BackgroundPatients with ≥ 3 recurrent spontaneous miscarriages are classified as having RSM. Polycystic ovary syndrome (PCOS) is associated with insulin resistance (IR). The purpose of this study is to evaluate the association of IR and RMS.MethodsPresent case- control prospective study was performed on 100 women in control group (with a history of at a live birth and no history of one more abortion) and study group (with a history of ≥ 3 RMS) who were not diabetes and PCOS. Two groups matched in base of age and body mass index. Blood was withdrawn from the case and control patients for the determination of the fasting blood glucose (FG), fasting insulin (FI) levels and ultrasonography was performed on all the patients.ResultsThe observed differences between age, FG and FG to FI ratio levels in case and control groups were not significant (p > 0.05) but it was significant about fasting insulin (p = 0.0119). FI of < 20 μu/ml or ≥ 20 μu/ml in case and control group was significant (Chi-square: 4.083, p: 0.0433, odds ratio: 4.4386, CI95% = 1.1541 to 17.0701), whereas the difference between absolute and proportional frequency of patients with FG to FI ratio of < 4.5 and ≥ 4.5 in case and control groups was not significant (Chi-square: 2.374, p = 0.123).ConclusionCurrent study showed that in women with RPL, in Iranian race like Americans, frequency of insulin resistance in high, therefore there is a probability of the degree of insulin resistance in women with RPL.