Baseline characteristics (n=1525)
| UIC adjusted for creatinine levels | |||
|---|---|---|---|
| >150 μg/g | <150 μg/g | p Value | |
| Maternal characteristics | |||
| Age at enrolment, years | 30.8 (4.6) | 28.6 (5.3) | <0.001 |
| Body mass index at enrolment | 24.4 (4.3) | 25.3 (5.1) | 0.01 |
| Education, % | |||
| Primary | 18.2 | 27.5 | 0.01 |
| Secondary | 54.3 | 52.2 | |
| Higher education | 27.5 | 20.3 | |
| Psychopathology score in pregnancy | 0.14 (0.00–1.02) | 0.21 (0.02–1.31) | <0.001 |
| Smoking, % | |||
| Never | 78.6 | 73.1 | 0.24 |
| Stopped when pregnant | 8.5 | 10.8 | |
| Continued in pregnancy | 12.9 | 16.1 | |
| Household income | |||
| <€1200 | 6.7 | 11.5 | 0.10 |
| >€1200 and <€2000 | 14.3 | 13.4 | |
| >€2000 | 79.0 | 75.1 | |
| Marital status, married/with partner % | 90.4 | 78.9 | <0.001 |
| Folate concentration in early pregnancy, nmol/L | 19.2 (9.2) | 17.2 (8.2) | 0.004 |
| Free thyroxine in early pregnancy, pmol/L | 15.28 (0.22) | 14.94 (0.09) | 0.15 |
| Thyroid stimulating hormone in early pregnancy, mU/L | 1.44 (0.08) | 1.56 (0.04) | 0.20 |
| Maternal IQ score | 97 (79–113) | 97 (80–113) | 0.14 |
| UIC adjusted for creatinine | 322.9 (168.6–732.2) | 119.3 (65.5–147.1) | <0.001 |
| Gestational age at urine sampling | 13.1 (10.5–16.8) | 12.9 (10.2–16.5) | 0.55 |
| Paternal characteristics | |||
| Age at enrolment, years | 33.5 (5.8) | 31.9 (6.2) | <0.001 |
| Education, % | |||
| Primary | 16.6 | 19.8 | 0.23 |
| Secondary | 46.6 | 51.3 | |
| High | 36.8 | 28.9 | |
| Child characteristics | |||
| Age at visit, years | 5.9 (0.2) | 5.9 (0.2) | 1.00 |
| Sex, boy % | 48.8 | 49.5 | 0.87 |
| First born % | 59.1 | 62.0 | 0.44 |
| Ethnic background % | |||
| Dutch | 57.5 | 57.2 | 0.67 |
| Other Western | 8.7 | 7.0 | |
| Non-Western | 33.8 | 35.8 | |
| Birth weight | 3441 (521) | 3419 (493) | 0.60 |
| Gestational age at birth | 40.3 (37.4–42.1) | 40.3 (37.2–41.9) | 0.90 |
| Breast feeding at 6 months, yes | 35.6 | 26.7 | 0.03 |
| IQ scores at 6 years | 102 (15) | 100 (16) | 0.12 |
| Language comprehension score at 6 years | 0.85 (0.62–0.96) | 0.85 (0.61–0.96) | 0.87 |
Numbers are mean (SD) for variables with normal distribution, median (90% range) for not normally distributed variables and percentages for categorical variables.
UIC, urinary iodine concentration.