Table 1 Characteristics of the mother, delivery and pregnancy, and early-life environment (n = 168 mothers)
| Â | Total | Â | Type of twin | Â | Â |
|---|---|---|---|---|---|
|  | n/N |  | MZMC n = 53 (31.5%) | MZDC n = 54 (32.1%) | DZ n = 61 (36.3%) |
Maternal, pregnancy and delivery characteristics | Â | Â | Â | Â | Â |
 Maternal age (years), median (p25-p75) | 163/168 | 27.0 (24.0–30.0) | 26.0 (24.0–30.0) | 27.0 (25.0–29.0) | 28.0 (24.8–31.0) |
 Parity (primi), n (%) | 167/168 | 78 (46.7%) | 24 (45.3%) | 26 (48.1%) | 28 (46.7%) |
 Maternal weight before pregnancy (kg), median (p25-p75) | 151/168 | 58.0 (53.5–63.0) | 58.0 (54.5–62.3) | 56.0 (52.0–60.3) | 60.0 (53.3–67.0) |
 Maternal weight gain during pregnancy (kg), median (p25-p75) | 135/168 | 13.0 (10.0–17.0) | 13.2 (11.1–15.0) | 13.0 (10.0–17.3) | 12.0 (10.0–17.0) |
 Maternal height (cm), mean + SD | 150/168 | 164 + 6.3 | 165 + 6.0 | 163 + 6.3 | 165 + 6.4 |
 Gestational age (weeks), median (p25-p75) | 166/168 | 38 (36.0–39.0) | 37.0 (36.0–38.0) | 38.0 (36.0–39.0) | 38.0 (36.0–39.0) |
 Delivery mode (c-section), n (%) | 141/168 | 17 (12.1%) | 2 (4.7%)* | 8 (17.0%)* | 7 (13.7%)* |
 Maternal education, n (%) | 153/168 |  |  |  |  |
  No education or primary education |  | 25 (16.3%) | 12 (25.5%)* | 4 (8.3%)* | 9 (15.5%)* |
  Lower secondary education |  | 31 (20.3%) | 6 (12.8%)* | 12 (25.0%)* | 13 (22.4%)* |
  Higher secondary education and tertiary education |  | 97 (63.4%) | 29 (61.7%)* | 32 (66.7%)* | 36 (62.1%)* |
 Smoking during pregnancy, n (%) | 156/168 | 21 (86.5%) | 5 (10.2%) | 7 (14.3%) | 9 (15.5%) |
Environmental exposures and neighborhood characteristics during pregnancy and early life | Â | Â | |||
 Neighborhood household income (euro), median (p25-p75) | 168/168 | 1800 (1646–2127) | 1738 (1698–1926) | 1863 (1641–2178) | 1800 (1634–2201) |
  Low-income household |  | 41 (24.4%) | 11 (20.8%) | 14 (25.9%) | 16 (26.2%) |
  Middle-income household |  | 85 (50.6%) | 32 (60.4%) | 24 (44.4%) | 29 (47.5%) |
  High-income household |  | 42 (25%) | 10 (18.9%) | 16 (29.6%) | 16 (26.2%) |
 Distance from residence to nearest major road (m), median (p25-p75) | 168/168 | 276 (110–618) | 276 (124–617) | 271 (120–632) | 321 (95–552) |
 Distance from residence to nearest highway (m), median (p25-p75) | 168/168 | 3627 (2071–7670) | 4399 (2124–7542) | 5203 (2398–10,324) | 3125 (2017–5401) |
 Green spaces within a 5000 m buffer from the home address (%), median (p25-p75) | 168/168 | 3.9 (2.9–5.6) | 4.1 (2.8–5.5) | 4.4 (3.1–6.4) | 3.8 (3.0–4.9) |