1. The NEW Matched Multiple Birth File, 1995 - 2000 Joyce A. Martin, MPH Brady E. Hamilton, PhD Candace M. Cosgrove, MPH Martha L. Munson, MS U.S. Department of Health and Human Services Centers for Disease Control and Prevention National Center for Health Statistics Division of Vital Statistics

2. SOURCE: CDC/NCHS The Matched Multiple Birth File Allows for research of characteristics of SETS of multiple gestation pregnancies Includes ALL records reported in twin, triplet and quadruplet deliveries from 1995-2000 NCHS birth, fetal death and linked birth/infant death files

3. SOURCE: CDC/NCHS The NEW Matched Multiple Birth File 325,516 SETS of twins 325,516 SETS of twins 12,157 SETS triplets 12,157 SETS triplets 760 SETS of quadruplets 760 SETS of quadrupletsOR > 699,000 individual records

4. SOURCE: CDC/NCHS Definition: multiple delivery A multiple delivery or multiple gestation pregnancy may include any combination of live births and fetal deaths; all products of the pregnancy which are DELIVERED at any point in the pregnancy are counted. A multiple delivery or multiple gestation pregnancy may include any combination of live births and fetal deaths; all products of the pregnancy which are DELIVERED at any point in the pregnancy are counted.

5. SOURCE: CDC/NCHS Example: 1 fetal death (≥ 20 wks) + 2 live births = 1 triplet pregnancy or triplet SET

6. SOURCE: CDC/NCHS Twin birth rate: U.S., 1980-2002 +65% 0

7. SOURCE: CDC/NCHS Triplet/+ birth rate: U.S., 1980-2002

8. SOURCE: CDC/NCHS Gestational age distribution by plurality: U.S., 2002 Twins

9. SOURCE: CDC/NCHS Mean birthweight by plurality: U.S., 2002

10. SOURCE: CDC/NCHS Infant mortality rates by plurality: U.S., combined years 1999-2001 6

11. SOURCE: CDC/NCHS Percent low birthweight for all births and for singletons: U.S., 1980-2002 0

12. SOURCE: CDC/NCHS Traditional U.S. Birth Files Infants in multiple deliveries Unmatched

13. SOURCE: CDC/NCHS Matched Multiple Birth File Infants in multiple deliveries

14. SOURCE: CDC/NCHS Matching algorithm Plurality State/County Mother’s DOB Date of Delivery Unmatched records Add LMP Allow 1 digit Difference in DOB or DOD Mother’s DOB Not Stated Add LMP 93% Matched 98.1% Matched

15. SOURCE: CDC/NCHS Comparison with Missouri 1995 matched multiple birth file  2,176 Missouri records reviewed  NO FALSE Matches  6 unmatched in NCHS but matched in Missouri file

16. SOURCE: CDC/NCHS Records matched by plurality 98.998.8

17. SOURCE: CDC/NCHS Records matched by outcome 98.899.0 87.5

18. SOURCE: CDC/NCHS X gestation35.4 32.4 (weeks) X birthweight2,342 1,962 (grams) % infant deaths 3.010.4 Differences in matched vs. unmatched records MatchedUnmatched

19. SOURCE: CDC/NCHS The NEW Matched Multiple Birth File Most data items on birth, fetal death Most data items on birth, fetal death and linked infant death records: and linked infant death records: Maternal age/Education Prenatal care Medical risk factors/Tobacco use Birthweight/Gestational age Cause of infant death Geographic detail Year of birth/death

20. SOURCE: CDC/NCHS Uses of the Matched Multiple Birth File Birthweight discordance Set gender SIDS Growth restriction Older moms Set order Parity

21. SOURCE: CDC/NCHS The NEW Matched Multiple Birth File JAMartin@cdc.gov BHamilton@cdc.gov MMunson@cdc.gov