Cheryl R. Stein, PhD, and David A. Savitz, PhD

Mount Sinai School of Medicine

To examine the independent and joint effects of maternal race/ethnicity and body mass index (BMI) on the association between gestational weight gain (GWG) and birth outcome, New York City vital statistics birth data for 1995 to 2003 was linked to hospital discharge data from the Statewide Planning and Research Cooperative System (SPARCS). Of 1,173,053 birth records, 1,084,882 (92.5 percent) were successfully matched to a hospital discharge record. Unmatched records resulted from missing personal information needed for the matching algorithm. Singleton births were more likely to be matched to a hospital discharge record than infants from a multiple gestation. Of 1,133,020 vital records for singleton births, 1,067,356 (94.2 percent) were successfully linked to a hospital discharge record (see Tables G-39 and G-40).

Of the 1,067,356 singleton births with matched vital records and hospital discharge data, 913,461 (85.6 percent) were potentially eligible for analysis. Inclusion criteria, and the corresponding percent lost, are GWG between −10 to 40 kg (10.7 percent), no birth defects (2.2 percent), non-missing outcome and covariate (maternal age, race/ethnicity, parity, education, smoking) data (1.2 percent), gestational age between 26 and 42 completed weeks (1.0 percent), and plausible combination of birth weight and gestational age (0.7 percent) (Alexander et al., 1996). Maternal height, needed to calculate BMI, was reported for births to New York City residents in hospitals located elsewhere in New York State, which were only 34,307 (3.8 percent) of these 913,461 potentially eligible births. As indicated in Table G-41, women with height reported had higher pre-pregnancy and delivery weights, more frequent primary cesarean sections, fewer term small-for-gestational age (SGA) and more term large-for-gestational age (LGA) births. Additionally, these women were more often from Queens and the Bronx, which likely accounts for the increased proportion of white non-Hispanic women.