Low maternal iodine intake and early pregnancy hypothyroxinemia: Possible repercussions for children

Area of Science:

• Endocrinology
• Maternal-Fetal Medicine
• Nutritional Science

Background:

• Early pregnancy hypothyroxinemia (low free thyroxine [FT4] with normal thyroid-stimulating hormone [TSH]) is associated with adverse neurodevelopmental outcomes in children.
• Iodine deficiency is a global health concern, particularly impacting pregnant women and fetal development.

Purpose of the Study:

• To determine the incidence of early pregnancy hypothyroxinemia in pregnant women in Pakistan.
• To investigate the association between iodine intake and thyroid hormone levels in pregnant women.

Main Methods:

• A cross-sectional study involving 254 pregnant women in their first trimester.
• Measurement of urinary iodine (UI) and serum thyroid hormones (FT4, FT3, TSH).
• Categorization of participants into iodine deficient (ID; UI <100 μg/L) and iodine sufficient (IS; UI ≥ 100 μg/L) groups.

Main Results:

• A high prevalence of iodine deficiency (79.5%) was observed.
• Maternal FT4 levels significantly correlated with UI (r=0.36; P<0.001), with IS women showing higher FT4 than ID women.
• Hypothyroxinemia (FT4 <10.2 pmol/L, TSH <2.5 mIU/L) was diagnosed in 11.8% of pregnant women, predominantly in the iodine-deficient group (OR=8.5).

Conclusions:

• Approximately 12% of urban Pakistani pregnant women exhibit hypothyroxinemia, primarily due to insufficient iodine intake.
• Low iodine intake during pregnancy is a significant risk factor for developing hypothyroxinemia.
• Findings underscore the importance of adequate iodine nutrition for optimal maternal and fetal health.