SUBCLINICAL HYPOTHYROIDISM IN PREGNANCY; IS THERE A NEED FOR PHARMACOLOGICAL INTERVENTION?
Keywords:Thyroid hormones, Subclinical hypothyroidism, Pregnancy complications, Levothyroxine
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.
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