Table 2 Characteristics and summary of findings of n = 12 studies included investigating associations between maternal urinary iodine assessment and child cognitive outcomes
Author | Country | Design | N | Gestational age at urine collection | Child age at testing | Cognitive tests | Urinary iodine assessment UIC and/or ICr | Association to cognitive outcomes | Quality |
|---|---|---|---|---|---|---|---|---|---|
Bath, S.C. et al., 2013 [6] | UK | Prospective cohort | 1040 mother child pairs | ~ 13 weeks gestation | 8–9 years | WISC; Neale Analysis of Reading Ability. | ICPMS: 91.1 μg/L UIC & ICr: 110 μg/g | Offspring of women with ICr < 150 μg/g had scores in lowest quartile (OR 1·58, 95% CI 1·09–2·30; p = 0·02), reading accuracy (1·69, 1·15–2·49; p = 0·007), and reading comprehension (1·54, 1·06–2·23; p = 0·02) | 9 |
Markhus, M.W. et al., 2018 [20] | Norway | Prospective cohort | 851 mother child pairs | 23.7 weeks | 6.1, 12.2 and 18.4 months | BSID-III | ICPMS: 78 μg/L n = 155 women reported supplement use with UIC higher 92 μg/L | UIC < 100 μg/L associated with poorer receptive (p = 0.025) and expressive language skills (p = 0.002). Iodine-containing supplements was associated with lower gross motor skills (b = −0.18, 95% CI = − 0.33, − 0.03, p = 0.02), | 9 |
Van Mil, N.H. et al., 2012 [21] | The Netherlands | Prospective cohort | 1156 mothers and 692 children | 13.2 weeks | 4 | BRIEF-P | Ammonium persulfate: 203 μg/g ICr (median) Supplement use in 27.1% of women with urinary iodine <10th percentile and 30.8% >10th percentile | Offspring of women with low urinary iodine scores had higher scores on the problem scales of inhibition [b = 0.05 (95% CI: 0.01, 0.10), P = 0.03] and working memory [b = 0.07 (95% CI: 0.02, 0.12), P = 0.003]. | 9 |
Hynes, K.L. et al., 2013 [19] | Australia | Longitudinal follow up | 433 mothers and 228 offspring | Mean 24.6 weeks (8–41 weeks range) | 9 | NAPLAN and SARIS tests | Kolthoff method: Median UIC 81 μg/L 71.1% mothers had UIC < 150 μg/L 29.9% mothers had UIC > 150 μg/L | Maternal UIC < 150 μg/L had offspring with 10% reductions in spelling (95% CL 68.0 to 14.3; p = 0.003), 7.6% in grammar (95% CI 60.2 to 1.7, P = 0.038), and 5.7% in English-literacy (95% CI, 0.63 to 0.03; P = 0.034) performance compared to maternal UIC > 150 μg/L. | 9 |
Hynes, K.L. et al., 2017 [18] | Australia | Longitudinal follow up | 449 mothers and 266 offspring | Mean 23.7 weeks (6–41 weeks) | 13–14 years | NAPLAN tests | Kolthoff method: Median UIC 83.2 μg/L | Maternal UIC < 150 μg/L had offspring exhibiting persistent reductions in spelling from Year 3 (95% CL −65.1 to −17.6; p = 0.001)) to Year 9 (95% CL − 57.0 to − 6.2, p = 0.015)) compared to maternal UIC ≥ 150 μg/L. | 8 |
Abel, M.H. et al., 2017 [22] | Norway | Prospective cohort | 53′360 mother-child pairs (19′086 for ADHD score) | 18 (n = 1950 for UIC measurements) | 9.9 (median) | ADHD Rating Scale | ICPMS: Median UIC 61 μg/L (n = 1950 for non-supplement users); 86 μg/L (n = 988 for supplement users) | NS | 9 |
Abel, M.H., et al., 2018 [23] | Norway | Prospective cohort | 39,471 mother child pairs | 0–22 (wk. 18 for UIC, n = 2001) | 8 | CCCS; Vineland Adaptive Behaviour Scale; Performance tests for reading, writing and maths. | ICPMS: Median UIC 67 μg/L; 95 μg/L in supplement users and 59 μg/L in non-supplement users. | NS | 9 |
Murcia, M. et al., 2017 [24] | Spain | Prospective cohort | 2644 women recruited and 1803 children | 13.5 | 4.8 | MSCA | Paired-ion reversed-phase HPLC: 123 μg/L UIC (median) and ICr 151 μg/g | NS | 9 |
Zhou, S.J. et al., 2018 [25] | Australia | Prospective cohort | 699 mother child pairs | < 20 and 28 | 19.5 months | BSID-III | Sandell-Kolthoff UIC 186 μg/L | NS | 9 |
Cromie, K.J. et al., 2020 [26] | UK | Prospective cohort | 6955 mothers | 26–28 weeks | 8–12 years | ASD Diagnosis through CTV3 read code | ICPMS: Median (inter-quartile range) UIC was 76 μg/L (46, 120) and ICr was 83 μg/g (59, 121) | NS | 9 |
Ghassabian, A. et al., 2014 [27] | The Netherlands | Prospective cohort | 1525 mother-child pairs | < 18 weeks gestation | 6 years | Non-verbal IQ and language comprehension | Ceri-arsenite reaction: median UIC creatinine = 229.6 μg/g (whole sample) < 150 μg/g median was 119.3 μg/g (12.3%) and > 150 μg/g was 322.9 μg/g | NS | 9 |
Threapleton, D.E. et al., 2020 [28] | UK | Prospective cohort | 6971 mothers5745 children | 26–28 weeks gestation | 4–7 years | EYFS, phonics, and KS1 learning outcomes/social/behavioural difficulties, and sensorimotor control | Jaffe reaction: Median (interquartile range) UIC was 76 μg/L (46, 120), and ICr was 83 μg/g (59, 121). | NS | 9 |