Serum thyroxine and thyroid stimulating hormone levels in maternal circulation and cord blood at the time of delivery

ABSTRACT

The aim of this study was to know whether the alterations of maternal thyroid function were also present in the newborn at birth. Retrospective study of thyroid related hormones in pregnant mothers at time of delivery and their cord blood samples. Department of Obstetrics and Gynecology, Government Mian Munshi Hospital and Centre for Nuclear Medicine [CENUM], Mayo Hospital, Lahore. 175 women delivered during the year 2001. maternal and cord serum T[4] and TSH. The mean age of women was 27.5 +/- 4.7 years and average weight of their babies was 3.3 +/- 0.6 kg. The median T[4] and TSH concentrations of mothers, particularly T[4], at delivery were significantly higher than controls [p<0.001 and p<0.01 respectively]. T[4] levels were negatively correlated to TSH levels in both mothers and neonates with low degrees of correlation. The median T[4] was significantly lower and median TSH was significantly higher in neonates as compared to mothers [p<0.001]. A relatively higher degree of correlation was observed among T[4] levels of mothers and neonates. The neonates of mothers having TSH levels below 0.35% mIU/L exhibited a heterogeneous patter of T[4] and TSH levels, which were not consistent with their mothers. In mothers who had TSH level within normal euthyroid range [0.36-4.0 mIU/L] neonates had T[4] levels within normal euthyroid range but 13.7% of them had TSH levels above 10 mIU/L. Overall 13.1% neonates had TSH level above 10mIU/L which indicated mild degree of iodine deficiency in Lahore. Neonates of about 13% pregnant women are at risk of iodine deficiency. Iodine supplementation in women of reproductive age is required before pregnancy as mild iodine deficiency is prevalent in Lahore