Maternal thyroid function, iodine deficiency and fetal development.

In an area of New Guinea where there is dietary iodine deficiency, measurements of thyroid function have been made on women of child-bearing age, several of whom were pregnant at the time. The outcome of these pregnancies, and also of those occurring in the four preceding years, were examined in relation to indices of thyroid function. More stillbirths, infant deaths and endemic cretins occurred among the offspring of women who showed biochemical evidence of iodine deficiency, without clinical evidence of hypothyroidism. This situation differs from that of untreated myxoedema or congenital hypothyroidism in women, which is usually associated with altered menstrual function, infertility or repeated abortion. Mechanisms that may account for these differences and the possible implications are discussed.