Table 1

Association of maternal and infant factors with small for gestational age (SGA) offspring among National Birth Defects Prevention Study controls, 1997–2002

SGANot SGA
Characteristicn%n%p Value*
Total2212582
Age (years)
 <20104.52168.40.35
 20–246429.055121.3
 25–295826.270627.3
 30–344520.474728.9
 35+4419.936214.0
 Missing00
Race/ethnicity
 White non-Hispanic14163.8169065.50.14
 Black non-Hispanic198.633412.9
 Hispanic4721.344217.1
 Other146.31164.5
 Missing00
Education (years)
 <123114.02469.50.04
 125625.363724.7
 >1213460.6169765.8
 Missing02
Parity / number of previous live births
 08237.1114844.50.15
 19241.689534.6
 2+4721.353920.9
 Missing00
Infant sex
 Male12154.8128049.60.14
 Female10045.2130250.4
 Missing00
Cigarette smoking†
 Yes5826.252220.20.03
 No16373.8206079.8
 Missing00
Secondhand smoking at home†
 Yes5324.046317.90.03
 No16876.0211982.1
 Missing00
Secondhand smoking at work†
 Yes5223.551219.80.19
 No16976.5207080.2
 Missing00
Alcohol drinking†
 Yes10848.9120946.80.56
 No11351.1137353.2
 Missing00
Prepregnancy body mass index
 Underweight178.01265.00.01
 Normal weight13663.8143756.7
 Overweight3616.958823.2
 Obese2411.338515.2
 Missing846
Folate antagonist medication†
 Yes10.520.10.22‡
 No22099.5258099.9
 Missing00
Folic acid supplements†
 Yes20492.3243794.40.20
 No177.71455.6
 Missing00
Household income ($)
 <20 0006232.357325.30.47
 20 000–49 9996634.480535.6
 50 000+6433.388639.1
 Missing29318
Study centre
 Arkansas3214.532312.50.79
 California2310.430611.9
 Iowa2812.736414.1
 Massachusetts3214.537014.3
 New Jersey3415.434713.4
 New York229.929711.5
 Texas2913.126710.3
 CDC/Atlanta219.530811.9
 Missing00
  • *Probability calculated with χ2 test based on non-missing values.

  • †Maternal exposure during the period from 1 month before conception through delivery.

  • ‡Fisher's exact test.