Models of contemporary Dutch family building.

Summary Recent data suggest that the level of use of oral contraceptives in the Netherlands is perhaps the highest in the world. Moreover, the greatest recent change in family building patterns is the tendency of newly weds to postpone their first birth. A micro-simulation model was developed to test the effect on fertility of such a change. An attempt was made to employ input data compatible with conditions obtaining in the Netherlands, and the distributions of family building patterns were based on recent survey evidence. The aim was not to duplicate Dutch fertility, but rather to estimate the range over which marital duration-specific fertility can be expected to vary with an increase in the proportion of couples who space their first birth. Such an increase was found to lower fertility dramatically after five years of marriage, although completed fertility was seen to vary very little. This result indicates the care that must be taken in ascribing a decline in the fertility of the early years of marriage to an overall fertility decline.