Int. J. Environ. Res. Public Health 2010, 7 1904 When last menstrual period was missing, infants’ birth dates and a clinical estimate of gestation length were used. Since 1989, most states have required that mothers report drinking behaviors during pregnancy in the birth certificate. However, alcohol consumption is generally under-reported. Only around 2% of mothers reported that they drank during pregnancy in birth certificate data, versus the estimated 12% of pregnant women nationwide who actually did [26]. Therefore, mothers’ alcohol drinking in the Natality files was not employed in the estimation models. Instead, drinking behaviors (Equation (5)) were estimated based upon the Behavioral Risk Factor Surveillance System (BRFSS; 1985 to 2002), an ongoing nationally representative survey of the non-institutionalized US population age 18 years and older. Data in even years from 1994 to 2000 were dropped from the sample since only 10 states employed the alcohol module for those years. Only pregnant women were included in our sample and the survey year represented the conception year. Variable Birth weight Table 1. Variables definition and descriptive stats. Descriptive States A. Birth Outcomes (Natality Detailed Files, 1985–2002) * Birth weight in grams Low birth weight Indicator variable (1 if birth weight < 2,500 grams and 0 otherwise) Extremely low birth Indicator variable (1 if birth weight < 1,500 grams and 0 otherwise) weight Low APGAR scores Indicator variable (1 if APGAR score < 7 ) B. Drinking Behaviors (BRFSS, 1985–2002) ** Indicator variable (1 if a pregnant woman drank during the past 30 Drinker days) Average number of drinks during the past 30 days for pregnant Drinks / month women Indicator variable (1 if a pregnant women drank at least 5 drinks per Binge drinker occasion) C. Alcohol Taxes (1982–1984 US Dollars) *** Beer tax combined federal and state tax on beer per gallon in dollar Wine tax Liquor tax§ combined federal and state tax on wine per gallon in dollar combined federal and state tax on liquor per proof gallon in dollar Mean (sd) 3,329.7 (605.59) 0.07 (0.30) 0.01 (0.12) 0.01 (0.12) 0.127 (0.4545) 4 (20.34) 0.014 (0.1192) 0.6 (0.28) 1.02 (0.53) 15.78 (6.58) * There are 71,501,237 infants with birth weight and 55,054,916 with APGAR scores. ** Data from 1994, 1996, 1998 and 2002 were dropped because only 10 states employed the alcohol module in BRFSS for those years. *** In a state where alcoholic beverages, particularly distilled liquors, are sold through state stores, taxes combine specific, ad valorem and implicit taxes. Taxes are missing if it is a monopoly control state. § Taxes are much lower on the alcohol content of beer and wine than on the alcohol content of liquor or distilled spirits because the taxes are determined on the basis of different liquid measures. Liquor is measured in proof gallons (a standard unit for measuring the alcohol content of a liquid). Beer is measured by a barrel and wine is measured by a gallon.