INCREASING TRENDS IN PLURAL BIRTHS IN THE UNITED-STATES

Objective: To determine the nature and possible reasons for the increasing trend in plural births in the United States during the 1980s. Methods: We performed a descriptive analysis of births in the United States for five racial and ethnic groups from 1980-1989, using the United States vital records natality files. Results: The rates of twin and triplet births rose 19 and 100%, respectively, during the 1980s. Approximately one-fourth of the observed increases can be attributed to rising maternal age. The increases in twin and triplet births occurred mainly among more educated and older white women. Conclusion: The association of high education status with rising rates of plural births, independent of maternal age, suggests that the observed increase is the result of increasing use of fertility-stimulating therapy among a subset of the childbearing population.