Pre-transitional countries are found mustly in Africi, with some others in South Asia, the Middle East, Oceania, and Latin America. Life expectancy is generally low; in this group, it surpasses 60 years only in a few Middle Eastern and North African countries. With a few exceptions, the countries in this group are classified by the World Bank as low- and lower-middle iacome countries.

Transitional countries. Current fertility in countries in transition vanies considerably because fertility decline may have just started or may be continuing a trend started as long as two decades ago. Figure lb portrays representative countries over the period 1950-85, &'- wing the decline from a-gh levels of fertility to transitional fertility. TFRs at the start of the transition were quite dissimilar, from 7.2 (Algeria) to 5.0 (Trinidad and Tobago), and cfrrent TFRs continue to show a wide spread. This grapn also shows that the rate of fertility decline varies: the average annual change for Trinidad and Tobago (-.006) for the period 1975-85 is considerably snaller than the annual change for Algeria (-.017).

For these transitional countries, v- .irst attempted to determine the average annual fertility decline. Second, we examined trends to determine whether these declines were linear. Third, we looked at the deterninants of the pace of fertility decline.

Three alternative data sets were used to determine average decline. Of the 59 transitional countries in Table 1, we initially selected those 49 w;th total fertility of three or higher in 1985-90. The lower-fertility countries were left out with the intention of treating separately the slowing of ferility decline toward the end of transition. The mean annual decline in total fertility in these countries from 1980-85 to 1985-90, using World Bank estimates, was .09 points.

An attempt was made to validate this result with a second data set. For 32 countries that started fertility transition at least ten years previously, survey, census, or registration data were assembled from U.S. Bureau of the Census (1979), World Fertility Surveys, contraceptive prevalence surveys, or Demographic and Healt. Surveys, covering at least three time points-and often many more-after the start of fertility transition. Average annual declines in fertility were obtained for each country by linear regression. Across countries, the mean annual decline was .15, substantially higher than the first figure.

In an attempt to reconcile the two figures, we carefully examined the Bank fertility estimates. Instead of using the quinquennial estimates, we interpolated to obtain total fertility rates in the years that fertility transition started, as well as exactly 10, 15, or 20 years later (depending on how long ago fertility transition started). This procedure was applied to the 32 countries covered in the previous procedure, as well as to 10 other countries with sufficiently early transitions but insufficient data to be included in the previous data set. In this set of estimates, the largest fertility declines, of close to .20 points annually over 15 to 20 years, were for Singapore, and Mexico. The smallest declines, of .05 to .08 points annually, were for Fiji, the United Arab Emirates, and Sri Lanka. The mean annual decline across countries was .13 for all 41 countries, or .14 for the 32 countries in the previous data set.

Figure 2 shows the distribution of countries ' heir average declines in the third data set, as well as the distribution of declines recorded in the first and second decades after the start of transition. Declines in the second decade tend to be slightly slower. (Particularly for countries with very rapid initial declines, two decades is enough to bring TFR within one point of .eplacement fertility.) This may partly explains the discrepancies among the results. The first data set, with the mo,st recent data, has proportionally more cases of late transition and therefore has a lower avenge. The estimates from the three data sets may also differ for a variety of other reasons, including selectivity, differences in typical declines in different decades, and differences in the specific years covered by estinates. The results from the latter two data sets agree in the aggregate, and, as Figure 3 shows, tend to roughly agree for individual countries. In this figure, average declines estimated from the two data sets are plotted against each other. Most points cluster around the line along which estimates are equal. However, declines based on Bank estinates tend to be slightly more moderate, less extreme in either direction.

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