Pathological gestational weight gain (GWG) is a risk factor for obstetric and perinatal complications. High metabolic activity of adipose tissue and the placenta during pregnancy manifests as an increased production of adipokines that are involved in glucose regulation and insulin sensitivity. The aim of this study was to determine the role of resistin in the genesis of metabolic disorders in pathological GWG pregnancies. The 163 pregnant women were examined in the study: 97 (59.5%) had normal, 18 (11.0%) had insufficient and 48 (29.4%) had excessive prepregnancy weight and obesity. GWG was the recommended level in 56 (34.4%), insufficient in 33 (20.2%), and excessive in 74 (45.4%) women. Anthropometry was performed in each trimester of pregnancy, the weight gain was measured, and the percentage of body fat mass, concentrations of resistin, glucose, insulin, and the HOMA-IR were evaluated. Positive associations were found between hyperresistinemia in the second trimester of pregnancy, and subsequent weight gain (r = 0.27, P = 0.0006), percentage of body fat mass (r = 0.93, P = 0.000) and insulin resistance (r = 0.89, P = 0.000) in late pregnancy; these associations were especially evident in excessive GWG. Determination of predictors of insulin resistance, associated with endocrine activity of adipose tissue, such as the adipokine resistin, in the second trimester of pregnancy may help to predict the severity of metabolic shifts during pregnancy and the risk of developing obstetric and perinatal complications.