Severe Maternal Hypothyroidism Corrected Prior to the Third Trimester Is Associated with Normal Cognitive Outcome in the Offspring
Thyroid, 06/11/2012
Downing S et al. – Although the findings do not exclude a subtle impact of maternal hypothyroidism (MH) during early gestation on intellectual function, the normal cognitive outcome despite overt MH should provide data with which to counsel mothers who have overt hypothyroidism early in pregnancy. Aggressive thyroid hormone replacement as soon as possible is important, but early termination of the pregnancy because of fear that the baby will have significant cognitive delay is not warranted.
Methods- The authors identified three women who had TSH receptor blocking Ab–induced MH during pregnancy and were treated with L-thyroxine (L-T4), starting at 27 weeks, 5 weeks, and the first month of gestation.
- The corresponding pretreatment serum TSH levels in the two women in whom data were available were 68 and 65mU/L, falling to 6mU/L at 25 and 24 weeks of gestation, respectively.
- The third woman with MH required 0.5mg of L-T4 to normalize her thyroid hormone levels by 4 months of gestation.
- Their infants were also treated with L-T4 after neonatal screening that identified congenital hypothyroidism (CH).
- Neuropsychological tests to assess intelligence, language, memory, and visual-motor performance were administered to these three infants at 5.4 years of age (range 5.1–6.1) and to three sibling controls at 6.8 years (range 9.1–3.0).
- Children born after MH had average or above average results on all parameters. Comparative scores of the neuropsychological tests in sibling pairs for full-scale intelligence quotient (IQ) and performance IQ were variable; some scores were higher and some were lower in CH children.
