Maternal serum TSH value in early pregnancy and its relation with pregnancy outcome

Abstract

The present prospective clinical study was carried out in 200 pregnant women with single intrauterine pregnancy of gestational age between 6-14th weeks. Thyroid function tests namely TSH, FT3, FT4, TPO Ab and TG Ab were done. The patients were followed till delivery for perinatal outcome. Maternal and cord blood for TSH were collected at the time of delivery. The role of levothyroxine on maternal and fetal outcome in these patients was also studied. Mean FTg and FT4 levels in Group 1 were comparable. Mean TSH levels at first trimester in Group 2 were significantly higher than those in Group 1 (p — 0.04). The patients with raised TSH levels were given treatment with levothyroxine as per their TSH levels. The mean TSH levels at the time of delivery in Group 2 patients were significantly lower as compared to the mean TSH levels in the first trimester and they were comparable to euthyroid patients (p = 0.32). The TPOAb positivity was found to be 14%. The TGAb positivity was found to be 7%. It was observed that all patients in Group 1 were thyroid auto-antibody negative. Cord blood TSH values were 4.47±2.1 mlU L-1 and 6.88±2.3 mlU L-1 in Group 1 and Group 2, respectively, p<0.01. The correlation between maternal TSH at first trimester and cord blood TSH was positive (r = +0.227, p<0.01). Negative correlation was observed between the TSH values in first trimester and average birth weight of neonates (r = -0.038, p<0.05). Negative correlation was observed between cord blood TSH and birth weight of babies (r = -0.15, p<0.05). Subclinical hypothyroidism and thyroid antibody positivity were associated with increased incidence of low birth weight babies. However, biochemical parameters and perinatal outcomes were better after thyroxine replacement therapy. It can be inferred that optimum thyroxine replacement in early gestation results in good perinatal outcome.