Maternal hypothyroxinaemia during early pregnancy and subsequent child development: a 3‐year follow‐up study

To evaluate the impact of maternal hypothyroxinaemia during early gestation (fT4 below the lowest tenth percentile and TSH within the reference range: 0.15-2.0 mIU/l) on infant development, together with any subsequent changes in fT4 during gestation.

A prospective 3-year follow-up study of pregnant women and their children up to the age of 2 years. MEASUREMENTS: Child development was assessed by means of the Bayley Scales of Infant Development in children of women with hypothyroxinaemia (fT4 below the tenth percentile at 12 weeks' gestation) at 12 weeks' gestation (cases), and in children of women with fT4 between the 50th and 90th percentiles at 12 weeks' gestation, matched for parity and gravidity (controls). Maternal thyroid function (fT4 and TSH) was assessed at 12, 24 and 32 weeks' gestation. The mental and motor function of 63 cases and 62 controls was compared at the age of 1 year, and of 57 cases and 58 controls at the age of 2 years.