Frequency of subclinical hypothyroidism and mean serum TSH level in first trimester of pregnancy.

Objective: To find out the frequency of subclinical hypothyroidism (SCH) in our pregnant population during 1st Trimester and the mean TSH level in first trimester of pregnancy. Study Design: Cross Sectional Descriptive study. Setting: Dow University Hospital and Dr Ruth KM Pfau CHK. Period: June 2015 to May 2016. Material & Methods: All Pregnant women with <14 weeks gestation were screened for Serum TSH level. Data were recorded after informed consent and institutional ethical approval. Variables recorded were age, parity, gestational age and serum TSH level. Data were analyzed on SPSS version 16. Mean and SD were calculated for quantitative variables ie. Age, parity, gestational age, serum TSH level and serum free T4 level. Mean TSH level according to age group, parity and gestational age groups were determined by applying ANOVA test. Correlation of Serum TSH level with the maternal age, parity and gestational age groups were also assessed by Pearson Correlation test. Significant P-value was taken as <0.05. Results: The frequency of SCH found was 19.35% by taking cut off limit of <2.5 IU/L and 3.55% by taking cut off limit of <4.5 IU/L among total of 310 pregnant women. Mean TSH level was 1.84±1.36 IU/L. The mean maternal age was 27.22 ± 4.43 yrs. while median parity was 1. Mean gestational age of these patients were 9.41 ± 2.748 weeks and out of these 160 (51.61%) were between 4-9 weeks and 150(48.38%) between 10-14 weeks. Majority (74%) of these women belonged to lower middle socioeconomic class. Mean TSH level coorelation between different age groups, parity groups and gestational age groups were found to be insignificant. Conclusion: The prevalence of SCH is not so high and mean TSH level in our population was 1.84 IU/L. But to establish reference range for Pakistani population, further studies in population of different backgrounds and geographical distribution needs to be evaluated.