The findings of a pilot, randomized, double-blind trial revealed that in a group of pregnant females with mild iodine deficiency, an everyday supplement with 150 μg of iodine led to improvement in the iodine status. Researchers explored the influence of iodine supplementation on iodine and thyroid status in 200 thyroid-healthy pregnant females.

Participants were enrolled at a mean (standard deviation) pregnancy week 8.85 (1.62) and allocated to an everyday consumption of a multivitamin tablet without or with iodine. Collection of urine and serum samples was done at baseline and once during the 2nd and 3rd trimesters. Analysis of serum thyroglobulin, urinary iodine concentration, thyroid-stimulating hormone, thyroid peroxidase antibodies, and free thyroxine was done.

Collection of neonatal thyroid-stimulating hormone data was done. Analysis of urinary iodine concentration and thyroglobulin was also done in a cohort of 89 thyroid-healthy non-pregnant females of reproductive age. Both intervention and control arms showed a comparable median urinary iodine concentration (interquartile range [IQR]): 110 μg/L (74-119) and 111 μg/L (66-168), respectively at the baseline. The intervention arm attained iodine sufficiency with median urinary iodine concentration (IQR) 136 μg/L (91-211) and 139 μg/L (89-234) in the 3rd and 2nd trimester, respectively. No considerable difference was noted from lower limit of suggested range, i.e. 150-250 μg/L.

The intervention group exhibited an increased median urinary iodine concentration and reduced median thyroglobulin compared to the control group during the 2nd and 3rd trimesters. On the other hand, the neonatal thyroid-stimulating hormone, thyroid hormones, and serum thyroid peroxidase antibodies were comparable. The women of the reproductive age group exhibited a median urinary iodine concentration (IQR) of 65 μg/L (30-98) and median thyroglobulin (IQR) of 18 μg/L (13-27).

Regular iodine supplementation improves the maternal iodine status, and this improvement appears to exhibit a favorable influence on the maternal thyroid metabolism, as demonstrated by serum thyroglobulin. However, it did not impact maternal thyroid morbidity.