All births in England linked to delivery HES records by multiplicity, 2005–2014.
| Sex of baby | Number of ONS birth records | Linked to HES delivery record | Never linked to HES delivery record | Linkage rate |
| Singletons | 6468 586 | 6268 013 | 200 573 | 96.90 |
| Multiples | 208 326 | 196 769 | 11 557 | 94.45 |
| Total | 6676 912 | 6464 782 | 212 130 | 96.82 |
3928.081999 Pearson χ 2 statistic.
1 <- df = (rows−1)× (columns−1).
0.0000 <- getting the P value from the χ2 statistics and the df.
HES, Hospital Episode Statistics; ONS, Office for National Statistics.