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Table 1 Characteristics of all mother-child dyads,those with at least one prenatal mercury and one BASC-2 behavior data, and dyads not included in the analyses due to missing either mercury or behavior assessment data [no. (%)]

From: Very low-level prenatal mercury exposure and behaviors in children: the HOME Study

Variable Women and singleton children (n = 389) Women and singleton children with at least one mercury and behavior measurement (n = 320) Dyads not included due to missing either mercury or behavior assessment data (n = 69)
Maternal age at delivery
  ≤ 30 years 207 (53.2) 162 (50.6) 45 (65.2)
  > 30 years 182 (46.8) 158 (49.4) 24 (34.8)
 Missing 0 0 0
Maternal ethnicity
 White 237 (61.7) 206 (64.4) 31 (48.4)
 Others 147 (38.3) 114 (35.6) 33 (51.6)
 Missing 5 0 5
Midpoint value of income category at baseline
  > $ 40,000 231 (60.2) 200 (62.5) 31 (48.4)
  ≤ $ 40,000 153 (39.8) 120 (37.5) 33 (51.6)
 Missing 5 0 5
Maternal education
 Completed Bachelor’s degree 191 (49.7) 170 (53.1) 21 (32.8)
 Not completed Bachelor’s degree 193 (50.3) 150 (46.9) 43 (67.2)
 Missing 5 0 5
Maternal marital status at baseline
 Married or living with partner 300 (78.1) 249 (77.8) 51 (79.7)
 Unmarried or living alone 84 (21.9) 71 (22.2) 13 (20.3)
 Missing 5 0 5
Child sex
 Male 181 (46.5) 145 (45.3) 36 (52.2)
 Female 208 (53.5) 175 (54.7) 33 (47.8)
 Missing 0 0 0
HOME score (at 12 months)
  ≥ 40 219 (65.6) 204 (67.6) 15 (46.9)
  < 40 115 (34.4) 98 (32.4) 17 (53.1)
 Missing 55 18 37
Maternal depression (BDI-II) at 20 weeks
 Minimal depression (≤13) 296 (77.7) 254 (80.1) 42 (65.6)
 Mild, moderate or severe depression (> 13) 85 (22.3) 63 (19.9) 22 (34.4)
 Missing 8 3 5
Fish intake
 Not at all 57 (14.9) 48 (15.0) 9 (14.1)
 Less than once a month 114 (29.8) 94 (29.5) 20 (31.2)
 1 to 3 times a month 132 (34.4) 108 (33.9) 24 (37.5)
 More than once a week 80 (20.9) 69 (21.6) 11 (17.2)
 Missing 6 1 5