Impact of Undiagnosed Hypothyroidism During Pregnancy on Baby's Development

What is the impact on the baby if hypothyroidism is discovered at 7 months of pregnancy?

Hello doctor, I have been diagnosed with hyperthyroidism for about 5 to 6 years and have been continuously receiving treatment and medication, but I haven't had blood tests every month.
It was only at 28 weeks of pregnancy that I discovered my thyroid levels had dropped low since November.
I immediately stopped taking the hyperthyroid medication.
I have been taking iodine-containing vitamins since the third month of my pregnancy, and I am unsure if this has any remedial effect on the fetus.
I am very concerned about the potential impact on my baby's neurological and cognitive development, which could lead to intellectual disabilities.
Is there a way to assess the effects on the fetus now, or what can be done to remedy the situation? After the baby is born, how should I address any potential impacts?

Worried Mom, 30~39 year old female. Ask Date: 2017/02/17

Dr. Lin Yishou reply Pediatrics

Dear Parents, during pregnancy, hypothyroidism can indeed affect the fetal cognitive development.
The only remedy is to treat hypothyroidism during the pregnancy.
As for cretinism, it refers to the condition where the child continues to have low thyroid function after birth.
Therefore, if the child's thyroid function is closely monitored after birth, it is unlikely that cretinism will occur.
Thus, what the mother needs to do now is to promptly treat hypothyroidism during the pregnancy.
After birth, please have the physician monitor the child's thyroid function.
This way, the potential impact on the child can be minimized.

Reply Date: 2017/02/17

More Info

Undiagnosed hypothyroidism during pregnancy can have significant implications for both the mother and the developing baby. Thyroid hormones are crucial for fetal brain development, particularly during the first trimester when the fetal thyroid is not yet fully functional. Insufficient levels of these hormones can lead to a range of developmental issues, including cognitive impairments and, in severe cases, congenital hypothyroidism, which can result in intellectual disabilities.

In your case, it appears that you have a history of hyperthyroidism, and it was only at 28 weeks of pregnancy that you discovered you had developed hypothyroidism. The fact that you were taking medications for hyperthyroidism and then stopped them upon discovering the hypothyroid condition is important. However, the timing of your diagnosis is critical, as the first trimester is when the fetus is most vulnerable to the effects of maternal thyroid hormone levels.

1. Understanding Your Thyroid Levels: The thyroid-stimulating hormone (TSH) levels are particularly important. Elevated TSH levels indicate that your body is not producing enough thyroid hormones (T3 and T4). If your TSH was significantly high, it suggests that your hypothyroidism could have been present for some time, potentially affecting the fetus during critical periods of development.
2. Impact on the Baby: If hypothyroidism is not managed properly during pregnancy, it can lead to developmental delays, lower IQ, and other neurodevelopmental disorders in the child. The risk of these outcomes is particularly pronounced if the hypothyroidism is severe and untreated during the first trimester. However, the extent of the impact can vary based on the severity and duration of the hypothyroid state.

3. Potential Remedies and Monitoring: Since you have started taking iodine-containing vitamins, it is essential to ensure that you are receiving adequate thyroid hormone replacement therapy. Iodine is crucial for thyroid hormone production, but it is not a substitute for thyroid hormones themselves. You should consult with an endocrinologist or a maternal-fetal medicine specialist to determine the appropriate dosage of levothyroxine (if prescribed) to normalize your thyroid hormone levels. Regular monitoring of TSH, T3, and T4 levels will be necessary to ensure that you are within the target range.

4. Postnatal Considerations: After the baby is born, it is crucial to monitor the child for any signs of developmental delays or thyroid issues. Newborn screening programs in many countries include tests for congenital hypothyroidism, which can help identify any issues early on. If the baby is diagnosed with hypothyroidism, prompt treatment with thyroid hormone replacement can lead to normal development.

5. Future Monitoring and Support: It is also advisable to have ongoing follow-up with healthcare providers to monitor both your thyroid function and your child's development. Early intervention services can be beneficial if any developmental delays are identified.

In summary, while undiagnosed hypothyroidism can pose risks to fetal development, timely intervention and management can mitigate these risks. It is crucial to work closely with your healthcare team to ensure both your health and the health of your baby are prioritized. Regular check-ups and appropriate treatment can lead to positive outcomes for both you and your child.

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