Table 1.
Population Characteristics
| Generation R (n = 1931) | INMA (n = 1269) | ALSPAC (n = 2980) | ||||
|---|---|---|---|---|---|---|
| n | Values | n | Values | n | Values | |
| Offspring neurodevelopment, no. (%) | ||||||
| Suboptimal nonverbal IQa | 1540 | 175 (11.4) | 1269 | 216 (17.0) | 2979 | 479 (16.1) |
| Suboptimal verbal IQa | 1618 | 279 (17.2) | 1269 | 211 (16.6) | 2977 | 480 (16.1) |
| Female sex, no. (%) | 1931 | 963 (49.9) | 1268 | 632 (49.8) | 2980 | 1514 (50.8) |
| Iodine status | 1931 | 1269 | 2980 | |||
| UI/Creat, µg/g, median (IQR) | 214 (143–308) | 152 (96–258) | 124 (82–199) | |||
| UI/Creat <150 µg/g, no. (%) | 531 (27.5) | 623 (49.1) | 1831 (61.4) | |||
| UI/Creat >500 µg/g, no. (%) | 97 (5.0) | 52 (4.1) | 81 (2.7) | |||
| UIC, µg/L, median (IQR) | 159 (90–275) | 128 (75–213) | 96 (57–153) | |||
| Gestational age at urine sampling, wk | 1931 | 1267 | 2980 | |||
| Median (IQR) | 13.1 (12.1–14.8) | 13.0 (12.4–14.1) | 12.0 (8.0–16.0) | |||
| Range (min–max) | 6.1–30.5 | 8.6–39.4 | 1.0–42.0 | |||
| >20th week of gestation, no. (%) | 66 (3.4) | 130 (10.2) | 211 (7.1) | |||
| Maternal thyroid function | ||||||
| TSH, mIU/L, median (IQR) | 1719 | 1.29 (0.79–1.95) | 1227 | 1.25 (0.85–1.80) | 1102 | 0.97 (0.64–1.38) |
| FT4, pmol/L, median (IQR) | 1728 | 14.6 (12.9–16.5) | 1229 | 10.6 (9.7–11.6) | 1108 | 16.2 (14.9–17.7) |
| TPOAb positivity, no. (%) | 1737 | 98 (5.6) | NA | NA | 1111 | 146 (13.1) |
| Gestational age, wk, mean (SD) | 1733 | 13.3 (1.9) | 1228 | 13.2 (1.4) | 1118 | 10.3 (2.7) |
| Educational level, no. (%) | 1835 | 1265 | 2888 | |||
| Low | 154 (8.4) | 270 (21.3) | 573 (19.8) | |||
| Middle | 760 (41.4) | 525 (41.5) | 1810 (62.7) | |||
| High | 921 (50.2) | 470 (37.2) | 505 (17.5) | |||
| Maternal ethnicity/country of birth, no. (%) | 1803 | 1266 | 2877 | |||
| Spanish | NA | 1184 (93.5) | NA | |||
| Latin-American | NA | 56 (4.4) | NA | |||
| European/other | NA | 26 (2.1) | NA | |||
| Dutch | 1012 (53.2) | NA | NA | |||
| Indonesian | 69 (3.6) | NA | NA | |||
| Cape Verdean | 58 (3.1) | NA | NA | |||
| Moroccan | 115 (6.0) | NA | NA | |||
| Surinamese | 154 (8.1) | NA | NA | |||
| Turkish | 170 (9.0) | NA | NA | |||
| Other, non-Western | 150 (7.9) | NA | NA | |||
| Other, Western | 174 (9.1) | NA | NA | |||
| White | NA | NA | 2841 (98.7) | |||
| Nonwhite | NA | NA | 36 (1.3) | |||
| Maternal age, y, mean (SD) | 1931 | 30.5 (4.8) | 1257 | 31.6 (3.9) | 2980 | 28.6 (4.5) |
| Parity, no. (%) | 1931 | 1267 | 2877 | |||
| 0 | 1121 (58.1) | 727 (57.4) | 1346 (46.8) | |||
| 1 | 564 (29.2) | 458 (36.1) | 992 (34.5) | |||
| ≥2 | 246 (12.7) | 82 (6.5) | 539 (18.7) | |||
| Smoking during pregnancy, no. (%) | 1744 | 1254 | 2926 | |||
| Never | 1319 (75.6) | 870 (69.4) | 2434 (83.2) | |||
| In the beginning of pregnancy | 168 (9.6) | 168 (13.4) | 125 (4.3) | |||
| Continued | 257 (14.7) | 216 (17.2) | 367 (12.5) | |||
| Prepregnancy BMI, kg/m2, median (IQR) | 1694 | 22.6 (20.8–25.2) | 1269 | 22.5 (20.8–25.0) | 2713 | 22.2 (20.5–24.4) |
Values are based on unimputed data.
Abbreviations: BMI, body mass index; IQR, interquartile range; NA, not applicable.
a
Suboptimal is defined as an IQ score <85.