What role do thyroid hormones play in pregnancy?
Thyroid hormones are crucial for normal development of baby’s brain and nervous system. During the first trimester- the first 3 months of pregnancy the baby depends on mother’s supply of thyroid hormone, which comes through the placenta. NAt around 12 weeks, the baby’s thyroid starts to work on its own, but it doesn’t make enough thyroid hormone until 18 to 20 weeks of pregnancy.
Untreated hypothyroidism (underactive thyroid) in mother especially during the first 3 months of pregnancy can cause low IQ and problems with normal development. Normal levels of thyroid hormone are also essential also for brain development of newborn and are necessary for normal growth and pubertal development in children.
Why do women need more iodine during pregnancy?
In pregnancy the thyroid is very active, producing about 50% more thyroid hormones. Because thyroid uses iodine to make thyroid hormones, during pregnancy women need extra iodine to produce enough hormones to support the healthy development of the foetus.
Thyroid activity returns to normal when breastfeeding but an iodine supplement is recommended because breast fed infants get all of their iodine from breastmilk.
How much iodine do pregnant and breastfeeding women need?
Pregnant and breastfeeding women in Australia are not getting enough iodine through diet alone. A daily supplement that includes 150 micrograms of iodine is recommended for women when planning pregnancy, during pregnancy and while breastfeeding. There is no benefit to taking more than 150 micrograms of iodine.
Women with pre-existing thyroid conditions should talk to their doctor before taking a supplement.
When should women take iodine supplements?
Women should take iodine supplements when planning pregnancy, during pregnancy and while breastfeeding. If pregnancy is not planned, women should start taking an iodine supplement as soon as possible after finding out they are pregnant.
Key Messages for women planning a pregnancy
- Pregnant and breastfeeding women in Australia are not getting enough iodine through diet alone.
- A daily supplement that includes 150 micrograms of iodine is recommended for women when planning pregnancy, during pregnancy and while breastfeeding.
- Women with underactive thyroid or currently taking thyroid hormone replacement, and planning a pregnancy should see their doctor to monitor thyroid hormone levels when trying to get pregnant, throughout pregnancy and while breastfeeding. This will keep the mother and the baby safe, as ensuring thyroid hormone levels are adequate during this time is essential for the baby’s development.
- Women with Hashimoto’s thyroiditis with inadequate thyroid hormone levels, should get an evaluation by an Endocrinologist if planning a pregnancy or as soon as possible after finding out they are pregnant