. 2017 Apr 6;12(4):e0175150. doi: 10.1371/journal.pone.0175150

Table 1. Rate and median of inside/outside collapse in “8”-shaped-hatching, U-shaped-hatching, and unhatched blastocysts.

		“8”-shaped hatching (n = 74)	U-shaped hatching (n = 12)	Unhatched (n = 9)
Inside collapse	Rate	0.0% (0/74)^a	8.3% (1/12)^a	44.4% (4/9)^a
Inside collapse	Median (IQR)	0 (0–0)	0 (0–0)	0 (0–1)^b
Outside collapse	Rate	86.5% (64/74)	-	-
Outside collapse	Median (IQR)	2 (1–4)^b	-	-

^a The rate of inside collapse was higher in unhatched blastocysts than in other blastocysts (P = 0.0020, Fisher’s exact test).

^b Outside collapse in “8”-shaped-hatching blastocysts occurred significantly more frequently than inside collapse in unhatched blastocysts (P = 0.0007, Mann–Whitney U test).