Does a newborn require testing after delivery if the mother has hypothyroidism (underactive thyroid) during pregnancy?

From the Guidelines

Babies born to mothers with hypothyroidism during pregnancy should be tested after delivery, but the provided evidence does not specifically support this recommendation for hypothyroidism, it only mentions the need for awareness of neonatal thyroid dysfunction in cases of maternal Graves' disease. The evidence from the American College of Obstetricians and Gynecologists (ACOG) Practice Bulletin on Thyroid Disease in Pregnancy 1 focuses on the management of thyroid disease in pregnancy, including the treatment of hypothyroidism with levothyroxine, but does not provide clear guidance on the necessity of testing the baby after delivery for mothers with hypothyroidism. However, considering the potential risks of maternal hypothyroidism on fetal development, it is reasonable to consider testing the baby's thyroid function after delivery as a precautionary measure. Some key points to consider in the management of maternal hypothyroidism include:

• Treatment with levothyroxine to maintain a normal TSH level
• Adjusting the dosage every four weeks until the TSH level is stable
• Checking the TSH level every trimester It is essential to note that the provided evidence does not specifically address the question of testing babies after delivery for mothers with hypothyroidism, but rather focuses on the management of thyroid disease during pregnancy. In real-life clinical practice, it is crucial to prioritize the health and well-being of both the mother and the baby, and considering the potential risks associated with maternal hypothyroidism, testing the baby's thyroid function after delivery may be a reasonable precaution. Some possible testing approaches may include:
• Checking the baby's thyroid function within the first 48-72 hours of life
• Measuring thyroid stimulating hormone (TSH) and free T4 levels through a heel-stick blood test
• Evaluating the baby promptly if abnormalities are detected, and considering treatment with liquid levothyroxine if necessary.

From the Research

Hypothyroidism in Pregnancy and Newborn Testing

• Hypothyroidism is a common pregnancy-related thyroid disorder, affecting 2-5% of pregnant women 2, 3.
• The condition can be overt or subclinical, with overt hypothyroidism diagnosed by a decreased FT4 and subclinical disease characterized by a normal FT4 3.
• Poorly controlled hypothyroidism is associated with pregnancy complications and developmental delays in the offspring 3.
• Treatment consists of replacement with levothyroxine and regular monitoring, with most pregnant women requiring an increase in their dosing from 25% to 30% 3, 4.

Testing for Newborns

• There is no direct evidence in the provided studies that suggests newborns of mothers with hypothyroidism require testing after delivery.
• However, it is essential to monitor and manage maternal thyroid disease during pregnancy to ensure favorable pregnancy outcomes 5.
• Evaluating and treating women with thyroid disease during pregnancy requires careful observation and management to prevent adverse effects on the fetus 5.

Management and Treatment

• Levothyroxine replacement therapy is the standard treatment for hypothyroidism, started at 1.5 to 1.8 mcg per kg per day 4.
• Women with hypothyroidism who become pregnant should increase their weekly dosage by 30% up to nine doses per week, followed by monthly evaluation and management 4.
• Regular assessment of TSH levels and symptom relief is crucial for managing hypothyroidism 6.