Table 1 Distribution of maternal 1976 serum TCDD levels (ppt, lipid-adjusted) by maternal and child-based characteristics; SWHS, Italy, 1976–2016
|  | N (%) N = 676 children of 438 mothers | 1976 Serum TCDD (ppt) Median (IQR) |
|---|---|---|
Maternal characteristics (n = 438) | ||
 Age at explosion (years)* | ||
  < 11 | 137 (31.3) | 162.0 (57.8–327.0) |
  11–17 | 143 (32.7) | 55.0 (26.7–111.0) |
  18+ | 158 (36.1) | 43.8 (22.0–99.5) |
 Atopic history | ||
  Yes | 91 (20.8) | 85.2 (35.0–222.0) |
  No | 347 (79.2) | 63.3 (29.1–166.0) |
 Age at pregnancy (years) | ||
  < 26 | 140 (20.7) | 44.1 (21.0–103.5) |
  26–29 | 194 (28.7) | 62.3 (29.6–160.0) |
  30–33 | 177 (26.2) | 76.2 (34.4–214.0) |
  34+ | 165 (24.4) | 76.9 (37.5–214.0) |
 BMI (kg/m2) closest to birth year | ||
  < 25 (underweight/normal) | 477 (70.6) | 67.5 (30.8–185.0) |
  25–29 (overweight) | 148 (21.9) | 49.9 (23.7–164.0) |
  30+ (obese) | 51 (7.5) | 86.7 (28.4–162.0) |
 Smoking during pregnancy a | ||
  Yes | 63 (9.3) | 55.2 (20.7–109.0) |
  No | 609 (90.1) | 66.8 (30.2–185.0) |
Child Characteristics (n = 676) | ||
 Pre-term birth (< 37 weeks) | ||
  Yes | 46 (6.8) | 90.2 (33.2–245.0) |
  No | 630 (93.2) | 64.3 (29.6–173.0) |
 Season of birth | ||
  Spring | 174 (25.7) | 55.5 (29.0–196.0) |
  Summer | 167 (24.7) | 66.8 (29.9–174.0) |
  Fall | 171 (25.3) | 66.7 (28.6–176.0) |
  Winter | 164 (24.3) | 72.6 (33.4–170.0) |
 Breastfeeding duration (months) | ||
  < 1 | 214 (31.7) | 60.3 (28.6–150.0) |
  1–4 | 250 (37.0) | 69.9 (30.6–173.0) |
  5+ | 212 (31.4) | 66.2 (34.4–212.0) |
 Birth order | ||
  1 | 401 (59.3) | 70.0 (31.0–185.0) |
  2 | 236 (34.9) | 63.3 (29.3–172.0) |
  3+ | 39 (5.8) | 49.9 (19.5–105.0) |
 Sex | ||
  Males | 336 (49.7) | 60.1 (26.9–158.5) |
  Females | 340 (50.3) | 75.0 (33.2–196.0) |
 Age at follow-up* | ||
  2–13 | 161 (23.8) | 166.0 (49.0–433.0) |
  14–22 | 167 (24.7) | 66.2 (33.2–163.4) |
  23–30 | 171 (25.3) | 60.0 (29.4–123.0) |
  31–39 | 177 (26.2) | 40.7 (21.3–85.2) |
 Primary wage earner education at follow-up | ||
  Less than high school | 200 (29.6) | 65.3 (29.8–153.5) |
  High school | 251 (37.1) | 75.2 (33.3–247.0) |
  Greater than high school | 225 (33.3) | 60.0 (23.9–140.0) |