A Case Control Study To Evaluate The Correlation Of Hypothyroidism In Pregnant Women With Adverse Pregnancy Outcome Compared To Pregnant Women With Normal Pregnancy Outcome

Abstract

Background: Thyroid dysfunction is one of the most common endocrine disorders affecting women of reproductive age group including pregnancy. In pregnancy overt hypothyroidism is seen in 0.2%1 cases and sub-clinical hypothyroidism in 2.3%2 cases. On the whole the reported prevalence of thyroid disorders during pregnancy ranges from 2 to 5% in pregnant women3&4.This is because pregnancy increases the demand on maternal thyroid gland. When mother fails to cope with this she develops hypothyroidism. Untreated or uncontrolled hypothyroidism is associated with Abortions, Pregnancy Induced Hypertension, Placental Abruption, Preterm labour, IUGR, Gestational diabetes, IUD , lead to increased cesarean deliveries, NICU admissions and reduced intellectual function in the offspring.6 Treated hypothyroidism was not associated with any increase in maternal, fetal or neonatal complications and did not affect the mode of delivery.7 Objective: To evaluate the association of hypothyroidism in pregnant women with adverse pregnancy outcome and compare it with pregnant women with normal pregnancy outcome and to compare the association of Hypothyroidism using trimester specific Thyroid Endocrine Society (TES)criteria and trimester specific Indian reference range (IRR)criteria pregnancy specific cut off values for the diagnosis of hypothyroidism. Methodology: Design: one year Case control study. Setting: KLES Dr. Prabhakar Kore Hospital and Medical Research Centre, KLE University’s teaching hospital attached to Jawaharlal Nehru Medical College Belgaum Study Period: One year from January 2012 to December 2012.Sample Size: 200cases and 200 controls Inclusion criteria: Cases: Pregnant women with minimum of any one of the following pregnancy complications in the present pregnancy Abortions, Hyperemesis gravidarum, Preterm delivery , IUGR , Preeclampsia/Gestational hypertension, IUD, Gestational diabetes, Abruptio placenta, And Controls: Pregnant women at similar gestational age with no previous or present pregnancy complication were recruited as controls.(Where ever applicable) Exclusion criteria : Is Pregnant women with previously diagnosed thyroid dysfunction/ autoimmune disorder, family history of thyroid dysfunction, Multiple pregnancy& hyperthyroidism Patient related information was collected and entered in to data collection instrument (Annexure II) after taking Informed written consent from the women from both cases and controls and they were subjected to testing of Sr.TSH, Free T3 and Free T4 levels only once. 2ml of blood samples was collected in a plain vaccutainer and sent to laboratory. At the laboratory FT3, FT4 & TSH levels are assessed and then analyzed by 1. Trimester specific cutoffs recommended by Thyroid Endocrine Society(TES) 2. Trimester specific cutoffs recommended for Indian pregnant women by RK Marwaha and et al that is the Indian reference range(IRR)criteria. Results: In the present study it was observed that the prevalence of hypothyroidism is significantly higher in cases when compared to controls according to trimester specific TES criteria (p=0.001) and IRR criteria (p=0.0001) values as cutoffs and the Odd’s ratio of 11.27 and 95% confidence interval between cases and controls ( 6.3 & 20.15). When individual complications of pregnancy and association with hypothyroidism were considered it was observed that 48.5%(TES) of Preeclampsia cases were found to be hypothyroid and with the highest odds ratio of 10.7(95% confidence interval between 5.58-20.7) Increased association was observed for Abruption(OD-8.6 95% CI-3.48-21.34), spontaneous abortions(OD-7.5 95%CI-3.28-17.5), Intra uterine growth retardation(OD-7.4 95%CI-3.72-15.05) gestational diabetes mellitus(OD-6.9 95%CI-2.86-16.6), and Intra uterine death(OD-6.0 95%CI-2.3-15.8) and the least association was observed with spontaneous preterm births (OD-1.9 95%CI-0.5-7.2) Conclusion: More number of hypothyroid women can be detected by using the trimester specific thyroid endocrine society cutoff values than to trimester specific Indian reference range cutoff values for pregnancy as the cutoff value of S.TSH is lower for TES criteria. So for a clinical set up it is recommended to follow TES criteria for the screening of hypothyroidism in pregnancy. Hence Until the controversy regarding Universal screening versus screening for targeted high risk pregnant women settles, it is advisable to offer screening for women with present adverse pregnancy outcome. It is worthwhile screening these women as hypothyroidism can be detected especially Subclinical hypothyroidism early and treated by LT4 replacement would probably reduce adverse pregnancy outcomes associated with hypothyroidism.