Number and percentage of birth registration and notification linked records linked to HES delivery records, England, 2005–2014
| Year of birth | Number of ONS birth records | Number of ONS birth records linked to HES delivery records (excluding duplicate HES delivery records) | Number of duplicate HES delivery records (ie, more than one HES delivery record per ONS birth record) | Never linked to HES delivery record | Linkage rate | Linked HES delivery records after quality assurance process | Percentage linked after quality assurance |
| 2005 | 617 613 | 582 963 | 25 188 | 34 650 | 94.4 | 571 775 | 92.6 |
| 2006 | 640 271 | 607 649 | 23 582 | 32 622 | 94.9 | 592 028 | 92.5 |
| 2007 | 659 061 | 632 039 | 27 207 | 27 022 | 95.9 | 614 542 | 93.2 |
| 2008 | 676 999 | 655 511 | 24 192 | 21 488 | 96.8 | 640 900 | 94.7 |
| 2009 | 675 330 | 657 622 | 40 575 | 17 708 | 97.4 | 642 508 | 95.1 |
| 2010 | 687 100 | 673 566 | 50 086 | 13 534 | 98.0 | 662 014 | 96.3 |
| 2011 | 688 681 | 674 751 | 45 005 | 13 930 | 98.0 | 663 135 | 96.3 |
| 2012 | 698 457 | 681 677 | 41 373 | 16 780 | 97.6 | 668 055 | 95.6 |
| 2013 | 668 433 | 651 957 | 42 656 | 16 476 | 97.5 | 641 108 | 95.9 |
| 2014 | 664 967 | 647 047 | 46 932 | 17 920 | 97.3 | 635 692 | 95.6 |
| Total | 6676 912 | 6464 782 | 366 796 | 212 130 | 96.8 | 6331 757 | 94.8 |
HES, Hospital Episode Statistics; ONS, Office for National Statistics.