Hypothyroidism during pregnancy

I have a 27-year-old patient diagnosed with hypothyroidism in the 8th week of pregnancy. She received conflicting opinions regarding risk for her baby and wants to get more information. I also found conflicting information in the literature. How should I advise her?

Pregnant patients with untreated hypothyroidism are at increased risk of obstetric complications. Adequate treatment with thyroid hormones greatly reduces the frequency of these complications. Observational studies suggest that children whose mothers had hypothyroxinemia in early pregnancy have lower IQs than matched controls. Another study has shown that even if levothyroxine therapy is started after the first trimester, there is an excellent chance children will have normal neuropsychologic development.