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Table 2 Characteristics of the study population from Four Memorial Care Hospitals in Southern California

From: Comparison of birth certificates and hospital-based birth data on pregnancy complications in Los Angeles and Orange County, California

  Matched memorial care data Unmatched Memorial Care data p-value* Matched birth certificate data Unmatched birth certificate data p-value**
  Valid matching variables Missing matching variables    Valid matching variablesa  
N 62200 4162 6138   62200 9312  
Rate of preeclampsia (2001–2006 data) 3.13 3.73 4.12 <0.01 1.38 1.97 <0.01
Rate of preeclampsia (2001–2005 data) 3.12 3.70 4.12 <0.01 1.34 1.75 <0.01
Rate of preeclampsia (2006 data only) 3.13 3.90 N.A. 0.41 1.57 2.23 <0.01
Rate of total diabetes (2001–2005 data) 5.56 6.65 5.46 0.17 1.97 2.11 0.40
Rate of total diabetes (2006 data only) 6.93 7.20 N.A. 0.35 2.24 3.67 <0.01
Rate of gestational diabetes (2006 data only) N.A. N.A. N.A.   1.62 2.57 0.01
Rate of chronic diabetes (2006 data only) N.A. N.A. N.A.   0.62 1.10 0.04
Maternal ageb (%)     <0.01    <0.01
  <20 6.62 5.77 N.A.   6.62 5.76  
 20–29 42.38 39.60 N.A.   42.44 39.79  
 30–39 46.75 47.57 N.A.   46.77 48.41  
 40+ 4.18 6.78 N.A.   4.16 6.04  
 Unknown 0.07 0.29 N.A.   0.00 0.00  
Maternal ageb (years): mean ± standard deviation 29.79 ± 6.17 30.56 ± 6.46 N.A. <0.01 29.78 ± 6.16 30.44 ± 6.34 <0.01
Maternal education (%)        <0.01
 College or higher N.A. N.A. N.A.   57.26 52.71  
 High school or lower N.A. N.A. N.A.   40.82 43.93  
 Unknown N.A. N.A. N.A.   1.92 3.36  
Race/ethnicityb (%)     <0.01    <0.01
 Asian 10.49 9.61 N.A.   13.65 14.85  
 Black 8.47 6.68 N.A.   8.96 6.20  
 Hispanic 33.01 42.74 N.A.   36.97 39.42  
 Non-Hispanic White 39.62 30.56 N.A.   37.62 35.72  
 Other 4.52 5.00 N.A.   1.91 1.98  
 Unknown 3.88 5.41 N.A.   0.89 1.84  
Insuranceb (%)     <0.01    <0.01
 Private 65.95 57.81 N.A.   66.77 66.91  
 Public 29.97 35.66 N.A.   32.69 32.25  
 Other 0.00 0.00 N.A.   0.44 0.63  
 Unknown 4.07 6.54 N.A.   0.11 0.20  
  1. * p-value for the comparison between the matched Memorial Care and the unmatched Memorial Care data with valid matching variables
  2. ** p-value for the comparison between the matched birth certificate data and the unmatched birth certificate data (all had valid matching variables)
  3. aAll records in the unmatched birth certificate data had valid matching variables
  4. bBoth databases have reported values for these variables. In this table, we calculated the statistic summaries based on the values reported in each specific database