Data comparability is a valuable thing, and achieving high levels of compatibility is exactly the goal of the Human Fertility Database. From the website:
The main goal of the Human Fertility Database (HFD) is to provide access to detailed high-quality data on cohort and period fertility to a broad audience of users. We are trying to develop the HFD into an important resource for monitoring, analyzing, comparing, and forecasting fertility as well as for studying causes and consequences of fertility change in the industrialized world. The uniform format of HFD data will facilitate comparative analysis across countries and regions and encourage analysts to move beyond the simple indicators such as the period Total Fertility Rates.
Great efforts are being made to ensure reliable and comparable measures of fertility. All data are based on official birth registrations, and include detailed measures such as Birth Counts, Female population exposure, Age-specific fertility rates, as well as summary indicators such as Mean ages at birth, Total fertility rates, Cumulative fertility rates, and parity progression ratios. Currently, available countries include:
What I find especially remarkable, is the free availability of the data. After registering, users can easily download the complete database, or parts of it.