)
37.5 (36)
0.043
Fair ≤180μm
180-200μm
>200μm
48
22
15
14.6 (7)
27.3 (6)
33.3 (5)
0.049
Overall ≤180μm
180-200μm
>200μm
120
153
203
22.5 (27)
39.2 (60)
42.9 (87)
<0.001

Trend p-values calculated using Cochran-Armitage test for ordered proportions