The aim of the present study was to evaluate serum adiponectin, leptin, apelin and omentin levels to explore metabolic changes occurring during fasting in the month of Ramadan. The study was designed as a prospective study. The patients were divided into two groups, each comprising 20 patients: Group I, fasting pregnant women, and Group II, non-fasting pregnant women. The patients' age, parity, gestational week and body mass index were recorded. Adiponectin and omentin levels were significantly lower in fasting pregnant women (p<0.001). When the two groups were compared in terms of serum leptin and apelin levels, both were found to be significantly higher in Group I than in Group II. The findings of the present study suggest that pregnant women who are willing to fast during 24-38 weeks' gestation should be informed about insulin resistance.