Sources: Office for National Statistics, National Records of Scotland, Northern Ireland Statistics and Research Agency.
Link to the dataset: Vital statistics in the UK: births, deaths and marriages
For England and Wales, birth statistics are based on the number of births occurring in the year, while Scotland and Northern Ireland statistics relate to the number of births registered in the year. In England and Wales where a birth is registered too late to be included in the count for the year of occurrence, it will be included in the count for the following year. The ONS user guide to birth statistics provides information on data quality, legislation and procedures relating to birth statistics.
Mortality statistics for the UK and its constituent countries are based on deaths registered rather than deaths occurring in a calendar year. For information on the impact of registration delays, see Impact of Registration Delays on Mortality Statistics.