英和和英

Studies of birth timing ¹ deal with the length of birth intervals ². These include the interval between marriage and the first birth ³ and intervals between successive births ⁴. The interval between a birth and a fixed date, such as that of a census (202-1 *) or survey (203-4), is called an open birth interval ⁵; intervals that begin before and end after that date are called straddling intervals ⁶. The interval between marriage and the N^th birth ⁷ is also used to study the timing of births.

• 1. Birth spacing, although sometimes found in the sense of birth timing as above, is commonly used to refer to the deliberate efforts of couples to postpone a birth.
• 3. Also called first birth intervals. The second birth interval is that between the first and the second birth; and so on.
• 4. As seen from the vantage of that census or survey, the intervals between the recorded successive births are called closed birth intervals.

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