Table 1.

Studies investigating the effect of iodine supplementation in pregnancy.

Author (Year)	Country	n	Methods	Baseline UIC µg/L	Effect on child neurodevelopment
Romano et al. (1991) [21]	Italy	35	Women in first trimester randomised to 0 or iodine supplement (120–180 µg I/day).	37	Not assessed.
Pedersen et al. (1993) [22]	Denmark	54	Women at 17–18 weeks gestation randomised to 0 or 200 µg I/day.	55	Not assessed.
Glinoer et al. (1995) [23]	Belgium	120	Euthyroid women with signs of excessive thyroid stimulation randomised to 0 or 100 µg I/day.	36	Not assessed.
Liesenkotter et al. (1996) [20]	Germany	118	Women at 10–12 weeks gestation given 300 µg I/day vs. untreated women.	53	Not assessed.
Nohr and Laurberg (2000) [24]	Denmark	144	Retrospective allocation at term based on self-reported intake of supplements containing 150 µg I/day.	Not given	Not assessed.
Antonangeli et al. (2002) [25]	Italy	86	Healthy women 10–16 weeks gestation randomised to 50 or 200 µg I/day.	74	Not assessed.
Berbel et al. (2009) [26]	Spain	96	Women 4–6 weeks gestation with FT4 > 20th percentile (Group1) vs. women with FT4 < 10th percentile at 12–14 weeks (Group 2) or at 37–40 weeks (Group3) given 200 µg I/day until end of lactation.	75	Brunet-Lezine developmental quotient of children at 18 months was: 101.8 in Group 1 vs. 92.2 in Group 2 (p < 0.05) or 87.5 in Group 3 (p < 0.001).
Velasco et al. (2009) [27]	Spain	191	Women <10 weeks gestation (Group 1) vs. last month of pregnancy (Group 2) given 300 µg I/day until end of lactation.	87	Bayley Psychomotor Development Index of children was: 108.74 in Group 1 vs. 102.65 in Group 2 (p = 0.02).

UIC: urinary iodine concentration; TSH: Thyroid Stimulating Hormone; FT4: Free Thyroxine.