Objective: To test if TSH level above 2.1 mlU/L is associated with first trimester pregnancy loss in anti-TPO antibody negative women in Bangladesh. An unmatched case-control study was conducted in Bangladesh. Patients were recruited following predefined inclusion and exclusion criteria. Clinical measures were taken as well as data on socioeconomic and physical characteristics were collected. Patients were grouped according to their TSH level—Group I with TSH ≤2.1 mlU/L and Group II with TSH > 2.1 mlU/L. We found relatively higher number of women in the case group (18) whose TSH level was above 2.1 mlU/L compared to 7 women in control group. In Group I 45.74% had lost pregnancy while 54.26% had continuing pregnancy during the first trimester. Among the Group II patients, 78% had miscarriage and 28% did not have miscarriage. The association between TSH level and first trimester pregnancy loss was statistically significant (p=.0196).In multivariate analysis, odds ratio for TSH level (OR 4.0, 95% CI: 1.44-11.16) indicates that odds of having miscarriage whose TSH level is above 2.1 mlU/L is 4 times compared to those with TSH level below 2.1 mlU/L after adjusting for the effects of age and BMI. At a global level, the findings of this study provide evidence to the existing discussion on redefining the upper limit of TSH level that is related to first trimester pregnancy loss. At the local level, the results will have direct implication in facilitating management of future pregnancies particularly during the first trimester among Bangladeshi thyroid autoantibody negative women.