Low iodine intake during pregnancy: relationship to placental development and head circumference in newborn.

Introduction: Iodine is considered to be an essential micronutrient in pregnant women. Iodine placental transport to the embryo---fetus is essential for hormone synthesis and is crucial for nervous system development. However, the relationship between iodine intake and placental weight and its potential implications for the newborn have not been studied. Material and methods: Iodine intake was analyzed in 77 pregnant women based on urinary iodine excretion (UIE) levels, measured using Pino’s modified method (normal value, ≥150 g/L). Placental weight was measured (PW: normal, ≥500 g). In the newborn, weight, height, and head perimeter (HP) were also measured. Placental index (PI: placental weight/newborn weight) was calculated, and was considered normal if ≥0.15. Results: UIE was normal in 50 pregnant women (mean ± SD, 279 ± 70.22 g/L) and decreased in 27 (94 ± 31.49 g/L). Newborns of mothers with low UIE had a similar weight (3357 ± 416.30 g; n: 27) to those of mothers with normal UIE (3489 ± 560.59 g; n: 50). Forty-four percent of mothers with low UIE had PW <500 g, and statistically lower HPs were found in newborns of mothers with low PW (PW 3 500 g: 36.05 ± 0.55 cm, n: 54; PW < 500 g: 33.93 ± 15 cm, n: 23, p < 0.019). Similar results were found with PI, but they did not reach statistical significance (0.17 ± 0.04; p = 0.066). No differences were seen in all other parameters. Conclusion: The study suggests the existence of a relationship between PW and HP. This finding may be related to iodine intake during pregnancy.