SUBCLINICAL HYPOTHYROIDISM IN PREGNANCY; IS THERE A NEED FOR PHARMACOLOGICAL INTERVENTION?

Shripad Hebbar,Sneha Doizode,Sahan Kumar,Sapna Amin

doi:10.22159/ijpps.2017v9i3.16542

Abstract

Objective: To find the prevalence of subclinical hypothyroidism in the first trimester of pregnancy and to compare the maternal and perinatal outcome in them with euthyroid mothers.Methods: The present study was a prospective observational case-control study done in a tertiary hospital over the period of one and half years. Pregnant women in the first trimester of pregnancy were tested for Thyroid Stimulating Hormone (TSH) levels and those who had TSH>2.5mIU/l, free T3 and free T4 estimation was carried out on the same sample. A total of 171 women could be followed up till delivery and their first-trimester thyroid profile was available for analysis. They were grouped into two groups, Group 1: all women with TSH level>2.5 mIU/l, considered to be hypothyroid (n=79), Group 2: women with euthyroid status with TSH levels 0.1 to 2.5 mIU/l (n=95). All the neonates delivered in the first group had cord blood TSH estimation.Results: In the study period, there were 2632 deliveries. The number of pregnant women with first trimester TSH levels>2.5 mIU/l were 79, giving the prevalence rate of 3 % for subclinical hypothyroidism during pregnancy. The obstetric complications observed were gestational hypertension 3.8%, gestational diabetes 6.3%, placenta praevia1.3% and preterm delivery 7.6%. The perinatal complications included Intrauterine growth restriction (IUGR) 1.3%, Low Birth Weight (LBW) 3.8%, perinatal asphyxia 2.5% and neonatal hypothyroidism 1.3%. Only preterm delivery appeared to be significantly associated with subclinical hypothyroidism.Conclusion: The observed complication rates were much similar, in fact, lesser with gestational diabetes, pregnancy hypertension, IUGR, LBW compared to global and Indian prevalence rates. This indicates that the cut-off for diagnosing subclinical hypothyroidism should be derived from TSH assays from the local geographic population and should guide the treating physician to establish appropriate TSH ranges where definite therapeutic intervention is required to improve the maternal and foetal outcome.

Highlights

After diabetes, hypertension and anaemia, thyroid dysfunction constitutes for the majority of medical disorders in pregnancy
There is increased requirement for thyroid hormone during pregnancy and in the first trimester of pregnancy, fetus depends upon placentally transferred maternal thyroxin for its neuronal development, deficiency of which can result in mental retardation and cretinism [2]
The duration of pregnancy was calculated from the date of last menstrual period (LMP) and cross verified with their first-trimester CRL values

Summary

Introduction

Hypertension and anaemia, thyroid dysfunction constitutes for the majority of medical disorders in pregnancy. Hypothyroidism (2.5%) is more prevalent than hyperthyroidism (1 to 0.4%) [1]. There is a significant change in thyroid hormone metabolism in pregnancy. In a woman with poor thyroid reserve, thyroid deficient state occurs due to increased urinary loss of thyroxine due to increase in glomerular filtration rate (GFR) and placental transfer of thyroxin to the growing fetus. There is increased requirement for thyroid hormone during pregnancy (one and half times) and in the first trimester of pregnancy, fetus depends upon placentally transferred maternal thyroxin for its neuronal development, deficiency of which can result in mental retardation and cretinism [2]. Congenital hypothyroidism is known to occur more often in women with hypothyroidism in pregnancy and has a greater impact in the cognitive and scholastic performance of the child in future [5, 6]

Methods

Results

Conclusion