Table 2 Pregnancy outcomes with and without assisted hatching (AH) before propensity score weighting. P-values for categorical variables were obtained using the chi-squared test.
| Â | AH (924,142 cycles) | Non-AH (754,730 cycles) | Risk difference (%) | P value | ||
|---|---|---|---|---|---|---|
Cycles | (%) | Cycles | (%) | |||
Primary outcomes | ||||||
 Clinical pregnancy | 302,918 | 32.78 | 211,570 | 28.03 | 4.75 | < 0.0001 |
 Live birth | 214,555 | 23.22 | 153,375 | 20.32 | 2.89 | < 0.0001 |
Secondary outcomes | ||||||
 Miscarriage | 78,788 | 26.01 | 50,981 | 24.10 | 1.91 | < 0.0001 |
 Ectopic pregnancy | 1746 | 0.19 | 1760 | 0.23 | -0.04 | < 0.0001 |
 Placenta previa | 2334 | 1.09 | 1858 | 1.21 | -0.12 | 0.0005 |
 Placenta accreta spectrum | 1821 | 0.85 | 689 | 0.45 | 0.40 | < 0.0001 |
 Multiple pregnancy | 4025 | 1.33 | 2336 | 1.10 | 0.22 | < 0.0001 |
