ASSESSING AND INTERPRETING BIRTH SPACING GOALS IN COSTA-RICA

A procedure for assessing birth spacing goals, an important component of fertility preferences, is proposed and applied to 1993 Costa Rican data. Based on a reverse or backward survival analysis, preferred birt h intervals are estimated to range between 3.5 and 4.5 years (1.5 year s for the interval union to first birth). These intervals are 2 or 3 y ears shorter than crude estimates from data on open or last closed int ervals, which are upwardly biased by selection and left censoring effe cts. To achieve these spacing preferences, a cohort must spend about t wo-thirds of the time using contraception (one-third in the interval u nion to first birth). An inverse association between desired family si ze and desired birth interval is evident only in parity-specific analy ses.