Table 2. Comparison of hatched rates between ‘8’-shape and ‘U’-shape hatching blastocysts.

	In vivo developed group %		In vivo fertilization and embryo culture %		In vitro fertilization and embryo culture %
Hatching type	Hatched	Un-hatched	Hatched	Un-hatched	Hatched	Un-hatched
‘8’-shape	0 (0/2) a	100 (2/2)	3 (2/66) b	97 (64/66)	3.6 (2/56) c	96.4 (54/56)
‘U’-shape	89.5 (188/210) a	10.5 (22/210)	79.8 (134/168) b	20.2 (34/168)	73.4 (127/173) c	26.6 (46/173)

‘8’-shape = ‘8’-shaped hatching blastocyst with small opening of zona pellucida; ‘U’-shape = ‘U’-shaped hatching blastocyst with large opening of zona pellucida. Hatched = the blastocyst finished hatching and escaped the zona pellucida. Un-Hatched = the blastocyst started hatching but did not escape the zona pellucida. All the percentages are the fractions based on the total number of ‘8’-shaped or ‘U’-shaped hatching blastocysts of each group.

^{a, b, c} Values with the same superscripts are significantly different (P < 0.05, χ²-test).