Table 14


Table 14 presents legitimate live births by duration of married life for as many years as possible between 1990 and 1998.


Description of variables: Legitimate refers to persons born of parents who were married at the time of the birth in accordance with the laws of the country or area. Births of unknown legitimacy status are assumed to be illegitimate and are excluded from distributions.


Duration of married life is the number of completed years elapsed between the exact dates of first marriage of the wife and the exact date of birth of the child.  Although this table in principle shows births by total duration of married life, statistics for many countries or areas are tabulated in terms of duration of current marriage only, which is defined as the number of completed years elapsed between the exact date of current marriage and the exact date of birth of the child. This differs from duration of married life when the wife has been married more than once.  Except where otherwise indicated, 14 categories are used to classify duration (in years): under 1 year, single years from 1 to 9 inclusive, 10-14, 15-19, 20 and over and unknown.


Reliability of data: Data from civil registers of live births that are reported as incomplete (less than 90 per cent completeness) or of unknown completeness are considered unreliable and are set in italics rather than in roman type.  Table 1 and the technical notes for that table provide more detailed information on the completeness of live birth registration.  For more information about the quality of vital statistics in general, and the information available on the basis of the completeness estimates in particular, see section 4.2 of the Technical Notes.


Limitations: Statistics on legitimate live births by duration of married life are subject to the same qualifications which have been set forth for vital statistics in general and birth statistics in particular as discussed in section 4 of the Technical Notes.


The reliability of data, an indication of which is described in the above paragraph, is a very important factor in considering the limitations. In addition, some live births are tabulated by date of registration and not by date of occurrence, these have been indicated by a (+).  Whenever the lag between the date of occurrence and date of registration is prolonged and, therefore a large proportion of the live-birth registrations are delayed, birth statistics for any given year may be seriously affected. 


Another factor that limits international comparability is the practice of some countries or areas not to include in live-birth statistics infants who were born alive but died before registration or within the first 24 hours of live, thus underestimating the total number of live births.  Statistics of this type are footnoted.


Variations in the national definitions of “legitimate” on which the data are based contribute on important element to non-comparability.  Among countries and areas the legal basis for establishing legitimacy differs, including the types of union that establish legitimacy.  For detail discussion of these factors, see the technical notes for table 13.


A major source of non-comparability of the data in this table is that some countries or areas have tabulated legitimate live births in terms of total duration of married life and others in terms of duration of current marriage.  As has been noted above, the two concepts are not the same when the wife has been married more than once.  To the extent possible, all data in this table have been footnoted indicating whether they are based on total duration of married life or duration of current marriage.


The effect of these two methods of defining duration is that, for women married more than once, a birth occurring early in the second marriage would be shown as occurring in a higher-duration category using a duration of married life concept than it would be if the same birth were classified in terms of current marriage concepts.  The greater the difference in time between date of first marriage and date of current marriage, the greater the potential impact of this source of non-comparability.


Coverage: Legitimate live births by duration of married life are shown for 51 countries or areas.


Earlier data: Legitimate live births by duration of married life have been shown previously in issues of the Demographic Yearbook featuring natality.  For information on years covered, readers should consult the Index.