Background: Pregnancy causes physiological changes in maternalthyroid function tes ts and changes are sometimes confusedwith thyroid abnormalities therefore the aim of this s tudywas to determine the
TSH levels in the firs t trimes ter in pregnantwomen without a his tory of thyroid disease .And to determinethe importance of screening of thyroid diseases in earlypregnancy.Materials and Methods: This is a descriptive analytic s tudyon ۱۲۰۰ women in the firs t trimes ter of the pregnancy that referredto prenatal clinic for routine prenatal care, for each casea checklis t was completed containing demographic information(age, weight and height), as well as the variables required forresearch (his tory of previous pregnancy, his tory of medical diseasesand family his tory of thyroid disease ). In the quantitativevariables, the mean of the data center and the s tandard deviationwas used to describe the scattering of data. Prevalence and percentagewere used to describe the data in qualitative variables.t tes t and Chi-square tes t were used to analyze the data. Thenormalization of the Kolmogorov-Smirulov tes t was s tudied.The significance level was considered to be ۰.۰۵ All analyzeswere performed using SPSS software version ۲۲.Results: Seventy percent of our cases were aged between ۲۵and ۳۵ years old. The mean age of pregnant women was ۲۹.۴۴± ۰.۱۳ and the mean of
TSH level in the firs t trimes ter of pregnancywas ۲.۴۰ ± ۰.۴۹. There was no significant relations betweendifferent age groups, abortion, number of pregnanciesand diabetes in our cases and
TSH level (P> ۰.۰۵). However,there was a significant correlation between BMI, family historyof thyroid diseases and hypertension in pregnant womenwithout pas t medical his tory of thyroid diseases and
TSH levelin the firs t trimes ter of pregnancy (P <۰.۰۵).Conclusion: The results of this s tudy showed that
TSH levelin majority of our cases ranging from ۲.۵ to ۳.۹ mUl/ml. ۳۱۰(۲۵%) cases more than ۲.۵ mUl/ml and ۱۸۸ (۱۵.۶۶%) casesmore than ۳.۹ mUl/ml. According to this approximately ۱۶%our cases need assessment for hypothyroidism and requiredtreatment. If screening of
TSH in firs t trimes ter was not done۱۸۸ cases of hypothyroidism would not have diagnosed. It isreasonable to perform this tes t in firs t visit of pregnancy routinely.