Iodine is a mineral found in food — and one of the most important nutrients that a fetus needs for brain development and physical growth. While our bodies require only the teeny-tiniest amount of it (just 5 grams over the course of a 70-year lifetime!), that little bit of iodine in our diet is really important. It maintains normal function of the thyroid, a gland in the base of your neck. The thyroid regulates the hormones controlling your metabolism, heart rate, body temperature and other core body functions.

Getting enough iodine ensures that your baby develops a healthy and normal thyroid too. In rare cases where a fetus has an underdeveloped thyroid, it can lead to negative effects like low IQ, developmental delays, deafness, impaired physical and developmental growth, and other problems.

Iodine is also key in lactation, since you pass iodine on to your baby through your breast milk. That means the iodine you consume during pregnancy continues to support your baby's brain and thyroid development until she stops breastfeeding and fully transitions to solids.
A lack of the trace element Iodine is called Iodine Deficiency. Iodine deficiency disorders (IDD) include:

• Goiter
• Mental retardation
• Hypothyroidism
• Cretinism
• Increased morbidity and mortality of infants
• Impaired cognitive development

Through the Republic Act No. 8172, “An Act for Salt Iodization Nationwide” which was enacted in 1995, seeks to contribute to the elimination of micronutrient malnutrition in the country, particularly iodine deficiency disorders, through the cost-effective preventive measure of salt iodization, the country’s initiatives in combating Iodine Deficiency were salt iodization, use of iodized salt in processed foods, and Iodization of drinking water.

Credits and Source:
Iodine in Pregnancy — Why It’s Important, Foods to Eat (whattoexpect.com)
http://enutrition.fnri.dost.gov.ph/site/uploads/2018%20ENNS%20Dissemination_Salt.pdf