Urinary iodine excretion and maternal thyroid function. During pregnancy and postpartum.

Area of Science:

• Endocrinology
• Reproductive Medicine
• Nutritional Science

Background:

• Pregnancy significantly alters maternal thyroid hormone levels and iodine metabolism.
• Understanding these changes is crucial for maternal and fetal well-being.
• Iodine deficiency can have profound effects on thyroid function during gestation.

Purpose of the Study:

• To assess urinary iodine excretion and maternal/neonatal thyroid function in Saudi pregnant women.
• To investigate the relationship between iodine status and thyroid parameters throughout pregnancy and postpartum.
• To identify potential iodine deficiency in pregnant women in Jeddah, Saudi Arabia.

Main Methods:

• Prospective longitudinal study of 80 Saudi pregnant women and 65 postpartum women.
• Measurement of maternal urinary iodine excretion and serum thyroid function tests (T4, T3, TSH, rT3, TBG, Tg).
• Comparison with 200 non-pregnant women; neonatal thyroid function also assessed.

Main Results:

• Subclinical iodine deficiency observed in 28.8% of pregnant women at term and 11.5% postpartum.
• Significant alterations in thyroid hormone levels (decreased free T4/T3, increased rT3) and thyrotropin (TSH) during pregnancy.
• Negative correlation between maternal free thyroxine (FT4) and neonatal TSH; positive correlation between neonatal T4 and birth weight/maternal iodine.

Conclusions:

• Pregnancy-induced thyroid hormone changes resemble non-thyroidal illness, suggesting complex regulatory mechanisms.
• Maternal thyroid activity appears influenced by both pituitary and chorionic systems, potentially for energy conservation.
• Increased iodine supply is recommended for Saudi pregnant women in Jeddah to prevent adverse effects of low iodine intake.