Multiple Deliveries in North Carolina: Trends and Outcomes

Objectives: The purpose of this study is to examine trends and patterns in multiple deliveries in North Carolina and to estimate the impact of increased multiple births upon the state’s low birthweight rate. Methods: Data are for white and minority deliveries (or live births) categorized by plurality, maternal age, birthweight, and age at death. A method for partitioning differences in rates is used to estimate the percentage contributions of 1) maternal age groups to the increase in multiple deliveries and 2) multiple live births to the increase in low birthweight. Results: Between 1980 and 1997, the state’s multiple delivery rate rose 40 percent, from 20.5 to 28.7 multiple deliveries per 1,000 total deliveries. The increase was particularly high among whites above age 30. A shift towards older childbearing appears to account for about one-third of the overall increase in multiple deliveries. An estimated 70 percent of the 1980-1997 increase in the state’s low birthweight rate appears to be due to increased multiple births. In 1997, almost 20 percent of all low birthweight births were multiple births, compared to 14 percent in 1980. Low birthweight and infant mortality are much higher among multiples than among single-born infants. Conclusion: Babies born of multiple gestations are far more likely than single-born babies to be of low birthweight, to have serious health problems, and to die. Older childbearing and increased use of infertility therapies have resulted in more multiple deliveries. The increase in these high-risk infants appears to account for about 70 percent of the 1980-1997 increase in the state’s low birthweight rate. Acknowledgement: The authors would like to thank Drs. Kevin Ryan and Vijaya Bapat of the N.C. Women’s and Children’s Health Section for helpful comments on this paper. SCHS Studies NORTH CAROLINA DEPARTMENT OF HEALTH AND HUMAN SERVICES A Special Report Series by the State Center for Health Statistics P.O. Box 29538, Raleigh, N.C. 27626-0538 www.schs.state.nc.us/SCHS/ North Carolina Public Health ®