Age-specific Fertility Rates (cont.)
The pattern of fertility is a very important concept in demography. As with mortality if we can be sure about the pattern (i.e. the shape) of the phenomenon and recognise the distinct ways in which it changes under certain circumstances, but also recognise features which do not readily change, then we can use the known shapes to a) check if data appears to be good quality, b) attempt to correct irregularities that we suspect are due to poor data, c) make predictions. This leads to the ability to have models of fertility and mortality – but that is dealt with in later sessions. Suffice it to say that patterns are very important in demography.
Sets of ASFRs and their associated graphs are commonly known as fertility schedules.
Fertility patterns and schedules are extremely important in demography and much time is taken examining them. Consider some patterns in Figure 2 and then return to this page.
On the following graphic, click on country names to display the fertility pattern.
Let’s try and group some patterns. I would suggest the following four patterns. Investigate these and see if you agree.
Pattern A: Very high fertility - Niger, Ethiopia, Rwanda. This shows a broad pattern with a rapidly rising pace of fertility from teenage years and a considerable spread that remains substantial even at ages 39-44yrs. This would be typical of a high fertility population that accepted childbearing from an early age (signifying early marriage) and showed little attempt to limit family size.
Pattern B: Low fertility - Netherlands, UK, Korea. Childbearing is concentrated across a narrower age-range, later than the peak in Pattern A. There is little teenage childbearing and little after age 40. This is a more “modern” pattern and, importantly, one in which there must be a considerable amount of control of fertility – by use of contraception.
Pattern C: Medium level fertility with very early start – Zimbabwe, India, Fiji. There is clearly some intentional control of fertility but a cultural preference for having children early and then limiting further children.
Pattern D: Low fertility with early childbearing – Brazil, Cuba, Russia. Low fertility comparable to Pattern B but in terms of timing more similar to Pattern C.
This leaves some countries – Morocco, Indonesia, Saudi Arabia, China – uncategorized. Have a look at these patterns and decide for yourself how they compare.
Therefore the fertility pattern can give us some clues about the extent of fertility control although this is speculative and to investigate this properly would need a contraceptive prevalence survey and/or the analysis of Parity Progression Ratios (see later).