Table 1.
Distribution of Study Variables in the Norway sample (N=507)
| Variable | Definition | Mean (SD) |
|---|---|---|
| Birth weight | Infant’s birth weight in grams | 3646.64 (589.76) |
| Smoking | Binary (0,1) indicator for smoking in the first trimester | 0.32 (0.47) |
| Daily smoking | Binary (0,1) indicator for daily smoking in the first trimester | 0.27 (0.44) |
| Cigarettes | Number of cigarettes per day smoked in the first trimester | 1.83 (3.79) |
| Binge drinking in the first trimestera | Binary (0,1) indicator for ≥ 4 drinks per drinking occasion in the first trimester | 0.05 (0.21) |
| Moderate drinking in the first trimester a | Binary (0,1) indicator for 2–3 drinks per occasion in the first trimester | 0.09 (0.29) |
| Low drinking in the first trimester a | Binary (0,1) indicator for 1 drink per occasion in the first trimester | 0.18 (0.39) |
| Binge drinking before pregnancy a | Binary (0,1) indicator for ≥ 4 drinks per drinking occasion in the last few years before pregnancy | 0.38 (0.49) |
| Moderate drinking before pregnancy a | Binary (0,1) indicator for having 2–3 drinks per occasion in the last few years before pregnancy | 0.4 (0.49) |
| Low drinking before pregnancy a | Binary (0,1) indicator for having 1 drink per occasion in the last few years before pregnancy | 0.13 (0.34) |
| Multivitamin use | Binary (0,1) indicator for using multivitamins before and during the first two months of pregnancy | 0.38 (0.49) |
| Underweightb | Binary (0,1) indicator for maternal BMI prior to pregnancy of less than 18.5 | 0.03 (0.17) |
| Overweightb | Binary (0,1) indicator for maternal BMI prior to pregnancy between 25 and 29.9 inclusive | 0.19 (0.39) |
| Obeseb | Binary (0,1) indicator for maternal BMI prior to pregnancy of greater than 29.9 | 0.07 (0.25) |
| Calories | Average daily calorie intake during the first trimester | 2281.19 (751.15) |
| Maternal age | Maternal age in years | 29.43 (4.7) |
| Married | Binary (0,1) indicator for married mothers | 0.53 (0.5) |
| Less than high schoolc | Binary (0,1) indicator for maternal education of less than completed high school | 0.09 (0.28) |
| High schoolc | Binary (0,1) indicator for maternal education of completed high school | 0.27 (0.44) |
| Technical collegec | Binary (0,1) indicator for mother attending technical college | 0.2 (0.4) |
| Universityc | Binary (0,1) indicator for mother completing university education | 0.07 (0.26) |
| Maternal employment | Binary (0,1) indicator for maternal employment in the first trimester | 0.86 (0.35) |
| Very low maternal incomed | Binary (0,1) indicator for current gross maternal yearly income of less than 150,000 kr | 0.34 (0.47) |
| Moderate maternal incomed | Binary (0,1) indicator for current gross maternal yearly income between 201,000 and 250,000 kr inclusive | 0.25 (0.43) |
| High maternal incomed | Binary (0,1) indicator for current gross maternal yearly income of 251,000 kr or more | 0.15 (0.35) |
| Pregnancy planning | Binary (0,1) indicator for mothers who were planning to become pregnant | 0.74 (0.44) |
| rs1041983_C/T | Binary (0,1) indicator of C/Tgenotype of rs1041983 | 0.43 (0.5) |
| rs1041983_C/C | Binary (0,1) indicator of C/Cgenotype of rs1041983 | 0.49 (0.5) |
| rs1930139_A/G | Binary (0,1) indicator of A/G genotype of rs1930139 | 0.32 (0.47) |
| rs1930139_G/G | Binary (0,1) indicator of G/G genotype of rs1930139 | 0.05 (0.21) |
| rs721398_C/T | Binary (0,1) indicator of C/T genotype ofrs721398 | 0.39 (0.49) |
| rs721398_C/C | Binary (0,1) indicator of C/C genotype of rs721398 | 0.07 (0.26) |
| rs5758589_A/G | Binary (0,1) indicator of AB genotype of rs5758589 | 0.49 (0.5) |
| rs5758589_G/G | Binary (0,1) indicator of BB genotype of rs5758589 | 0.25 (0.44) |
| rs1432007_A/G | Binary (0,1) indicator of AB genotype of rs1432007 | 0.52 (0.5) |
| rs1432007_G/G | Binary (0,1) indicator of BB genotype of rs1432007 | 0.26 (0.44) |
| rs2059574_A/T | Binary (0,1) indicator of A/T genotype of rs2059574 | 0.47 (0.5) |
| rs2059574_T/T | Binary (0,1) indicator of T/T genotype of rs2059574 | 0.34 (0.47) |
| rs2268973_A/G | Binary (0,1) indicator of A/G genotype of rs2268973 | 0.4 (0.49) |
| rs2268973_G/G | Binary (0,1) indicator of G/G genotype of rs2268973 | 0.52 (0.5) |
a
The reference category is no drinking;
b
The reference category is normal weight (18.5≤BMI<25);
c
The reference category is 2–4 years of college;
d
The reference category is 151,000–200,000 kr.