# Iodine in the third trimester

Source: https://www.pregnancypowerhour.com/nutrition/iodine-trimester-3
Last updated: 2026-07-01

> In the third trimester, consistent iodine intake remains vital for your baby's continued brain development and to support your body's sustained metabolic needs through late pregnancy and into breastfeeding.

As you navigate the final months of pregnancy, the demand for iodine remains significant, playing a critical role in your baby's ongoing neurological development and supporting your own thyroid function. While often discussed in early pregnancy, iodine's importance doesn't diminish in the third trimester; rather, it's about sustaining adequate levels for both you and your baby's maturation. Evidence suggests that mild iodine deficiency is widespread globally, including in pregnant populations in the US and UK. The World Health Organization (WHO) highlights iodine deficiency in pregnancy as the leading preventable cause of intellectual disability worldwide, underscoring why consistent attention to this mineral is so important throughout your entire pregnancy.

Meeting your iodine needs primarily through food is a gentle, effective approach. Key sources include iodized salt, dairy products, various types of seafood, and seaweed. It's worth noting that many common salts, like sea salt and kosher salt, are typically not iodized, so checking labels can be helpful if you rely on salt for iodine intake. While we often focus on minerals like [Calcium in the third trimester](/nutrition/calcium-trimester-3) for bone development, or [Iron in the third trimester](/nutrition/iron-trimester-3) for blood volume, iodine's contribution to cognitive development is equally foundational, ensuring a broad spectrum of support for your growing baby.

For many, a prenatal vitamin can help bridge any dietary gaps. Many prenatal vitamins contain around 150 mcg of iodine, which can be a helpful contribution. The goal is for your total daily intake, combining both food and supplements, to reach approximately 220-250 mcg. This collaborative approach ensures you're thoughtfully supporting your body's needs. However, it's also important to be mindful of excessive intake; research indicates that consuming more than 1100 mcg per day can lead to thyroid issues. Kelp supplements, in particular, can have highly variable iodine content and should be approached with caution, as they can sometimes lead to excessive levels. 

Considering the long-term impact on cognitive function, ensuring clear and confident iodine intake is a practical step you can take for your baby's development. The WHO's universal salt iodization program stands as one of the most successful public health interventions, demonstrating the profound positive effects of widespread iodine availability. This historical context reinforces the value of being informed about your personal intake. As with any aspect of your prenatal nutrition, discussing your dietary choices and supplement plan with your care provider is always your best resource for your specific situation. They can offer personalized guidance to help you make informed decisions.