Table 1 Baseline characteristics of embryo transfer cycles with and without assisted hatching (AH). ART, assisted reproductive technology; SMD, standardized mean difference. SMD is shown as an absolute value. * Indication for ART allows overlapping items, and those that do not fall under any indication are classified as unexplained.

From: Effect of assisted hatching on pregnancy outcomes following 1,678,872 single embryo transfers based on the Japan Assisted Reproductive Technology Registry

 

AH (n = 924,142)

Non-AH (n = 754,730)

SMD

Cycles

(%)

Cycles

(%)

Unweighted

Weighted

Maternal age (years)

 <35

246,696

26.7

223,386

29.6

0.065

< 0.01

 35–39

362,298

39.2

299,072

39.6

< 0.01

< 0.01

 >40

315,148

34.1

232,272

30.8

0.071

< 0.01

Type of embryo transferred

 Fresh

90,224

9.8

373,687

49.5

0.967

< 0.01

 Frozen-thawed

833,918

90.2

381,043

50.5

0.967

< 0.01

Embryo stage at embryo transfer

 Cleavage

214,820

23.2

412,110

54.6

0.679

< 0.01

 Blastocyst

709,322

76.8

342,620

45.4

0.679

< 0.01

Indication for ART treatment*

 Tubal factor

156,546

16.9

104,779

13.9

0.085

< 0.01

 Male factor

275,248

29.8

192,280

25.5

0.096

< 0.01

 Endometriosis

68,270

7.4

56,670

7.5

< 0.01

< 0.01

 Unexplained

482,020

52.2

434,170

57.5

0.108

0.010

Endometrial preparation

 Natural

49,706

5.4

63,901

8.5

0.122

< 0.01

 Progesterone

270,553

29.3

361,592

47.9

0.390

< 0.01

 Estrogen + progesterone

603,883

65.3

329,237

43.6

0.447

< 0.01

Back to article page