  In many developing countries, timely and accurate information about birth
rates and other demographic indicators is still lacking, especially for male
fertility rates. Using anonymous and aggregate data from Facebook's Advertising
Platform, we produce global estimates of the Mean Age at Childbearing (MAC), a
key indicator of fertility postponement. Our analysis indicates that fertility
measures based on Facebook data are highly correlated with conventional
indicators based on traditional data, for those countries for which we have
statistics. For instance, the correlation of the MAC computed using Facebook
and United Nations data is 0.47 (p = 4.02e-08) and 0.79 (p = 2.2e-15) for
female and male respectively. Out of sample validation for a simple regression
model indicates that the mean absolute percentage error is 2.3%. We use the
linear model and Facebook data to produce estimates of the male MAC for
countries for which we do not have data.
