Can Mild to Moderate Iodine Insufficiency During Pregnancy Alter Thyroid Function? Lessons from Mother-newborn Matching Pairs Cohort
2Foreign studies, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem
3Endocrine Institute, Shamir Medical Center
4Sackler Faculty of Medicine, Tel Aviv University
5School of Nutritional Science. Institute of Biochemistry, Food Science and Nutrition, Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University of Jerusalem
6Department of Neonatology, Barzilai University Medical Center
7Faculty of Health Sciences, Ben-Gurion University of Negev
8Women's Health Center, Maccabi Healthcare Services, Southern Region
9National Newborn Screening Program, Ministry of Health
10National Public Health Laboratory, Ministry of Health
Background:
Severe iodine deficiency (ID) during pregnancy has substantial hormonal consequences, such as irreversible fetal brain damage. However, data on the potential effects of mild-to-moderate (ID) on thyroid function of pregnant women and their newborns are
scarce and divergent.
Objective:
We investigated the association between iodine status in pregnancy and both maternal and neonatal thyroid function in a region with mild-to-moderate ID.
Methods:
A single-center study, including rigorious observation during pregnancy and birth. Pregnant women’s iodine status was evaluated by an iodine food frequency questionnaire, serum thyroglobulin (Tg), urinary iodine concentration (UIC). Neonatal thyrotropin (nTSH) values were measured after birth. Obstetrics and anthropometric data were also collected.
Results:
Among the 178 women (median age 31 years) included in the study, median (interquartile range) estimated dietary iodine intake, Tg and UIC were 179 (94-268) μg/d, 18 (11-33) μg/L, and 60 (41-95) μg/L, respectively. There was a significant inverse association of iodine intake with Tg values among the study population (β=−0.2, F=7.5, p<0.01). Women with high free triiodothyronine (FT3) values were significantly more likely to exhibit an estimated iodine intake below the estimated average requirement (160 μg/d, odds ratio [OR]=2.6; 95% confidence interval [CI], 1.1-6.4; p=0.04), less likely to consume iodine-containing supplements (OR=0.3, 95% CI, 0.1-0.8; p=0.01), and deliver a greater proportion of newborns with nTSH ≥20 IU/L (p=0.04).
Conclusions:
Iodine insufficiency during pregnancy in regions with mild ID may be associated with altered maternal thyroid function. The relatively small sample size of the studied population and the possible association with congenital hypthyroidism warrants further investigation.
