Introduction: Thyroid function testing in pregnancy is an area of concern for pregnant women, doctors and laboratories. Some women are known to have thyroid disease before pregnancy and require monitoring to ensure no harm comes to them or their baby. Thyroid disorders can have adverse reproductive and pregnancy implications. Thus, the aim of this study was to assess blood level of thyroid function test during early gestation and assess associated factors among pregnant women attending antenatal care clinic in Nekemte Referral Hospital.Methods: Facility-based Cross-sectional study design was deployed to collect information from 300 Pregnant women (<20 gestation weeks) attending antenatal clinic from March to May, 2017. Interviewer-administered structured questionnaire was used to obtain information and blood samples were collected from pregnant women for estimation of thyroid function test after getting written consent. Data was entered to Epi info version 3.5.3, cleaned and analyzed using SPSS version 24 and Multivariable analysis were used to examine the association between dependent and independent variables. Odds ratios (ORs) and their 95% confidence intervals (CIs) were calculated. Significance was declared at P-value 0.05.Result: A total of 300 pregnant women were interviewed and blood sample collected from them for thyroid function test with a response rate of 90.1%. Among the study subjects 14(4.7%) have Subclinical Hypothyroidism (SCH). Husband occupation, presence of Radio in the household, presence of television in their house and treating drinking water at household level were among factors associated with development of Hypothyroidism.Conclusion and Recommendation: In this study, Subclinical Hypothyroidism (SCH) among pregnant women in early gestation is significant 14(4.7%) above the expected 2.5% of American thyroid association cut point. Husband occupation, Presence of media for information and treatment of drinking water were the associated factors. So, health workers should always update pregnant women on importance of consuming proper utilization of iodized salt. Health workers shall also teach pregnant women on personal and environmental hygiene.